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WO2024262492A1 - Élément de batterie solaire et procédé de fabrication d'élément de batterie solaire - Google Patents

Élément de batterie solaire et procédé de fabrication d'élément de batterie solaire Download PDF

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Publication number
WO2024262492A1
WO2024262492A1 PCT/JP2024/022041 JP2024022041W WO2024262492A1 WO 2024262492 A1 WO2024262492 A1 WO 2024262492A1 JP 2024022041 W JP2024022041 W JP 2024022041W WO 2024262492 A1 WO2024262492 A1 WO 2024262492A1
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Prior art keywords
oxide film
layer
region
polysilicon layer
type
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Japanese (ja)
Inventor
福久 立花
勝彦 白澤
健次 福地
祐太 入江
宏明 ▲高▼橋
鉄平 山下
友樹 湯浅
憲和 伊藤
浩一郎 新楽
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Kyocera Corp
National Institute of Advanced Industrial Science and Technology AIST
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Kyocera Corp
National Institute of Advanced Industrial Science and Technology AIST
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  • This disclosure relates to solar cell elements and methods for manufacturing solar cell elements.
  • a solar cell element that has a structure called POLO (polysilicon on oxide) (also called the POLO structure), in which an extremely thin oxide film and a layer of polycrystalline silicon doped with impurity elements are stacked in a region on the surface of a crystalline silicon substrate (also simply called the substrate) or in a region located inside the substrate and extending from a portion along the surface of the substrate to the surface of the substrate (see, for example, the description in Non-Patent Document 1).
  • POLO polysilicon on oxide
  • a solar cell element and a method for manufacturing the solar cell element are disclosed.
  • the solar cell element includes a substrate, an oxide film, and a polysilicon layer.
  • the substrate has a first region that is a region of a semiconductor of a first conductivity type.
  • the oxide film is in contact with the first region.
  • the polysilicon layer is in contact with the surface of the oxide film opposite to the first region.
  • the polysilicon layer contains a dopant.
  • the polysilicon layer includes a second region. The second region is a region of the polysilicon layer on the oxide film side that is in contact with the oxide film. In a region from the second region through the oxide film to the first region, the distribution of the concentration of the dopant in a direction from the surface of the polysilicon layer opposite to the substrate toward the substrate has a maximum first peak and a second peak.
  • the second peak is present at a position 3 nm or more away from the position showing the first peak in a direction from the first region through the oxide film toward the second region.
  • the dopant is a dopant of the first conductivity type or a second conductivity type different from the first conductivity type.
  • the solar cell element includes a substrate and a polysilicon layer.
  • the substrate has a first region that is a region of a semiconductor of a first conductivity type.
  • the substrate includes an oxide film.
  • the oxide film is located between the first region and the polysilicon layer, and is in contact with both the first region and the polysilicon layer.
  • the polysilicon layer is in contact with the substrate.
  • the polysilicon layer contains a dopant.
  • the polysilicon layer includes a second region. The second region is a region of the polysilicon layer on the oxide film side that is in contact with the oxide film.
  • the distribution of the dopant concentration in the direction from the surface of the polysilicon layer opposite the substrate toward the substrate has a maximum first peak and a second peak.
  • the second peak is located at a position 3 nm or more away from the position showing the first peak in the direction from the first region through the oxide film toward the second region.
  • the dopant is a dopant of the first conductivity type or a dopant of a second conductivity type different from the first conductivity type.
  • One aspect of the method for manufacturing a solar cell element includes a first step, a second step, a third step, and a fourth step.
  • first step an oxide film is formed on the inside of a crystalline silicon substrate including a first region, which is a region of a semiconductor of a first conductivity type, and on a portion along the surface of the substrate or on the surface of the substrate, the oxide film being in contact with the first region.
  • second step a first layer of intrinsic crystalline silicon is formed on the oxide film.
  • a second layer of amorphous silicon having a thickness greater than that of the first layer and containing a dopant is formed on the first layer.
  • a heat treatment is performed to diffuse the dopant contained in the second layer toward the first layer and the oxide film while promoting crystallization of the amorphous silicon of the second layer, and a polysilicon layer is generated from the first layer and the second layer that is located on the oxide film and contains the dopant.
  • the dopant is a dopant of the first conductivity type or a second conductivity type different from the first conductivity type.
  • the solar cell element includes a substrate, an oxide film, and a polysilicon layer.
  • the substrate has a first region that is a region of a semiconductor of a first conductivity type.
  • the oxide film is in contact with the first region.
  • the polysilicon layer is in contact with the surface of the oxide film opposite to the first region.
  • the polysilicon layer contains a dopant.
  • the polysilicon layer is a layer generated from a first layer of intrinsic crystalline silicon located on the oxide film and a second layer of amorphous silicon located on the first layer, having a thickness greater than that of the first layer, and containing the dopant, by performing a heat treatment on the first layer and the second layer.
  • the heat treatment is a process that progresses crystallization of the amorphous silicon of the second layer while diffusing the dopant contained in the second layer toward the first layer and the oxide film.
  • the dopant is a dopant of the first conductivity type or a second conductivity type different from the first conductivity type.
  • the solar cell element includes a substrate and a polysilicon layer.
  • the substrate has a first region that is a region of a semiconductor of a first conductivity type.
  • the substrate includes an oxide film.
  • the oxide film is located between the first region and the polysilicon layer, and is in contact with both the first region and the polysilicon layer.
  • the polysilicon layer is in contact with the substrate.
  • the polysilicon layer contains a dopant.
  • the polysilicon layer is a layer generated from a first layer of intrinsic crystalline silicon located on the oxide film and a second layer of amorphous silicon located on the first layer, having a thickness greater than that of the first layer, and containing the dopant, by performing a heat treatment on the first layer and the second layer.
  • the heat treatment is a process that progresses crystallization of the amorphous silicon of the second layer while diffusing the dopant contained in the second layer toward the first layer and the oxide film.
  • the dopant is a dopant of the first conductivity type or a second conductivity type different from the first conductivity type.
  • FIG. 1 is a cross-sectional view that illustrates an example of the configuration of a solar cell element according to a first embodiment.
  • FIG. 2 is an enlarged cross-sectional view that illustrates a schematic view of part II in FIG. 1 in the configuration of the solar cell element according to the first embodiment.
  • FIG. 3 is a flow chart showing an example of a method for manufacturing a solar cell element according to the first embodiment.
  • FIG. 4 is a cross-sectional view that illustrates an example of a configuration during the course of manufacturing the solar cell element according to the first embodiment.
  • FIG. 5 is a cross-sectional view that illustrates an example of a configuration during the course of manufacturing the solar cell element according to the first embodiment.
  • FIG. 6 is a cross-sectional view that illustrates an example of a configuration during the course of manufacturing the solar cell element according to the first embodiment.
  • FIG. 7 is a cross-sectional view that illustrates an example of a configuration during the course of manufacturing the solar cell element according to the first embodiment.
  • FIG. 8 is a cross-sectional view that illustrates an example of a configuration during the course of manufacturing the solar cell element according to the first embodiment.
  • FIG. 9 is a cross-sectional view that illustrates an example of a configuration during the course of manufacturing the solar cell element according to the first embodiment.
  • FIG. 10 is a cross-sectional view that illustrates an example of a configuration during the course of manufacturing the solar cell element according to the first embodiment.
  • FIG. 11 is a cross-sectional view that illustrates an example of a configuration during the course of manufacturing the solar cell element according to the first embodiment.
  • FIG. 12 is a cross-sectional view that illustrates an example of a configuration during the course of manufacturing the solar cell element according to the first embodiment.
  • FIG. 13 is a cross-sectional view that illustrates an example of a configuration during the manufacture of the solar cell element according to the first embodiment.
  • FIG. 14 is a flow chart showing a method for fabricating samples of various specific examples of the TOPCon structure.
  • FIG. 15 is a flow chart showing a method for fabricating samples of various reference examples relating to the TOPCon structure.
  • FIG. 16 is a diagram showing an example of an image capturing the surface of the n-type polysilicon layer in the sample of Reference Example 6.
  • FIG. 17 is a diagram showing an example of an image capturing the surface of the n-type polysilicon layer in the sample of Example 6.
  • FIG. 18 is a diagram showing an example of an image capturing the surface of the n-type polysilicon layer in the sample of Reference Example 13.
  • FIG. 19 is a diagram showing an example of an image capturing the surface of the n-type polysilicon layer in the sample of Example 13.
  • FIG. 20 is a graph showing an example of the measurement results of the distribution of phosphorus concentration in a part in the first direction obtained by using secondary ion mass spectrometry for each of the samples of Specific Example 4 and Reference Example 4.
  • FIG. 20 is a graph showing an example of the measurement results of the distribution of phosphorus concentration in a part in the first direction obtained by using secondary ion mass spectrometry for each of the samples of Specific Example 4 and Reference Example 4.
  • FIG. 21 is a graph for explaining the characteristics of the distribution of the phosphorus concentration in a part in the first direction obtained by applying secondary ion mass spectrometry to the sample of Specific Example 4.
  • FIG. 22 is a graph for explaining the characteristics of the distribution of the phosphorus concentration in a part in the first direction obtained by applying secondary ion mass spectrometry to the sample of Specific Example 4.
  • FIG. 23 is a graph for explaining characteristics of the distribution of phosphorus concentration in a part in the first direction obtained by using secondary ion mass spectrometry for the sample of Reference Example 4.
  • FIG. 24 is a graph showing an example of the measurement results of the distribution of phosphorus concentration in a part in the first direction obtained by using secondary ion mass spectrometry for each of the samples of Specific Example 6 and Reference Example 6.
  • FIG. 25 is a graph for explaining the characteristics of the distribution of the phosphorus concentration in a part in the first direction obtained by applying secondary ion mass spectrometry to the sample of Specific Example 6.
  • FIG. 26 is a graph for explaining the characteristics of the distribution of the phosphorus concentration in a part in the first direction obtained by applying secondary ion mass spectrometry to the sample of Specific Example 6.
  • FIG. 27 is a graph for explaining characteristics of the distribution of phosphorus concentration in a part in the first direction obtained by using secondary ion mass spectrometry for the sample of Reference Example 6.
  • FIG. 28 is a graph showing an example of the measurement results of the distribution of phosphorus concentration in a part in the first direction obtained by using secondary ion mass spectrometry for each of the samples of Specific Example 2 and Reference Example 2.
  • FIG. 29 is a graph for explaining the characteristics of the distribution of the phosphorus concentration in a part in the first direction obtained by applying secondary ion mass spectrometry to the sample of Specific Example 2.
  • FIG. 30 is a graph for explaining the characteristics of the distribution of the phosphorus concentration in a part in the first direction obtained by applying secondary ion mass spectrometry to the sample of Specific Example 2.
  • FIG. 31 is a graph for explaining characteristics of the distribution of phosphorus concentration in a part in the first direction obtained by using secondary ion mass spectrometry for the sample of Reference Example 2.
  • FIG. 32 is a graph showing an example of a measurement result of the distribution of the concentration of phosphorus in a part in the first direction obtained by using secondary ion mass spectrometry for the sample of Specific Example 3.
  • FIG. 33 is a graph for explaining the characteristics of the distribution of the phosphorus concentration in a part in the first direction obtained by applying secondary ion mass spectrometry to the sample of Specific Example 3.
  • FIG. 34 is a graph showing an example of a measurement result of the distribution of the concentration of phosphorus in a part in the first direction obtained by using secondary ion mass spectrometry for the sample of specific example 5.
  • FIG. 32 is a graph showing an example of a measurement result of the distribution of the concentration of phosphorus in a part in the first direction obtained by using secondary ion mass spectrometry for the sample of Specific Example 3.
  • FIG. 35 is a graph for explaining the characteristics of the distribution of the phosphorus concentration in a part in the first direction obtained by applying secondary ion mass spectrometry to the sample of Specific Example 5.
  • FIG. 36 is a cross-sectional view that illustrates an example of the configuration of a solar cell element according to the second embodiment.
  • FIG. 37 is a cross-sectional view that illustrates an example of the configuration of a solar cell element according to the third embodiment.
  • FIG. 38 is an enlarged cross-sectional view that roughly shows a portion XXXVIII of FIG. 36 in the configuration of the solar cell element according to the second embodiment and a portion XXXVIII of FIG. 37 in the configuration of the solar cell element according to the third embodiment.
  • FIG. 36 is a cross-sectional view that illustrates an example of the configuration of a solar cell element according to the second embodiment.
  • FIG. 38 is an enlarged cross-sectional view that roughly shows a portion XXXVIII of FIG. 36 in the configuration of the solar cell
  • FIG. 39 is a flowchart showing an example of a method for manufacturing a solar cell element according to the third embodiment.
  • FIG. 40 is a cross-sectional view that illustrates an example of the configuration of a solar cell element according to the fourth embodiment.
  • FIG. 41 is a cross-sectional view that illustrates an example of the configuration of a solar cell element according to the fifth embodiment.
  • FIG. 42 is a flowchart showing an example of a method for manufacturing a solar cell element according to the fifth embodiment.
  • FIG. 43 is a cross-sectional view that illustrates an example of the configuration of a back-contact type solar cell element.
  • FIG. 44 is a cross-sectional view that illustrates an example of the configuration of another back-contact type solar cell element.
  • solar cell elements that have a structure called POLO (polysilicon on oxide) in a region on the surface of a crystalline silicon substrate (also called a crystalline silicon substrate), or in a region located inside the crystalline silicon substrate and extending from the portion along the surface of the crystalline silicon substrate onto the crystalline silicon substrate.
  • This POLO structure includes a stacked structure of an extremely thin oxide film (also called an extremely thin oxide film) and a layer of polycrystalline silicon doped with an impurity element (also called a doped polysilicon layer).
  • a solar cell element that has a POLO structure is a TOPCon (Tunnel Oxide Passivated Contact) type solar cell element.
  • TOPCon type solar cell element is a solar cell element that includes a structure in which an extremely thin oxide film and a doped polysilicon layer of a first conductivity type (e.g., n-type) are stacked on a crystalline silicon substrate having a first conductivity type (e.g., n-type).
  • a first conductivity type e.g., n-type
  • TOPCon structure in solar cell elements include, for example, high passivation performance and the ability to selectively transmit carriers (also called carrier selectivity).
  • the TOPCon structure can improve the conversion efficiency of solar cell elements, which indicates the proportion of the energy of incident light that is converted into electrical energy.
  • a chemical vapor deposition (CVD) method can be used to form a doped polysilicon layer in a POLO structure such as a TOPCon structure.
  • CVD methods include low pressure chemical vapor deposition (LPCVD) and plasma enhanced chemical vapor deposition (PECVD).
  • the desired doped polysilicon layer can be formed, for example, by forming an intrinsic polycrystalline silicon layer (also called an i-type polysilicon layer) using the LPCVD method, doping this i-type polysilicon layer with an impurity element, and annealing the doped polycrystalline silicon layer (also called a polysilicon layer).
  • the desired doped polysilicon layer can also be formed, for example, by forming a polysilicon layer while doping an impurity element using the LPCVD method, and then annealing the doped polysilicon layer.
  • the polysilicon layer is formed on both sides of the crystalline silicon substrate. This requires complicated processing, such as a process to remove one of the unnecessary polysilicon layers formed on both sides of the crystalline silicon substrate, or a process to remove the mask after the polysilicon layer is formed on the second side of the crystalline silicon substrate with a mask provided on the first side of the crystalline silicon substrate.
  • the LPCVD method when used to form a polysilicon layer, it takes a long time to form a polysilicon layer of the desired thickness. In other words, the speed of film formation (also called the film formation rate) is low when the LPCVD method is used to form a polysilicon layer.
  • the time required to form a POLO structure such as a TOPCon structure can be shortened by forming a doped polysilicon layer using the PECVD method, which has a higher deposition rate than the LPCVD method and is capable of depositing a silicon layer (also called a silicon layer) on a desired side of a crystalline silicon substrate.
  • the productivity of solar cell elements including a POLO structure such as a TOPCon structure can be improved by forming a doped polysilicon layer using the PECVD method.
  • a silicon layer doped with an impurity element is formed on a desired surface side of a crystalline silicon substrate by using the PECVD method, this silicon layer becomes an amorphous silicon layer doped with an impurity element (also called a doped amorphous silicon layer).
  • an impurity element also called a doped amorphous silicon layer.
  • a doped polysilicon layer is formed by performing a high-temperature heat treatment on the doped amorphous silicon layer formed on a desired surface side of a crystalline silicon substrate by using the PECVD method, and crystallization of the doped amorphous silicon layer is advanced.
  • a gaseous raw material also called a raw material gas
  • hydrogen such as monosilane (SiH 4 ) gas, phosphine (PH 3 ) gas, and hydrogen (H 2 ) gas
  • a process also called hydrogenation
  • hydrogen is performed to bond hydrogen to the dangling bond of the silicon element in the doped amorphous silicon layer, and the silicon element in the doped amorphous silicon layer can be stabilized.
  • the hydrogen in the source gas can reach areas or defects in the interface between the ultra-thin oxide film and the doped amorphous silicon layer that have weak adhesion, in the form of hydrogen gas.
  • the ultra-thin oxide film can reduce the inflow of hydrogen into the crystalline silicon substrate. For this reason, the hydrogen gas can condense at the interface between the ultra-thin oxide film and the doped amorphous silicon layer, causing blisters to form.
  • hydrogen may be released from the doped amorphous silicon layer.
  • This release of hydrogen may occur when hydrogen bonded to silicon in the doped amorphous silicon layer is desorbed.
  • This hydrogen may then take the form of hydrogen gas and reach areas or defects in the interface between the extremely thin oxide film and the doped amorphous silicon layer that have weak adhesion.
  • the extremely thin oxide film may reduce the inflow of hydrogen to the crystalline silicon substrate.
  • the hydrogen gas may condense at the interface between the extremely thin oxide film and the doped amorphous silicon layer, causing blisters to occur.
  • the silicon layer may shrink due to the progression of bonding between silicon elements, which may increase the stress that may peel off the silicon layer from the extremely thin oxide film. This increase in stress also makes blisters more likely to occur.
  • the internal pressure of the blister may increase due to, for example, further condensation of hydrogen gas. This may cause the doped amorphous silicon layer, where crystallization has begun, to burst locally.
  • the doped polysilicon layer generated by crystallization of the doped amorphous silicon layer may have a local defect caused by the blister.
  • the local defect in the doped polysilicon layer may be considered as a type of defect in the doped polysilicon layer.
  • the unruptured blister may exist at the interface between the ultrathin oxide film and the doped polysilicon layer.
  • the defect in the POLO structure may include, for example, one or more defects among blisters existing at the interface between the ultrathin oxide film and the doped polysilicon layer and local defects in the doped polysilicon layer.
  • a solar cell element including a TOPCon structure which is a type of POLO, in which an extremely thin oxide film and a doped polysilicon layer of a first conductivity type (e.g., n-type) are stacked on a crystalline silicon substrate having a first conductivity type (e.g., n-type).
  • a solar cell element including a TOPCon structure which is a type of POLO, in which an extremely thin oxide film and a doped polysilicon layer of a first conductivity type (e.g., n-type) are stacked on a crystalline silicon substrate having a first conductivity type (e.g., n-type).
  • the high passivation performance of the TOPCon structure may be reduced. This may result in a reduction in the conversion efficiency of the solar cell element including the TOPCon structure.
  • a solar cell element including a POLO structure in which an extremely thin oxide film and a doped polysilicon layer of a first conductivity type (e.g., n-type) are stacked on a crystalline silicon substrate having a second conductivity type (e.g., p-type).
  • a first conductivity type e.g., n-type
  • a second conductivity type e.g., p-type
  • the region where the crystalline silicon substrate and the doped polysilicon layer are joined via the extremely thin oxide film also called the pn junction region
  • This may result in a decrease in the conversion efficiency of the solar cell element including the POLO structure.
  • the method for forming a doped amorphous silicon layer on an extremely thin oxide film is not limited to PECVD, and other methods such as vapor deposition can also be considered.
  • the inventors of this disclosure have therefore developed a technology to reduce defects in solar cell elements having a POLO structure formed using a doped amorphous silicon layer.
  • one direction along the thickness direction of the solar cell elements 1, 1A, 1B, 1C, 1D, 1E, and 1F (also called the first thickness direction) is the +Z direction
  • one direction perpendicular to the +Z direction is the +X direction
  • one direction perpendicular to both the +X direction and the +Z direction is the +Y direction.
  • the direction along the thickness direction of the solar cell elements 1, 1A, 1B, 1C, 1D, 1E, and 1F, opposite to the first thickness direction is defined as the -Z direction.
  • FIG. 1 An example of the structure of a solar cell element Fig. 1 is a cross-sectional view showing an example of the configuration of a solar cell element 1 according to the first embodiment.
  • Fig. 2 is an enlarged cross-sectional view showing a portion II of Fig. 1 in the configuration of the solar cell element 1 according to the first embodiment.
  • the solar cell element 1 has a plate-like shape with a surface 1f (also called the first element surface or front surface) facing the +Z direction and a surface 1b (also called the second element surface or back surface) facing the -Z direction.
  • the solar cell element 1 includes a silicon substrate 2 as a substrate.
  • the silicon substrate 2 includes crystalline silicon (also called crystalline silicon), such as single crystal or polycrystalline.
  • the silicon substrate 2 may be a crystalline silicon substrate.
  • the silicon substrate 2 has, for example, a first surface (also called a first main surface) 2f, a second surface (also called a second main surface) 2b on the opposite side to the first surface 2f, and an end surface connecting the first surface 2f and the second surface 2b.
  • the first surface 2f and the second surface 2b face in opposite directions in the thickness direction of the silicon substrate 2.
  • the thickness direction of the silicon substrate 2 may be a direction along the +Z direction as the first thickness direction, or a direction along the -Z direction as the second thickness direction.
  • the first surface 2f faces the +Z direction
  • the second surface 2b faces the -Z direction.
  • the direction along the +Z direction is also referred to as the upward direction or upward
  • the direction along the -Z direction is also referred to as the downward direction or downward.
  • the silicon substrate 2 has a first semiconductor region 21 as a first region which is a region of a semiconductor of a first conductivity type.
  • the silicon substrate 2 has a region (also called a second semiconductor region) 22 of a semiconductor of a second conductivity type different from the first conductivity type.
  • the silicon substrate 2 has a first semiconductor region 21 of crystalline silicon of the first conductivity type and a second semiconductor region 22 of crystalline silicon of the second conductivity type.
  • the first semiconductor region 21 is located on the second surface 2b side
  • the second semiconductor region 22 is located on the first surface 2f side.
  • the silicon substrate 2 is the first semiconductor region 21, and the region located inside the silicon substrate 2 and along the first surface 2f is the second semiconductor region 22.
  • the first conductivity type is n-type
  • the second conductivity type is p-type.
  • the n-type first semiconductor region 21 contains an n-type dopant (also called an n-type dopant).
  • the second semiconductor region 22 contains a p-type dopant (also called a p-type dopant).
  • a group 15 element such as phosphorus (P) is applied to the n-type dopant.
  • a group 13 element such as boron (B) is applied to the p-type dopant.
  • the concentration of the n-type dopant in the first semiconductor region 21 is set in the range of, for example, 1 ⁇ 10 15 atoms/cubic centimeter (atoms/cm 3 ) to 1 ⁇ 10 17 atoms/cm 3 .
  • the concentration of the p-type dopant in the second semiconductor region 22 is set in the range of, for example, 1 ⁇ 10 20 atoms/cm 3 to 1 ⁇ 10 22 atoms/cm 3 .
  • the thickness of the silicon substrate 2 is set to, for example, 100 micrometers ( ⁇ m) to 250 ⁇ m.
  • the shape of the silicon substrate 2 in a planar view is set to, for example, a rectangular or square shape with a side length of 20 millimeters (mm) to 210 mm.
  • the shape of the silicon substrate 2 in a planar view is the shape of the silicon substrate 2 when the silicon substrate 2 is viewed in the -Z direction or +Z direction.
  • the shape of the silicon substrate 2 in a planar view is not limited to a rectangular shape, and may be another polygonal shape or other shape.
  • the thickness of the second semiconductor region 22 is set to, for example, 0.1 ⁇ m to 2 ⁇ m.
  • a fine uneven structure (also called a texture structure) may be formed on the first surface 2f of the silicon substrate 2.
  • the shapes of the convex and concave portions of the texture structure may be, for example, pyramidal or spherical.
  • the height of the convex portions of the texture structure is set to, for example, 0.1 ⁇ m to 10 ⁇ m.
  • the height of the convex portion may be, for example, the distance between the bottom of the concave portion and the top of the convex portion in the +Z direction.
  • the interval between adjacent convex portions in the texture structure is set to, for example, 0.1 ⁇ m to 20 ⁇ m.
  • the interval between adjacent convex portions may be, for example, the distance between the tops of adjacent convex portions in the +Z direction perpendicularly.
  • Each layer located above the first surface 2f of the silicon substrate 2 of the solar cell element 1 may also have a shape that reflects the uneven structure of the underlying layer. In other words, each layer located above the first surface 2f of the silicon substrate 2 of the solar cell element 1 may also have an uneven structure. This uneven structure can reduce the light reflectance on the front surface 1f side of the solar cell element 1. As a result, the solar cell element 1 can efficiently capture light irradiated to the front surface 1f into the inside of the solar cell element 1.
  • the solar cell element 1 includes a silicon oxide film 3 as an oxide film on the second surface 2b side of the silicon substrate 2, and an n-type polysilicon layer 4 as a layer of polycrystalline silicon (also called a polysilicon layer) containing a dopant of a first conductivity type.
  • the solar cell element 1 also includes a first anti-reflection film 5 and a first electrode 6 on the back surface 1b side of the n-type polysilicon layer 4.
  • the silicon oxide film 3 is in contact with the first semiconductor region 21 of the silicon substrate 2.
  • the silicon oxide film 3 may be located on the surface of the second surface 2b of the silicon substrate 2, or may be located inside the silicon substrate 2 and along the second surface 2b.
  • the solar cell element 1 when the silicon oxide film 3 is located on the surface of the second surface 2b of the silicon substrate 2, the solar cell element 1 includes the silicon substrate 2, the silicon oxide film 3, and the n-type polysilicon layer 4.
  • the solar cell element 1 when the silicon oxide film 3 is located inside the silicon substrate 2 and along the second surface 2b, the solar cell element 1 includes the silicon substrate 2 including the silicon oxide film 3, and the n-type polysilicon layer 4.
  • the silicon oxide film 3 is located in a state where it covers the first semiconductor region 21 from the second surface 2b side.
  • the silicon oxide film 3 is a silicon oxide film.
  • the thickness direction of the silicon oxide film 3 may be the +Z direction as the first thickness direction, as in the thickness direction of the silicon substrate 2, or may be the -Z direction as the second thickness direction.
  • the thickness of the silicon oxide film 3 is set to, for example, 3 nanometers (nm) or less. This may cause a tunnel effect between the first semiconductor region 21 and the n-type polysilicon layer 4, which are positioned across the silicon oxide film 3.
  • the thickness of the silicon oxide film 3 may be, for example, 2 nm or less.
  • the lower limit of the thickness of the silicon oxide film 3 may be a thickness at which the presence of the silicon oxide film 3 can be confirmed by analysis using, for example, secondary ion mass spectrometry (SIMS).
  • SIMS secondary ion mass spectrometry
  • the n-type polysilicon layer 4 is in contact with the silicon oxide film 3.
  • the silicon oxide film 3 is in contact with each of the first semiconductor region 21 and the n-type polysilicon layer 4.
  • the n-type polysilicon layer 4 is located on the silicon oxide film 3. More specifically, the n-type polysilicon layer 4 is in contact with the surface of the silicon oxide film 3 opposite to the first semiconductor region 21.
  • the n-type polysilicon layer 4 is located in a state of covering the surface of the silicon oxide film 3 opposite to the first semiconductor region 21.
  • the silicon oxide film 3 is located between the first semiconductor region 21 and the n-type polysilicon layer 4.
  • the n-type polysilicon layer 4 is in contact with the silicon substrate 2. More specifically, for example, when the silicon oxide film 3 is located inside the silicon substrate 2 and along the second surface 2b, the n-type polysilicon layer 4 is in contact with the second surface 2b of the silicon substrate 2.
  • the n-type polysilicon layer 4 is a layer of polycrystalline silicon doped with an impurity element (also called a doped polysilicon layer). In the first embodiment, the n-type polysilicon layer 4 contains an n-type dopant as a dopant of the first conductivity type.
  • the n-type polysilicon layer 4 is a layer of n-type polycrystalline silicon.
  • a group 15 element such as phosphorus (P) is applied as the n-type dopant.
  • the concentration of the n-type dopant in the n-type polysilicon layer 4 is set in the range of, for example, 1 ⁇ 10 20 atoms/cm 3 to 1 ⁇ 10 22 atoms/cm 3 .
  • a high passivation performance can be realized by a TOPCon structure as a kind of POLO structure in which the first semiconductor region 21, the silicon oxide film 3, and the n-type polysilicon layer 4 are stacked in the described order.
  • the thickness direction of the n-type polysilicon layer 4 may be a direction along the +Z direction as a first thickness direction, like the thickness directions of the silicon substrate 2 and the silicon oxide film 3, or may be a direction along the ⁇ Z direction as a second thickness direction.
  • an arrow is attached to indicate a first thickness direction D1 as a direction from the surface of the n-type polysilicon layer 4 on the opposite side to the silicon substrate 2 toward the silicon substrate 2.
  • the thickness of the n-type polysilicon layer 4 is set in a range of, for example, several tens of nm to several hundreds of nm.
  • the thickness of the n-type polysilicon layer 4 may be set in a range of 30 nm to 250 nm.
  • the first anti-reflection film 5 is located on the back surface 1b of the solar cell element 1.
  • the first anti-reflection film 5 is located on the n-type polysilicon layer 4. More specifically, the first anti-reflection film 5 is located in a state where it covers almost the entire surface of the n-type polysilicon layer 4 opposite the silicon oxide film 3, except for the area where the first electrode 6 is located.
  • the first anti-reflection film 5 is, for example, a silicon nitride film.
  • the first anti-reflection film 5 has, for example, a role of protecting the n-type polysilicon layer 4 and a role of reducing the reflection of light on the back surface 1b of the solar cell element 1.
  • the thickness direction of the first anti-reflection film 5 may be a direction along the +Z direction as the first thickness direction, as with the respective thickness directions of the silicon substrate 2, the silicon oxide film 3, and the n-type polysilicon layer 4, or a direction along the -Z direction as the second thickness direction.
  • the thickness of the first anti-reflection film 5 is set, for example, in the range of several nm to 100 nm.
  • the first electrode 6 is located on the back surface 1b of the solar cell element 1.
  • the first electrode 6 has a role of collecting carriers generated by photoelectric conversion in response to light irradiation in the solar cell element 1 on the back surface 1b of the solar cell element 1 and extracting electricity to the outside of the solar cell element 1.
  • the first electrode 6 is located on the n-type polysilicon layer 4 and is located in a state of penetrating the first anti-reflection film 5. In other words, the first electrode 6 is in contact with the n-type polysilicon layer 4 inside the through hole (also called the first through hole) of the first anti-reflection film 5.
  • the form in which the first electrode 6 is located on the n-type polysilicon layer 4 may include a form in which the first electrode 6 reaches into a recess located on the first electrode 6 side of the n-type polysilicon layer 4.
  • the first through hole may be formed, for example, by a method such as irradiation of a laser beam or etching using a photolithography method, or may be formed by firing through (also called fire-through) the first anti-reflection film 5 when the first electrode 6 is formed.
  • the shape of the first electrode 6 in plan view may be, for example, a grid shape.
  • the first electrode 6 may have a form in which a plurality of first busbar electrodes each having a longitudinal direction along the +Y direction and a number of first finger electrodes each having a longitudinal direction along the +X direction and thinner than the first busbar electrodes cross each other.
  • the width of the first busbar electrodes is set, for example, in the range of 0.5 mm to 3 mm.
  • the width of the first finger electrodes is set, for example, in the range of 10 ⁇ m to 150 ⁇ m.
  • the interval between the many first finger electrodes is set, for example, in the range of 0.5 mm to 3 mm.
  • the thickness direction of the first electrode 6 may be the direction along the +Z direction as the first thickness direction, as well as the thickness directions of the silicon substrate 2, the silicon oxide film 3, the n-type polysilicon layer 4, and the first anti-reflection film 5, or may be the direction along the ⁇ Z direction as the second thickness direction.
  • the thickness of the first electrode 6 is set, for example, in the range of 5 ⁇ m to 50 ⁇ m.
  • the first electrode 6 contains, for example, a metal as a main component.
  • the main component here may mean that the content is 50% or more.
  • the metal as the main component of the first electrode 6 is, for example, any one of silver (Ag), copper (Cu), a metal mixture of aluminum (Al) and silver, and a metal mixture of titanium (Ti), lead (Pb), and silver.
  • the solar cell element 1 has a passivation film 7, a second anti-reflection film 8, and a second electrode 9 on the front surface 1f side of the silicon substrate 2.
  • the passivation film 7 is located on the first surface 2f of the silicon substrate 2. More specifically, the passivation film 7 is located in a state where it covers almost the entire surface of the first surface 2f of the silicon substrate 2 except for the region where the second electrode 9 is located. In other words, the passivation film 7 is in contact with the second semiconductor region 22 of the silicon substrate 2. For example, an aluminum oxide layer or a silicon oxide layer is applied to the passivation film 7.
  • the passivation film 7 has a role of reducing the recombination of minority carriers generated by photoelectric conversion in response to irradiation of light in the silicon substrate 2 by inactivating the first surface 2f of the silicon substrate 2.
  • the thickness direction of the passivation film 7 may be the direction along the +Z direction as the first thickness direction, as in the thickness direction of the silicon substrate 2, or the direction along the -Z direction as the second thickness direction.
  • the thickness of the passivation film 7 is set in the range of, for example, several nm to 100 nm.
  • the thickness of the passivation film 7 may be set, for example, in the range of several nm to 50 nm.
  • the second anti-reflection film 8 is located on the front surface 1f of the solar cell element 1.
  • the second anti-reflection film 8 is located on the passivation film 7. More specifically, the second anti-reflection film 8 is located in a state where it covers almost the entire surface of the passivation film 7 opposite to the silicon substrate 2.
  • the second anti-reflection film 8 is, for example, a silicon nitride film.
  • the second anti-reflection film 8, together with the passivation film 7, serves to reduce the reflectance of light irradiated to the front surface 1f of the solar cell element 1.
  • the thickness direction of the second anti-reflection film 8 may be the direction along the +Z direction as the first thickness direction, as with the thickness directions of the silicon substrate 2 and the passivation film 7, or may be the direction along the -Z direction as the second thickness direction.
  • the thickness of the second anti-reflection film 8 is set, for example, in the range of several nm to 100 nm.
  • the second electrode 9 is an electrode for collecting carriers generated by photoelectric conversion in response to irradiation of light in the solar cell element 1 on the front 1f side of the solar cell element 1 and extracting electricity to the outside of the solar cell element 1.
  • the second electrode 9 is located on the first surface 2f of the silicon substrate 2 and is located in a state in which it penetrates the second anti-reflection film 8 and the passivation film 7. In other words, the second electrode 9 is in contact with the first surface 2f inside a through hole (also called a second through hole) that penetrates the second anti-reflection film 8 and the passivation film 7.
  • the second through hole may be formed, for example, by a method such as irradiation of a laser beam or etching using a photolithography method, or may be formed by firing through the second anti-reflection film 8 and the passivation film 7 when the second electrode 9 is formed.
  • the shape of the second electrode 9 in a plan view may be, for example, a grid shape.
  • the second electrode 9 may have a configuration in which a plurality of second busbar electrodes each having a longitudinal direction along the +Y direction intersect with a plurality of second finger electrodes each having a longitudinal direction along the +X direction and thinner than the second busbar electrodes.
  • the width of the second busbar electrodes is set, for example, in the range of 0.5 mm to 3 mm.
  • the width of the second finger electrodes is set, for example, in the range of 10 ⁇ m to 150 ⁇ m.
  • the spacing between the plurality of second finger electrodes is set, for example, in the range of 0.5 mm to 3 mm.
  • the thickness of the second electrode 9 is set, for example, in the range of 5 ⁇ m to 50 ⁇ m.
  • the second electrode 9 contains, for example, a metal as a main component.
  • the metal as a main component of the second electrode 9 can be, for example, any of silver, copper, a metal mixture of aluminum and silver, and a metal mixture of titanium, lead, and silver.
  • Fig. 3 is a flow chart showing an example of a method for manufacturing the solar cell element 1 according to the first embodiment.
  • Each of Fig. 4 to Fig. 13 is a cross-sectional view showing an example of a configuration during the manufacturing process of the solar cell element 1 according to the first embodiment.
  • the solar cell element 1 can be manufactured by performing the processes of steps S1 to S8 in Fig. 3 in the order described above.
  • a silicon substrate 2 is prepared.
  • the silicon substrate 2 has a first surface 2f and a second surface 2b opposite to the first surface 2f.
  • a substrate of n-type crystalline silicon as a first conductive type is adopted.
  • the silicon substrate 2 contains, for example, a group 15 element such as phosphorus (P) as an n-type dopant.
  • concentration of the n-type dopant in the silicon substrate 2 is set in the range of, for example, 1 ⁇ 10 15 atoms/cm 3 to 1 ⁇ 10 17 atoms/cm 3.
  • the silicon substrate 2 can be obtained by slicing an ingot of n-type crystalline silicon produced using, for example, the Czochralski (CZ) method or a casting method to a thickness of 250 ⁇ m or less.
  • CZ Czochralski
  • a slight etching process may be performed on the cut surface of the silicon substrate 2 when the silicon substrate 2 is cut out from the silicon ingot.
  • an alkaline aqueous solution such as sodium hydroxide or potassium hydroxide
  • an acidic aqueous solution such as fluoronitric acid
  • a textured structure is formed on the first surface 2f of the silicon substrate 2.
  • the textured structure is formed over the entire area of the first surface 2f of the silicon substrate 2.
  • the textured structure can be formed, for example, by wet or dry etching of the first surface 2f of the silicon substrate 2.
  • Wet etching can be performed using, for example, an alkaline aqueous solution of sodium hydroxide or the like, or an acidic aqueous solution of fluoronitric acid or the like.
  • Dry etching can be performed using, for example, a reactive ion etching (RIE) method.
  • RIE reactive ion etching
  • a second semiconductor region 22 is formed in a portion located inside the silicon substrate 2 and along the first surface 2f having a textured structure.
  • the second semiconductor region 22 is a region of p-type crystalline silicon as a second conductive type.
  • the second semiconductor region 22 is, for example, a region containing a p-type dopant such as boron.
  • the surface of the silicon substrate 2 may be cleaned with an aqueous solution containing hydrofluoric acid.
  • the second semiconductor region 22 may be formed, for example, by using a vapor phase thermal diffusion method in which gaseous boron tribromide (BBr 3 ) is used as a diffusion source.
  • BBr 3 gaseous boron tribromide
  • boron tribromide boron trifluoride (BF 3 ), and boron trichloride (BCl 3 ) may be adopted as the diffusion source.
  • concentration of the p-type dopant in the second semiconductor region 22 is set in the range of, for example, 1 ⁇ 10 20 atoms/cm 3 to 1 ⁇ 10 22 atoms/cm 3.
  • the thickness of the second semiconductor region 22 is set in the range of, for example, 0.1 ⁇ m to 2 ⁇ m.
  • the second semiconductor region 22 is located in a portion along the first surface 2f, and the remaining portion excluding the second semiconductor region 22 is the first semiconductor region 21 as a region of n-type crystalline silicon as the first conductivity type.
  • the silicon substrate 2 becomes a substrate of crystalline silicon including the first semiconductor region 21 of n-type as the first conductivity type.
  • the second semiconductor region 22 when the second semiconductor region 22 is formed, if a region of p-type crystalline silicon (also called a p-type region) as the second conductivity type is formed in the portion located inside the silicon substrate 2 and along the second surface 2b, this p-type region is removed by etching using an aqueous solution of fluoronitric acid or the like. Also, for example, if boron glass is attached to the first surface 2f side of the silicon substrate 2 when the second semiconductor region 22 is formed, this boron glass is removed by etching.
  • a diffusion mask may be formed in advance on the second surface 2b side of the silicon substrate 2, the second semiconductor region 22 may be formed by vapor phase thermal diffusion or the like, and the diffusion mask may then be removed.
  • step S4 as an example of a first process, a process of forming a silicon oxide film 3 in contact with the first semiconductor region 21 of the silicon substrate 2 is performed.
  • the silicon oxide film 3 may be formed in a portion located inside the silicon substrate 2 and along the surface of the silicon substrate 2, or the silicon oxide film 3 may be formed on the surface of the silicon substrate 2. More specifically, the silicon oxide film 3 may be formed in a portion located inside the silicon substrate 2 and along the second surface 2b, or the silicon oxide film 3 may be formed on the second surface 2b of the silicon substrate 2. For example, as shown in FIG. 7, the silicon oxide film 3 is formed along the entire surface of the second surface 2b of the silicon substrate 2.
  • the silicon oxide film 3 may be formed by one or a combination of two or more of a chemical reaction method, a thermal reaction method, a chemical vapor deposition (CVD) method, an atomic layer deposition (ALD) method, a plasma reaction method, a steam oxidation method, and an ozone oxidation method.
  • the chemical reaction method may be, for example, a method in which the silicon substrate 2 is immersed in nitric acid at about 100 degrees Celsius (100° C.) to oxidize the surface of the silicon substrate 2.
  • the thermal reaction method may be a method in which the silicon substrate 2 is heated to a high temperature of 600° C. to 1100° C. in an oxygen atmosphere to modify the surface of the silicon substrate 2 into a silicon oxide film (also called a silicon oxide film).
  • the CVD method may be, for example, an LPCVD method.
  • LPCVD method When the LPCVD method is used to form the silicon oxide film 3, for example, a mask may be provided on the first surface 2 f of the silicon substrate 2, or the oxide film formed on the first surface 2 f side of the silicon substrate 2 may be removed with hydrofluoric acid or the like.
  • the plasma reaction method may be, for example, a plasma-enhanced atomic layer deposition (PEALD) method in which plasma is used to promote the reaction in the ALD method.
  • PEALD plasma-enhanced atomic layer deposition
  • the plasma reaction method may be, for example, a method in which plasma is used to promote the reaction in thermal oxidation.
  • the thickness of the silicon oxide film 3 may be set to, for example, 3 nm or less, or 2 nm or less.
  • the lower limit of the thickness of the silicon oxide film 3 may be a thickness at which the presence of the silicon oxide film 3 can be confirmed by analysis using, for example, SIMS.
  • the silicon oxide film 3 may be an extremely thin oxide film (also called an extremely thin oxide film).
  • step S5 an n-type polysilicon layer 4 is formed on the silicon oxide film 3.
  • step S5 the processes of steps S51 to S53 in FIG. 3 are performed in the order shown, so that the n-type polysilicon layer 4 can be formed.
  • step S51 as an example of the second step, a step of forming an intrinsic crystalline silicon layer 4a as a layer of intrinsic crystalline silicon (also referred to as a first layer) on the silicon oxide film 3 is carried out.
  • the intrinsic crystalline silicon layer 4a is formed on the surface of the silicon oxide film 3 opposite to the first semiconductor region 21.
  • the intrinsic crystalline silicon is crystalline silicon that does not substantially contain dopants.
  • the fact that the crystalline silicon does not substantially contain dopants means that the crystalline silicon may contain dopants at a concentration of 8 ⁇ 10 19 atoms/cm 3 or less that may be inevitably mixed in the film formation process of this crystalline silicon.
  • the intrinsic crystalline silicon layer 4a may be, for example, a layer of intrinsic polycrystalline silicon.
  • a layer of amorphous silicon that does not substantially contain dopants also called an intrinsic amorphous silicon layer or an i-type amorphous silicon layer
  • the intrinsic amorphous silicon layer is subjected to a heat treatment to advance the crystallization of the amorphous silicon, so that the intrinsic crystalline silicon layer 4a can be formed.
  • the temperature of this heat treatment is set, for example, within a range of 550°C to 1000°C.
  • the intrinsic crystalline silicon layer 4a is a layer of polysilicon that does not substantially contain dopants (also called an intrinsic polysilicon layer).
  • an intrinsic polysilicon layer For example, after the intrinsic crystalline silicon layer 4a is formed, the oxide film on each surface of the second semiconductor region 22 of the silicon substrate 2 formed up to the intrinsic crystalline silicon layer 4a and the intrinsic crystalline silicon layer 4a may be removed with an aqueous solution containing hydrofluoric acid.
  • the thickness of the intrinsic crystalline silicon layer 4a is set, for example, to 1 nm to 50 nm or less.
  • the intrinsic crystalline silicon layer 4a may be formed by, for example, stacking two or more films of intrinsic polysilicon.
  • step S52 as an example of the third step, a step is carried out in which an n-type amorphous silicon layer 4b is formed on the intrinsic crystalline silicon layer 4a as an amorphous silicon layer (also called a second layer) having a thickness greater than that of the intrinsic crystalline silicon layer 4a and containing an n-type dopant as a first conductive type dopant.
  • the n-type amorphous silicon layer 4b is formed by using, for example, a PECVD method.
  • the n-type amorphous silicon layer 4b is formed on the surface of the intrinsic crystalline silicon layer 4a on the opposite side to the silicon oxide film 3.
  • phosphorus (P) or the like is applied as the n-type dopant contained in the n-type amorphous silicon layer 4b.
  • the n-type amorphous silicon layer 4b can be formed by, for example, a PECVD method using monosilane (SiH 4 ) gas and phosphine (PH 3 ) gas as gaseous raw materials (also called raw material gas).
  • phosphine gas phosphorus trifluoride (PF 3 ) gas
  • PF 5 phosphorus pentafluoride
  • the thickness of the n-type amorphous silicon layer 4b is set to, for example, 20 nm to 200 nm.
  • the first electrode 6 is formed by firing through the first anti-reflection film 5
  • the thickness of the n-type amorphous silicon layer 4b is set to a certain thickness or more, such as 100 nm or more, the first electrode 6 does not fire through to the n-type polysilicon layer 4 when firing through the first anti-reflection film 5. This can reduce the reduction in the area on the surface of the silicon substrate 2 where the TOPCon structure, in which the first semiconductor region 21, the silicon oxide film 3, and the n-type polysilicon layer 4 are stacked in this order, exists.
  • the decrease in passivation performance due to the TOPCon structure can be reduced.
  • the thickness of the n-type amorphous silicon layer 4b is set to a certain thickness or less, such as 200 nm or less, the time required for forming the n-type amorphous silicon layer 4b can be shortened and the amount of material can be reduced, thereby improving the productivity of the solar cell element 1.
  • the thickness of the n-type amorphous silicon layer 4b is set to a certain thickness or less, such as 200 nm or less, the amount of light absorbed by the n-type polysilicon layer 4 can be reduced by reducing the thickness of the n-type polysilicon layer 4.
  • the concentration of the n-type dopant in the n-type amorphous silicon layer 4b is set to a range of, for example, 1 ⁇ 10 20 atoms/cm 3 to 1 ⁇ 10 22 atoms/cm 3. This ensures the concentration of the n-type dopant in the n-type polysilicon layer 4, thereby realizing high passivation performance due to the TOPCon structure in the solar cell element 1.
  • step S53 as an example of the fourth step, a step of forming an n-type polysilicon layer 4 by heat treatment is performed.
  • the intrinsic crystalline silicon layer 4a and the n-type amorphous silicon layer 4b stacked on the silicon oxide film 3 shown in FIG. 9 are transformed into an n-type polysilicon layer 4.
  • a heat treatment is performed to promote crystallization of the amorphous silicon of the n-type amorphous silicon layer 4b while diffusing the n-type dopant contained in the n-type amorphous silicon layer 4b toward the intrinsic crystalline silicon layer 4a and the silicon oxide film 3.
  • an n-type polysilicon layer 4 located on the silicon oxide film 3 and containing an n-type dopant can be generated from the intrinsic crystalline silicon layer 4a and the n-type amorphous silicon layer 4b.
  • the temperature of the heat treatment (also called the heat treatment temperature) is set, for example, within a range of 550°C to 1000°C.
  • the heat treatment temperature is set within the range of 700°C to 1000°C
  • the sheet resistance of the n-type polysilicon layer 4 can be reduced by activating the dopant.
  • the heat treatment temperature is set within the range of 700°C to 900°C, high passivation performance can be achieved by the TOPCon structure in the solar cell element 1.
  • an intrinsic crystalline silicon layer 4a having a thickness smaller than that of the n-type amorphous silicon layer 4b is formed on the silicon oxide film 3.
  • the intrinsic crystalline silicon layer 4a even if hydrogen bonded to silicon in the intrinsic amorphous silicon layer is desorbed by heat treatment for promoting crystallization of the intrinsic amorphous silicon layer, hydrogen can be released from the surface of the intrinsic amorphous silicon layer opposite to the silicon oxide film 3. This can reduce the aggregation of hydrogen gas at the interface between the silicon oxide film 3 and the intrinsic crystalline silicon layer 4a.
  • the thickness of the intrinsic amorphous silicon layer before it is transformed into the intrinsic crystalline silicon layer 4a by heat treatment is small, the increase in stress that may cause the silicon layer to peel off from the silicon oxide film 3 due to the contraction of the silicon layer can be reduced when the intrinsic amorphous silicon layer is transformed into the intrinsic crystalline silicon layer 4a by heat treatment. These factors can increase the adhesion between the silicon oxide film 3 and the intrinsic crystalline silicon layer 4a.
  • step S5 when the n-type polysilicon layer 4 is formed on the silicon oxide film 3, an intrinsic crystalline silicon layer 4a is formed on the silicon oxide film 3, and an n-type amorphous silicon layer 4b is further formed on the intrinsic crystalline silicon layer 4a, and then the n-type polysilicon layer 4 is generated from the intrinsic crystalline silicon layer 4a and the n-type amorphous silicon layer 4b by heat treatment.
  • This can reduce the occurrence of blisters at the interface between the silicon oxide film 3 and the n-type polysilicon layer 4, and can also reduce the occurrence of local defects in the n-type polysilicon layer 4 caused by these blisters.
  • the n-type polysilicon layer 4 is formed as a doped polysilicon layer by using a PECVD method or the like, the occurrence of blisters and the occurrence of local defects due to blisters can be reduced.
  • defects can be reduced in a solar cell element 1 having an example of a TOPCon structure, which is a type of POLO structure formed using a doped amorphous silicon layer. From another perspective, defects in the solar cell element 1 can be easily reduced.
  • the reduction in the area where the TOPCon structure, in which the first semiconductor region 21, the silicon oxide film 3, and the n-type polysilicon layer 4 are stacked in this order, exists on the surface of the silicon substrate 2 can be reduced.
  • the deterioration of passivation performance due to the TOPCon structure can be reduced in the solar cell element 1 according to the first embodiment.
  • the conversion efficiency of the solar cell element 1 can be easily improved.
  • a passivation film 7 is formed on the first surface 2f of the silicon substrate 2.
  • the passivation film 7 is formed over the entire surface of the second semiconductor region 22 opposite the first semiconductor region 21.
  • the aluminum oxide layer may be formed by the ALD method.
  • the silicon oxide layer may be formed by the PECVD method.
  • the first surface 2f of the silicon substrate 2 may be cleaned with an aqueous solution containing hydrofluoric acid.
  • an anti-reflection film is formed on each of the first surface 2f and the second surface 2b of the silicon substrate 2.
  • a first anti-reflection film 5 is formed over the entire surface of the n-type polysilicon layer 4 opposite the silicon substrate 2
  • a second anti-reflection film 8 is formed over the entire surface of the passivation film 7 opposite the silicon substrate 2.
  • the silicon nitride layer may be formed by the PECVD method.
  • each of the surface of the n-type polysilicon layer 4 opposite the silicon substrate 2 and the surface of the passivation film 7 opposite the silicon substrate 2 may be washed with an aqueous solution containing hydrofluoric acid.
  • step S8 electrodes are formed on the first surface 2f side and the second surface 2b side of the silicon substrate 2.
  • a first electrode 6 is formed on the second surface 2b side of the silicon substrate 2
  • a second electrode 9 is formed on the first surface 2f side of the silicon substrate 2.
  • a first metal paste 6p is applied to the first anti-reflection film 5 by a screen printing method or the like, and the first metal paste 6p is fired to form the first electrode 6.
  • a second metal paste 9p is applied to the second anti-reflection film 8 by a screen printing method or the like, and the second metal paste 9p is fired to form the second electrode 9.
  • each of the first metal paste 6p and the second metal paste 9p may contain a metal powder, an organic vehicle, and a glass frit.
  • the metal powder may be, for example, any of silver powder, copper powder, a powder in which aluminum powder and silver powder are mixed, and a powder in which titanium powder, lead powder, and silver powder are mixed.
  • the maximum temperature at which each of the first metal paste 6p and the second metal paste 9p is fired is set, for example, in the range of 600°C to 800°C. When the first metal paste 6p is fired, the glass frit of the first metal paste 6p melts and fires through the first anti-reflection film 5.
  • the first electrode 6 penetrates the first anti-reflection film 5 and is connected to the n-type polysilicon layer 4.
  • the glass frit of the second metal paste 9p melts and fires through the second anti-reflection film 8 and the passivation film 7.
  • the second electrode 9 penetrates the second anti-reflection film 8 and the passivation film 7 and is connected to the second semiconductor region 22.
  • FIG. 14 is a flow chart showing a method for producing samples of various specific examples of the TOPCon structure. By performing the processes of steps Sa1 to Sa5 in FIG. 14 in the order shown, samples of various specific examples of the TOPCon structure were manufactured.
  • the conditions under which samples of various specific examples described below were produced are an example of conditions adopted to confirm the feasibility and effects of the present disclosure, and the present disclosure is not limited to this example of conditions.
  • FIG. 15 is a flow chart showing a method for producing various reference example samples related to the TOPCon structure.
  • Various reference example samples related to the TOPCon structure were produced by performing the processes of steps Sb1 to Sb4 in FIG. 15 in the order shown.
  • the process flow of steps Sb1 to Sb4 in FIG. 15 corresponds to the process flow of steps Sa1 to Sa5 in FIG. 14 with step Sa3 deleted.
  • Each of the samples of the various specific examples relating to the TOPCon structure was fabricated by forming a silicon oxide film (silicon oxide film) corresponding to the silicon oxide film 3 on a crystalline silicon substrate (also called a crystalline silicon substrate) corresponding to the silicon substrate 2, and then forming an n-type polysilicon layer (also called an n-type polysilicon layer) corresponding to the n-type polysilicon layer 4 on the silicon oxide film, in the order described.
  • an n-type crystalline silicon substrate with an n-type dopant concentration of about 1 ⁇ 10 16 atoms/cm 3 or a p-type crystalline silicon substrate with a p-type dopant concentration of about 1 ⁇ 10 16 atoms/cm 3 was used.
  • the n-type dopant concentration in the n-type polysilicon layer was set to about 1 ⁇ 10 20 atoms/cm 3 to 1 ⁇ 10 22 atoms/cm 3.
  • n-type crystalline silicon substrate or a p-type crystalline silicon substrate is used as the crystalline silicon substrate, if other film formation conditions are the same, the defect occurrence state, characteristics, and dopant concentration distribution in the silicon oxide film and n-type polysilicon layer formed on the crystalline silicon substrate are assumed to be approximately the same, and samples of various specific examples and samples of various reference examples were produced. For example, when a p-type crystalline silicon substrate is used as the crystalline silicon substrate, a depletion layer is generated in the vicinity of the oxide film in the crystalline silicon substrate.
  • a p-type crystalline silicon substrate was used as the crystalline silicon substrate.
  • QSSPC Quasi Steady State Photo Conductance
  • an n-type crystalline silicon substrate was used as the crystalline silicon substrate.
  • iVoc is an index for evaluating the open circuit voltage of a solar cell element in a non-contact manner without electrodes being formed.
  • a crystalline silicon substrate was prepared (step Sa1 in FIG. 14).
  • a p-type crystalline silicon substrate (also simply referred to as a substrate) was prepared as the crystalline silicon substrate.
  • a monocrystalline silicon substrate doped with boron as a p-type dopant (also referred to as a p-type monocrystalline silicon substrate) was used as the p-type crystalline silicon substrate.
  • a wafer having one of its main surfaces corresponding to the second surface 2b in a mirror state was used as the p-type monocrystalline silicon substrate.
  • the mirror surface was realized by mechanical polishing for mirror finishing using an abrasive. The unevenness on the mirror surface was estimated to be several nm or less.
  • a silicon oxide film (silicon oxide film) was formed on the substrate (step Sa2 in FIG. 14).
  • hydrofluoric acid was used to clean the surface of the substrate, thereby removing the native oxide on the surface of the substrate.
  • the substrate was then immersed in nitric acid heated to 90°C to 100°C for 10 minutes, forming a silicon oxide film with a thickness of 2 nm or less on the surface of the substrate.
  • an intrinsic crystalline silicon layer was formed on the silicon oxide film (step Sa3 in FIG. 14).
  • an intrinsic amorphous silicon layer was formed by PECVD on the silicon oxide film formed on the mirror-like main surface side of the substrate.
  • the temperature of the substrate was set to 275°C, and monosilane gas was used as the source gas to form an intrinsic amorphous silicon layer having a thickness (also called the first thickness) ti1 of 10 nm.
  • the crystallization of the amorphous silicon in the amorphous silicon layer was advanced by heat treatment.
  • the intrinsic amorphous silicon layer was transformed into an intrinsic polysilicon layer. This heat treatment was performed in a nitrogen gas atmosphere in a heating furnace.
  • the substrate is carried into the heating furnace with the temperature in the heating furnace set to room temperature, the temperature in the heating furnace is raised from room temperature to 400°C at a rate of 100°C per hour, then held at 400°C for 30 minutes, and then lowered from 400°C to room temperature at a rate of 100°C per hour, after which the substrate is carried out of the heating furnace.
  • the substrate is carried into the heating furnace again with the temperature in the heating furnace set to 550°C, the temperature in the heating furnace is raised from 550°C to 850°C at a rate of 100°C per hour, then held at 850°C for 30 minutes, and then lowered from 850°C to 550°C at a rate of 100°C per hour, after which the substrate is carried out of the heating furnace.
  • the oxide film formed on the surface of the intrinsic crystalline silicon layer is removed by cleaning using hydrofluoric acid.
  • a region of the intrinsic crystalline silicon layer having a thickness of about 1 nm to 2 nm from the surface was removed by cleaning with hydrofluoric acid.
  • n-type amorphous silicon also called n-type amorphous silicon layer
  • a layer of amorphous silicon doped with phosphorus (P) as an n-type dopant also called P-doped amorphous silicon layer
  • P phosphorus
  • the temperature of the substrate was set to 275° C., and monosilane gas and phosphine gas diluted with hydrogen were used as source gases to form a P-doped amorphous silicon layer having a thickness (also called second thickness) tn2 of 50 nm.
  • the ratio of the flow rate of the monosilane gas to the flow rate of the phosphine gas was set to 40 [sccm]:20 [sccm] for the flow rate of the source gas introduced into the reaction chamber.
  • the unit of gas flow rate [sccm] is a volumetric flow rate under standard conditions of 1 atmospheric pressure and 0° C. (Standard Cubic Centimeter per Minute), that is, cubic centimeters per minute (cm 3 /min) under standard conditions.
  • an n-type polysilicon layer was formed by heat treatment (step Sa5 in FIG. 14).
  • the heat treatment promoted the crystallization of the amorphous silicon in the P-doped amorphous silicon layer, and P (phosphorus) as an n-type dopant contained in the P-doped amorphous silicon layer was diffused into the intrinsic crystalline silicon layer.
  • the intrinsic crystalline silicon layer and the P-doped amorphous silicon layer were transformed into a polysilicon layer doped with phosphorus (P) as an n-type polysilicon layer.
  • This heat treatment was performed in a nitrogen gas atmosphere in a heating furnace.
  • the substrate was carried into the heating furnace with the temperature in the heating furnace at room temperature, and the temperature in the heating furnace was raised from room temperature to 400° C. at a rate of 100° C. per hour, then held at 400° C. for 30 minutes, and then lowered from 400° C. to room temperature at a rate of 100° C. per hour, after which the substrate was taken out of the heating furnace.
  • the substrate is again loaded into the heating furnace, and the temperature inside the heating furnace is raised from 550°C to the maximum temperature (heat treatment temperature) T1 [°C] at a rate of 100°C per hour, then held at the maximum temperature (heat treatment temperature) T1 [°C] for 30 minutes, and then lowered from the maximum temperature (heat treatment temperature) T1 [°C] to 550°C at a rate of 100°C per hour, after which the substrate is removed from the heating furnace.
  • the heat treatment temperature T1 [°C] was set to 550°C, and thus a sample of specific example 1 relating to the TOPCon structure was obtained.
  • the heat treatment temperature T1 [°C] was set to 650°C, and thus a sample of specific example 2 relating to the TOPCon structure was obtained.
  • the heat treatment temperature T1 [°C] was set to 700°C, and thus a sample of specific example 3 relating to the TOPCon structure was obtained.
  • the heat treatment temperature T1 [°C] was set to 750°C, and thus a sample of specific example 4 relating to the TOPCon structure was obtained.
  • the heat treatment temperature T1 [°C] was set to 800°C, and thus a sample of specific example 5 relating to the TOPCon structure was obtained.
  • the heat treatment temperature T1 [°C] was set to 850°C, and thus a sample of specific example 6 relating to the TOPCon structure was obtained.
  • the heat treatment temperature T1 [°C] was set to 900°C, and thus a sample of specific example 7 relating to the TOPCon structure was obtained.
  • the heat treatment temperature T1 [°C] was set to 1000°C, resulting in a sample of specific example 8 relating to the TOPCon structure.
  • a crystalline silicon substrate was prepared (step Sb1 in FIG. 15).
  • a p-type crystalline silicon substrate (also simply referred to as a substrate) was prepared as the crystalline silicon substrate under the same conditions as step Sa1 in FIG. 14 in the fabrication of the samples of specific example 1, specific example 2, specific example 4, and specific example 6.
  • step Sb2 in FIG. 15 a silicon oxide film was formed on the substrate (step Sb2 in FIG. 15).
  • a silicon oxide film with a thickness of 2 nm or less was formed on the surface of the substrate under the same conditions as step Sa2 in FIG. 14 in the preparation of the samples of each of Specific Examples 1, 2, 4, and 6.
  • an n-type amorphous silicon layer was formed on the silicon oxide film using the PECVD method (step Sb3 in FIG. 15).
  • an amorphous silicon layer doped with phosphorus (P) as an n-type dopant (P-doped amorphous silicon layer) was formed on the silicon oxide film formed on the mirror-like main surface side of the substrate.
  • the conditions for forming the P-doped amorphous silicon layer were the same as those in step Sa4 in FIG. 14 for the preparation of the samples of each of Specific Examples 1, 2, 4, and 6.
  • a P-doped amorphous silicon layer with a thickness (second thickness) tn2 of 50 nm was formed.
  • an n-type polysilicon layer was formed by heat treatment (step Sb4 in FIG. 15).
  • the heat treatment promoted the crystallization of the amorphous silicon in the P-doped amorphous silicon layer.
  • the P-doped amorphous silicon layer was transformed into a polysilicon layer doped with phosphorus (P) as an n-type polysilicon layer.
  • the conditions for this heat treatment were the same as those for step Sa5 in FIG. 14 in the preparation of the samples of each of Specific Examples 1, 2, 4, and 6.
  • the heat treatment temperature T1 [°C] was set to 550°C, the same as in the preparation of the sample of specific example 1, to obtain the sample of Reference Example 1 relating to the TOPCon structure.
  • the heat treatment temperature T1 [°C] was set to 650°C, the same as in the preparation of the sample of specific example 2, to obtain the sample of Reference Example 2 relating to the TOPCon structure.
  • the heat treatment temperature T1 [°C] was set to 750°C, the same as in the preparation of the sample of specific example 4, to obtain the sample of Reference Example 4 relating to the TOPCon structure.
  • the heat treatment temperature T1 [°C] was set to 850°C, the same as in the preparation of the sample of specific example 6, to obtain the sample of Reference Example 6 relating to the TOPCon structure.
  • a crystalline silicon substrate was prepared (step Sa1 in FIG. 14).
  • an n-type crystalline silicon substrate (also simply referred to as a substrate) was prepared as the crystalline silicon substrate.
  • a single-crystal silicon substrate doped with phosphorus (P) as an n-type dopant (also referred to as an n-type single-crystal silicon substrate) was used as the n-type crystalline silicon substrate.
  • a wafer was obtained as an n-type single-crystal silicon substrate by cutting out an ingot of n-type single-crystal silicon produced by the CZ method.
  • etching was performed on the surface of the n-type single-crystal silicon substrate using potassium hydroxide, thereby removing mechanically damaged layers and contaminated layers on the cut surface of the wafer when it was cut out from the ingot.
  • An etching process was performed on the surface of the n-type single-crystal silicon substrate, thereby forming a texture structure.
  • an etching process was performed on the surface of the n-type single-crystal silicon substrate using a mixture of hydrofluoric acid, nitric acid, and acetic acid, thereby obtaining an n-type single-crystal silicon substrate having a surface with a slightly flattened texture structure.
  • the unevenness of the surface of the n-type single crystal silicon substrate a laser microscope was used to measure a 100 ⁇ m long region of the surface where the texture structure was slightly flattened, and the result was that the unevenness had a height of about 1.6 ⁇ m to 2.9 ⁇ m.
  • the height of the unevenness was defined as the difference in height between the top and bottom of the unevenness.
  • the n-type single crystal silicon substrate thus prepared was used to fabricate each of the samples of specific example 11 to specific example 15.
  • a silicon oxide film was formed on the substrate (step Sa2 in FIG. 14).
  • the surface of the substrate was cleaned using hydrofluoric acid to remove native oxides and contaminants on the surface of the substrate.
  • the substrate was then immersed in nitric acid heated to 90°C to 100°C for 10 minutes, forming a silicon oxide film with a thickness of 2 nm or less on the surface of the substrate.
  • an intrinsic crystalline silicon layer was formed on the silicon oxide film (step Sa3 in FIG. 14).
  • the PECVD method was used to sequentially form an intrinsic amorphous silicon layer on each of the silicon oxide films formed on both sides of the substrate.
  • the temperature of the substrate was set to 275°C, and monosilane gas was used as the raw material gas to form an intrinsic amorphous silicon layer having a thickness (first thickness) ti1 of 10 nm.
  • the crystallization of the amorphous silicon in the amorphous silicon layer was advanced by heat treatment.
  • the intrinsic amorphous silicon layer was transformed into an intrinsic polysilicon layer. This heat treatment was performed in a nitrogen gas atmosphere in a heating furnace.
  • the substrate is carried into the heating furnace with the temperature in the heating furnace set to room temperature, the temperature in the heating furnace is raised from room temperature to 400°C at a rate of 100°C per hour, then held at 400°C for 30 minutes, and then lowered from 400°C to room temperature at a rate of 100°C per hour, after which the substrate is carried out of the heating furnace.
  • the substrate is carried into the heating furnace again with the temperature in the heating furnace set to 550°C, the temperature in the heating furnace is raised from 550°C to 850°C at a rate of 100°C per hour, then held at 850°C for 30 minutes, and then lowered from 850°C to 550°C at a rate of 100°C per hour, after which the substrate is carried out of the heating furnace.
  • the oxide film formed on the surface of the intrinsic crystalline silicon layer is removed by cleaning using hydrofluoric acid.
  • a region of the intrinsic crystalline silicon layer having a thickness of about 1 nm to 2 nm from the surface was removed by cleaning with hydrofluoric acid.
  • an n-type amorphous silicon layer was formed in sequence on an intrinsic crystalline silicon layer on each of both sides of the substrate (step Sa4 in FIG. 14).
  • an amorphous silicon layer doped with phosphorus (P) as an n-type dopant (P-doped amorphous silicon layer) was formed.
  • the temperature of the substrate was set to 275° C., and monosilane gas and phosphine gas diluted with hydrogen were used as the source gases to form a P-doped amorphous silicon layer having a thickness (second thickness) tn2 of 150 nm.
  • the ratio of the flow rate of the monosilane gas to the flow rate of the phosphine gas was set to 40 [sccm]:20 [sccm] for the flow rate of the source gases introduced into the reaction chamber.
  • an n-type polysilicon layer was formed on each of both sides of the substrate by heat treatment (step Sa5 in FIG. 14).
  • the heat treatment promoted the crystallization of the amorphous silicon in the P-doped amorphous silicon layer, and diffused P (phosphorus) as an n-type dopant contained in the P-doped amorphous silicon layer into the intrinsic crystalline silicon layer.
  • the intrinsic crystalline silicon layer and the P-doped amorphous silicon layer were transformed into a polysilicon layer doped with phosphorus (P) as an n-type polysilicon layer.
  • This heat treatment was performed in a nitrogen gas atmosphere in a heating furnace.
  • the substrate is loaded into the heating furnace with the temperature in the heating furnace at room temperature, the temperature in the heating furnace is raised from room temperature to 400°C at a rate of 100°C per hour, then held at 400°C for 30 minutes, and then lowered from 400°C to room temperature at a rate of 100°C per hour, after which the substrate is removed from the heating furnace.
  • the substrate is loaded into the heating furnace again with the temperature in the heating furnace at 550°C, the temperature in the heating furnace is raised from 550°C to the maximum temperature (heat treatment temperature) T1 [°C] at a rate of 100°C per hour, then held at the maximum temperature (heat treatment temperature) T1 [°C] for 30 minutes, and then lowered from the maximum temperature (heat treatment temperature) T1 [°C] to 550°C at a rate of 100°C per hour, after which the substrate is removed from the heating furnace.
  • the heat treatment temperature T1 [°C] was set to 750°C, and thus a sample of specific example 11 relating to the TOPCon structure was obtained.
  • the heat treatment temperature T1 [°C] was set to 800°C, and thus a sample of specific example 12 relating to the TOPCon structure was obtained.
  • the heat treatment temperature T1 [°C] was set to 850°C, and thus a sample of specific example 13 relating to the TOPCon structure was obtained.
  • the heat treatment temperature T1 [°C] was set to 900°C, and thus a sample of specific example 14 relating to the TOPCon structure was obtained.
  • the heat treatment temperature T1 [°C] was set to 950°C, and thus a sample of specific example 15 relating to the TOPCon structure was obtained.
  • sample of Reference Example 13 was fabricated for comparison with the sample of Specific Example 13.
  • the flow of the fabrication method of the sample of Specific Example 13 was used as the basis, and the flow of the fabrication method of the sample of Reference Example 13 was a fabrication method flow that excluded the process of step Sa3 in Fig. 14 in which an intrinsic crystalline silicon layer is formed on a silicon oxide film.
  • the first thickness ti1 was set to 0 nm.
  • a crystalline silicon substrate was prepared (step Sb1 in FIG. 15).
  • an n-type crystalline silicon substrate (also simply referred to as a substrate) was prepared as the crystalline silicon substrate under the same conditions as step Sa1 in FIG. 14 in the preparation of the sample of specific example 13.
  • a silicon oxide film was formed on the substrate (step Sb2 in FIG. 15).
  • a silicon oxide film with a thickness of 2 nm or less was formed on the surface of the substrate under the same conditions as step Sa2 in FIG. 14 in the preparation of the sample of specific example 13.
  • an n-type amorphous silicon layer was formed on the silicon oxide film on both sides of the substrate using the PECVD method (step Sb3 in FIG. 15).
  • an amorphous silicon layer doped with phosphorus (P) as an n-type dopant (P-doped amorphous silicon layer) was formed on the silicon oxide film formed on both sides of the substrate.
  • the conditions for forming the P-doped amorphous silicon layer were the same as those for step Sa4 in FIG. 14 in the preparation of the sample of specific example 13.
  • a P-doped amorphous silicon layer with a thickness (second thickness) tn2 of 150 nm was formed.
  • an n-type polysilicon layer was formed on each of both surfaces of the substrate by heat treatment (step Sb4 in FIG. 15).
  • the heat treatment promoted the crystallization of the amorphous silicon in the P-doped amorphous silicon layer.
  • the P-doped amorphous silicon layer was transformed into a polysilicon layer doped with phosphorus (P) as an n-type polysilicon layer.
  • the conditions for this heat treatment were the same as those for step Sa5 in FIG. 14 in the preparation of the sample of specific example 13.
  • the heat treatment temperature T1 [°C] was set to 850°C, the same as in the preparation of the sample of specific example 13, and the sample of reference example 13 relating to the TOPCon structure was obtained.
  • a sample of specific example 21 was prepared based on the sample of specific example 11, in which the crystalline silicon substrate was changed from an n-type crystalline silicon substrate to a p-type crystalline silicon substrate.
  • the preparation method of the sample of specific example 21 was based on the preparation method of the sample of specific example 11, in which the n-type crystalline silicon substrate was changed to a p-type crystalline silicon substrate.
  • a sample of specific example 22 was prepared based on the sample of specific example 12, in which the crystalline silicon substrate was changed from an n-type crystalline silicon substrate to a p-type crystalline silicon substrate.
  • the preparation method of the sample of specific example 22 was based on the preparation method of the sample of specific example 12, in which the n-type crystalline silicon substrate was changed to a p-type crystalline silicon substrate.
  • a sample of specific example 23 was prepared based on the sample of specific example 13, in which the crystalline silicon substrate was changed from an n-type crystalline silicon substrate to a p-type crystalline silicon substrate.
  • the method for preparing the sample of the specific example 23 was based on the method for preparing the sample of the specific example 13, except that the n-type crystalline silicon substrate was changed to a p-type crystalline silicon substrate.
  • the sample of the specific example 24 was prepared based on the sample of the specific example 14, except that the crystalline silicon substrate was changed from an n-type crystalline silicon substrate to a p-type crystalline silicon substrate.
  • the method for preparing the sample of the specific example 24 was based on the method for preparing the sample of the specific example 14, except that the n-type crystalline silicon substrate was changed to a p-type crystalline silicon substrate.
  • the sample of the specific example 25 was prepared based on the sample of the specific example 15, except that the crystalline silicon substrate was changed from an n-type crystalline silicon substrate to a p-type crystalline silicon substrate.
  • the method for preparing the sample of the specific example 25 was based on the method for preparing the sample of the specific example 15, except that the n-type crystalline silicon substrate was changed to a p-type crystalline silicon substrate.
  • a single-crystal silicon substrate doped with boron as a p-type dopant (a p-type single-crystal silicon substrate) was used as the p-type crystalline silicon substrate.
  • Figure 16 shows an example of an image capturing the surface of the n-type polysilicon layer in the sample of Reference Example 6.
  • Figure 17 shows an example of an image capturing the surface of the n-type polysilicon layer in the sample of Specific Example 6.
  • Figure 18 shows an example of an image capturing the surface of the n-type polysilicon layer in the sample of Reference Example 13.
  • the circular black areas correspond to localized defects in the n-type polysilicon layer.
  • Figure 19 is a diagram showing an example of an image capturing the surface of the n-type polysilicon layer in the sample of Specific Example 13. As shown in Figure 19, in the sample of Specific Example 13, the presence of a textured structure was confirmed, but the presence of neither localized defects nor blisters in the n-type polysilicon layer was confirmed.
  • the manufacturing method of the solar cell element 1 of the first embodiment it is estimated that by performing steps 1 to 4 below, the occurrence of blisters when the n-type polysilicon layer 4 is formed as the doped polysilicon layer and the occurrence of local defects due to blisters can be reduced.
  • defects can be reduced in the solar cell element 1 having an example of a TOPCon structure, which is a type of POLO structure, formed using the n-type amorphous silicon layer 4b as the doped amorphous silicon layer. From another perspective, it is estimated that defects in the solar cell element 1 can be easily reduced.
  • a silicon oxide film 3 is formed as an oxide film in contact with the first semiconductor region 21 located inside a silicon substrate 2 as a crystalline silicon substrate including an n-type first semiconductor region 21 as a first region that is a region of a semiconductor of a first conductivity type, along the surface of the silicon substrate 2 or on the surface of the silicon substrate 2.
  • Step 2 An intrinsic crystalline silicon layer 4a is formed on the silicon oxide film 3 as the first layer of intrinsic crystalline silicon.
  • an n-type amorphous silicon layer 4b is formed as a second layer of amorphous silicon having a thickness greater than that of the intrinsic crystalline silicon layer 4a and containing phosphorus as an n-type dopant as the first conductivity type.
  • the n-type amorphous silicon layer 4b may be formed, for example, by using a PECVD method.
  • Step 4 A heat treatment is carried out to promote crystallization of the amorphous silicon of the n-type amorphous silicon layer 4b while diffusing the phosphorus contained in the n-type amorphous silicon layer 4b as an n-type dopant toward the intrinsic crystalline silicon layer 4a and the silicon oxide film 3.
  • an n-type polysilicon layer 4 is generated from the intrinsic crystalline silicon layer 4a and the n-type amorphous silicon layer 4b as a polysilicon layer located on the silicon oxide film 3 and containing phosphorus as an n-type dopant.
  • step 1 is an example of the first step of the present disclosure.
  • step 2 is an example of the second step of the present disclosure.
  • step 3 is an example of the third step of the present disclosure.
  • step 4 is an example of the fourth step of the present disclosure.
  • the solar cell element 1 manufactured by the method for manufacturing the solar cell element 1 according to the first embodiment in which steps 1 to 4 are performed can be said to be an element having either of the following configurations 5 and 6.
  • the solar cell element 1 comprises a silicon substrate 2, a silicon oxide film 3, and an n-type polysilicon layer 4.
  • the silicon substrate 2 has a first semiconductor region 21 as a first region which is a region of an n-type semiconductor as a first conductivity type.
  • the silicon oxide film 3 is an oxide film in contact with the first semiconductor region 21.
  • the n-type polysilicon layer 4 is in contact with the surface of the silicon oxide film 3 opposite the first semiconductor region 21 and is an n-type polysilicon layer containing phosphorus as an n-type dopant.
  • the n-type polysilicon layer 4 is a layer formed from the intrinsic crystalline silicon layer 4a and the n-type amorphous silicon layer 4b by performing a heat treatment on the intrinsic crystalline silicon layer 4a as a first layer of intrinsic crystalline silicon located on the silicon oxide film 3 and the n-type amorphous silicon layer 4b as a second layer of amorphous silicon located on the intrinsic crystalline silicon layer 4a, having a thickness greater than that of the intrinsic crystalline silicon layer 4a, and containing phosphorus as an n-type dopant.
  • This heat treatment is a process that progresses the crystallization of the amorphous silicon of the n-type amorphous silicon layer 4b while diffusing phosphorus as an n-type dopant contained in the n-type amorphous silicon layer 4b toward the intrinsic crystalline silicon layer 4a and the silicon oxide film 3.
  • the solar cell element 1 comprises a silicon substrate 2 and an n-type polysilicon layer 4.
  • the silicon substrate 2 has a first semiconductor region 21 as a first region which is a region of an n-type semiconductor as a first conductivity type.
  • the n-type polysilicon layer 4 is in contact with the silicon substrate 2 and is an n-type polysilicon layer containing phosphorus as an n-type dopant.
  • the silicon substrate 2 includes a silicon oxide film 3.
  • the silicon oxide film 3 is an oxide film located between the first semiconductor region 21 and the n-type polysilicon layer 4, and in contact with both the first semiconductor region 21 and the n-type polysilicon layer 4.
  • the n-type polysilicon layer 4 is a layer formed from the intrinsic crystalline silicon layer 4a and the n-type amorphous silicon layer 4b by performing a heat treatment on the intrinsic crystalline silicon layer 4a as a first layer of intrinsic crystalline silicon located on the silicon oxide film 3 and the n-type amorphous silicon layer 4b as a second layer of amorphous silicon located on the intrinsic crystalline silicon layer 4a, having a thickness greater than that of the intrinsic crystalline silicon layer 4a, and containing phosphorus as an n-type dopant.
  • This heat treatment is a process that progresses the crystallization of the amorphous silicon of the n-type amorphous silicon layer 4b while diffusing phosphorus as an n-type dopant contained in the n-type amorphous silicon layer 4b toward the intrinsic crystalline silicon layer 4a and the silicon oxide film 3.
  • the solar cell element 1 having any of the above configurations 5 and 6 has a configuration suitable for the manufacturing method of the solar cell element 1 that can reduce the occurrence of blisters and local defects caused by blisters when the n-type polysilicon layer 4 is formed as the doped polysilicon layer.
  • the solar cell element 1 having any of the above configurations 5 and 6 has a configuration suitable for the manufacturing method of the solar cell element 1 that can reduce the occurrence of blisters and local defects caused by blisters when the n-type polysilicon layer 4 is formed as the doped polysilicon layer by undergoing the formation of the n-type amorphous silicon layer 4b as the doped amorphous silicon layer and the heat treatment for crystallization of the n-type amorphous silicon layer 4b.
  • the solar cell element 1 having any of the above configurations 5 and 6 has a configuration suitable for the manufacturing method of the solar cell element 1 that can reduce defects in the solar cell element 1 having an example of a TOPCon structure, which is a type of POLO structure formed using a doped amorphous silicon layer. Therefore, it was understood that by adopting a solar cell element 1 having any one of the above configurations 5 and 6, defects in the solar cell element 1 having an example of a TOPCon structure, which is a type of POLO structure formed using a doped amorphous silicon layer, can be reduced. From another perspective, it was understood that defects in the solar cell element 1 can be easily reduced.
  • the distribution of the concentration of phosphorus as an n-type dopant in the first direction was measured using SIMS.
  • the first direction is a direction from the surface of the n-type polysilicon layer opposite to the substrate toward the substrate. This first direction may be one direction along the thickness direction of each of the n-type polysilicon layer, the silicon oxide film, and the substrate. This first direction may be a direction from the n-type polysilicon layer toward the substrate via the silicon oxide film.
  • the distribution of the concentration of phosphorus in the first direction was measured using SIMS, while avoiding blisters and local defects due to blisters in the n-type polysilicon layer.
  • Comparison between the sample of Specific Example 4 and the sample of Reference Example 4> 20 is a graph showing an example of a measurement result of the distribution of the concentration of phosphorus in a part of the first direction obtained by using SIMS for each sample of Specific Example 4 and Reference Example 4.
  • the distribution of the concentration of phosphorus as an n-type dopant in the first direction is shown for each sample of Specific Example 4 and Reference Example 4, from the region of the n-type polysilicon layer on the silicon oxide film side through the silicon oxide film to the semiconductor region of the substrate.
  • the graph of FIG. 20 shows the distribution of the concentration of phosphorus as an n-type dopant in the first direction for the region corresponding to the II part shown in FIG.
  • the horizontal axis indicates the position in the first direction
  • the vertical axis indicates the concentration of phosphorus.
  • the position in the first direction showing the maximum peak (also called the first peak) of the distribution of the concentration of phosphorus in the first direction is set to zero (0), which is the reference position of the horizontal axis.
  • the position in the first direction showing the maximum peak (first peak) in the distribution of the phosphorus concentration in the first direction corresponds to the position where the phosphorus concentration is maximum in the distribution of the phosphorus concentration in the first direction.
  • the direction from the n-type polysilicon layer toward the substrate is set as the positive direction
  • the direction from the substrate toward the n-type polysilicon layer is set as the negative direction.
  • the first direction which is the direction from the surface of the n-type polysilicon layer opposite to the substrate toward the substrate, is set as the positive direction.
  • the graph in Fig. 20 is a semi-logarithmic graph with a common logarithmic scale on the vertical axis.
  • the maximum peak (first peak) in the distribution of phosphorus concentration in the first direction was estimated to be located near the interface between the silicon oxide film and the n-type polysilicon layer by measuring the distribution of oxygen concentration in the first direction by SIMS.
  • the maximum peak (first peak) in the distribution of phosphorus concentration in the first direction was estimated to be caused by phosphorus segregation near the interface between the silicon oxide film and the n-type polysilicon layer.
  • the maximum peak (first peak) in the distribution of phosphorus concentration in the first direction was caused by phosphorus diffusing from the P-doped amorphous silicon layer toward the substrate during the heat treatment to advance the crystallization of the P-doped amorphous silicon layer, and a large amount of phosphorus segregating near the interface between the silicon oxide film and the n-type polysilicon layer.
  • the vicinity of the interface between the silicon oxide film and the n-type polysilicon layer could include a range of ⁇ 1 nm in the first direction based on the interface between the silicon oxide film and the n-type polysilicon layer.
  • the phosphorus concentration is almost constant in the range from approximately -25 nm to approximately -6.5 nm on the horizontal axis, whereas the phosphorus concentration clearly increases in the range from approximately -6.5 nm to approximately -2.5 nm on the horizontal axis (also called the first range).
  • the portion of the sample of Specific Example 4 that corresponds to the first range on the horizontal axis was presumed to be included in the portion of the n-type polysilicon layer of the sample of Specific Example 4 that was formed by transformation from the intrinsic crystalline silicon layer due to heat treatment.
  • the increase in phosphorus concentration in the first range occurred because, when the n-type polysilicon layer of the sample of Specific Example 4 was formed by heat treatment, the solid solubility of phosphorus in the intrinsic crystalline silicon layer formed on the silicon oxide film was higher than the solid solubility of phosphorus in the n-type amorphous silicon layer formed on the intrinsic crystalline silicon layer.
  • the increase in phosphorus concentration in the first range occurred because, during the heat treatment that advances the crystallization of the P-doped amorphous silicon layer, a large amount of phosphorus that diffuses from the P-doped amorphous silicon layer through the intrinsic crystalline silicon layer toward the silicon oxide film was dissolved in the intrinsic crystalline silicon layer, resulting in the increase in phosphorus concentration in the first range.
  • Each of Fig. 21 and Fig. 22 is a graph for explaining the characteristics of the phosphorus concentration distribution in a part of the first direction obtained by using SIMS for the sample of Specific Example 4.
  • the graph of Fig. 21 is a graph in which the curve Lr4 drawn by a thick dashed line showing the phosphorus concentration distribution in the first direction for the sample of Reference Example 4 is deleted from the graph of Fig. 20.
  • Fig. 22 shows a graph for recognizing the characteristics of the phosphorus concentration distribution in the first direction of the sample of Specific Example 4, taking into account noise components.
  • the graph of Fig. 22 like the graphs of Fig. 20 and Fig.
  • the horizontal axis indicates the position in the first direction
  • the vertical axis indicates the phosphorus concentration.
  • the position in the first direction showing the maximum peak (first peak) of the phosphorus concentration distribution in the first direction for the sample of Specific Example 4 is set to zero (0), which is the reference position of the horizontal axis.
  • the direction from the n-type polysilicon layer toward the substrate is taken as the positive direction
  • the direction from the substrate toward the n-type polysilicon layer is taken as the negative direction, as in the horizontal axes of the graphs in Fig. 20 and Fig. 21.
  • the first direction which is the direction from the surface of the n-type polysilicon layer opposite to the substrate toward the substrate, is taken as the positive direction.
  • the graph in Fig. 22 is a graph (also called a linear graph) with a normal scale for the phosphorus concentration on the vertical axis at the left end.
  • the distribution of the phosphorus concentration in a part of the first direction for the sample of Specific Example 4 is shown by a curve (strictly speaking, a broken line) Le4 drawn with a thick solid line.
  • the specific n-type dopant may mean one specific type of element among n-type dopants. For example, phosphorus is used as this one specific type of element.
  • a method for recognizing the characteristics of the distribution of the concentration of a specific n-type dopant (e.g., phosphorus) in a first direction of a sample, taking into account noise components.
  • the first recognition method the following four processes, [1] calculation of an index related to the noise components, [2] calculation of an approximation line, [3] calculation of a judgment line, and [4] peak recognition, are performed in the order listed, thereby recognizing the characteristics of the distribution of the concentration of a specific n-type dopant (e.g., phosphorus) in a first direction of a sample.
  • this first recognition method is adopted when recognizing the characteristics of the distribution of the concentration of a specific n-type dopant in a first direction for various samples.
  • SIMS can clarify the type of elements constituting the surface of a sample and the concentration of each element by analyzing the mass of secondary ions emitted from the surface of a sample when the surface of the sample is irradiated with primary ions.
  • SIMS can perform analysis in the depth direction of the sample because the surface of the sample is gradually scraped by irradiation with primary ions. Therefore, SIMS can obtain data on the distribution of the concentration of a specific n-type dopant in the first direction of a sample by measuring the concentration of a specific n-type dopant (e.g., phosphorus) while digging into the surface of a sample in a first direction.
  • a specific n-type dopant e.g., phosphorus
  • SIMS can obtain data on the distribution of the concentration of a specific n-type dopant in the first direction of a sample by sequentially measuring the concentration of a specific n-type dopant at multiple discrete positions in the first direction of a sample.
  • These discrete positions are positions (also called measurement positions) where the concentration of a specific n-type dopant is measured from the first position to the Mth position (M is a natural number) arranged in order in the first direction of a sample. Therefore, the discrete positions are the first measured position, the second measured position, the third measured position, ..., the Mth measured position, which are arranged in order in the first direction of one sample.
  • the concentration of a specific n-type dopant measured in order at the first to Mth measured positions in the first direction of one sample using SIMS is the concentration of a specific n-type dopant measured in the first to Mth order on one sample.
  • data indicating the distribution of the concentration of a specific n-type dopant in the first direction of one sample obtained using SIMS is composed of data of the concentration of a specific n-type dopant measured in the first direction of one sample in the first direction.
  • the concentration of the specific n-type dopant measured in a first direction of a single sample of the concentrations of M specific n-type dopants measured in order from 1st to Mth in the first direction of a single sample, the concentration of the specific n-type dopant measured at the nth position (n is an integer) and the concentration of the specific n-type dopant measured at the n+1th position are regarded as the concentrations of two specific n-type dopants adjacent to each other in the first direction.
  • ⁇ D1(n) as the ⁇ n-type dopant concentration is calculated by formula (1).
  • ⁇ D1(n)
  • D1(n) indicates the concentration of the specific n-type dopant measured n-th in the distribution of the concentration of the specific n-type dopant in the first direction of the sample.
  • D1(n+1) indicates the concentration of the specific n-type dopant measured n+1-th in the distribution of the concentration of the specific n-type dopant in the first direction of the sample.
  • the absolute value of the difference between the concentration of the specific n-type dopant measured n+1-th and the concentration of the specific n-type dopant measured n-th is calculated as the ⁇ n-type dopant concentration related to the concentration of the specific n-type dopant measured n-th.
  • the ⁇ P(n) as the ⁇ phosphorus concentration is calculated by formula (2).
  • P(n) indicates the nth measured phosphorus concentration in the distribution of phosphorus concentration in the first direction of the sample.
  • P(n+1) indicates the n+1th measured phosphorus concentration in the distribution of phosphorus concentration in the first direction of the sample.
  • the absolute value of the difference between the n+1th measured phosphorus concentration and the nth measured phosphorus concentration in the distribution of phosphorus concentration in the first direction of the sample is calculated as the ⁇ phosphorus concentration related to the nth measured phosphorus concentration.
  • the portion where the ⁇ n-type dopant concentration is finely wavy near zero (0) is presumed to indicate the variation in the measured value corresponding to the noise component in the distribution of the concentration of a specific n-type dopant (e.g., phosphorus) in the first direction of the sample.
  • a specific n-type dopant e.g., phosphorus
  • a base region (also called a base region) in which the concentration of the specific n-type dopant in the first direction is presumed to be substantially unchanged is set in a part of the region in the first direction where the ⁇ n-type dopant concentration is finely wavy near zero (0).
  • the maximum peak (first peak) is set as the reference, and the region from the position of the first distance to the position of the second distance is set as the base region.
  • the first distance may be set to, for example, 8 nm to 10 nm.
  • the second distance may be set to, for example, 15 nm to 25 nm.
  • the second distance may be set according to, for example, the thickness of the n-type polysilicon layer.
  • the second distance may be set to half the thickness of the n-type polysilicon layer or less.
  • the second distance may be set to 30 nm or less.
  • the second distance may be set to 15 nm or less.
  • the first distance is set to 10 nm and the second distance is set to 25 nm.
  • the standard deviation ⁇ of the ⁇ n-type dopant concentration in the base region is calculated as an index (also referred to as the first index) related to the noise component of the distribution of the concentration of a specific n-type dopant (e.g., phosphorus) in the first direction of the sample.
  • a line of a function (also called an approximation function) that is approximating the distribution of the concentration of a specific n-type dopant (e.g., phosphorus) in the first direction of the sample in the base region is calculated.
  • the line of the approximation function is calculated as a line (also called an approximation line) that is extended in the first direction of the sample in a form that exists not only in the base region but also in regions other than the base region.
  • a region from the base region in the first direction of the sample to a position showing the first peak may be adopted.
  • the region including the base region and the region other than the base region in the first direction of the sample for example, a region from a region on the silicon oxide film side of the n-type polysilicon layer in the first direction through the silicon oxide film to a semiconductor region of the substrate may be adopted.
  • the line of the approximation function a straight line of a linear function obtained by the least squares method may be adopted.
  • the approximation line is a straight line of a linear function.
  • a curve of a quadratic function obtained by the least squares method may be adopted.
  • the approximation line is a curve of a quadratic function.
  • the approximation line that approximates the distribution of the concentration of a specific n-type dopant (e.g., phosphorus) in the base region in the first direction of the sample is used as a reference, and a value m times the standard deviation ⁇ (m is a value between 3 and 4) is added as a first index to each concentration of the specific n-type dopant in the approximation line to calculate a line (also called a judgment line) in which the approximation line is shifted.
  • the approximation line is a straight line of a linear function
  • the judgment line is a straight line of a linear function.
  • the approximation line is a curved line of a quadratic function
  • the judgment line is a curved line of a quadratic function.
  • a significant peak of the concentration of the specific n-type dopant may be recognized for a portion where the concentration of the specific n-type dopant continues to exceed the judgment line in a range of a predetermined length or more in the first direction.
  • the predetermined length may be set to, for example, 1 nm, 1.5 nm, or 2 nm.
  • the distribution of the absolute value of the difference ( ⁇ phosphorus concentration) between two adjacent phosphorus concentrations in the first direction is shown by a curve (strictly speaking, a broken line) Le41 drawn with a thin solid line for the distribution of phosphorus concentration in the first direction of the sample of specific example 4.
  • the normal scale for ⁇ phosphorus concentration is given to the vertical axis at the right end.
  • an example is shown in which the region of the horizontal axis from ⁇ 10 nm to ⁇ 25 nm is set to the base region Ab0.
  • a straight line Le42 of a linear function as an example of an approximation line approximating the distribution of phosphorus concentration in the first direction of the sample of specific example 4 in the base region Ab0 is shown by a straight line drawn with a thin dashed line.
  • a straight line Le43 of a linear function as an example of a judgment line related to the phosphorus concentration in the sample of specific example 4 is shown by a straight line drawn with a thin dashed line.
  • the graph in FIG. 22 shows a straight line Le43, which is a linear function, as an example of a judgment line relating to the phosphorus concentration when m is set to 3.
  • the distribution of phosphorus concentration in the first direction in the region from the silicon oxide film side region of the n-type polysilicon layer through the silicon oxide film to the semiconductor region of the substrate for the sample of Specific Example 4 has a maximum peak (first peak) Pk1 and a second peak Pk2.
  • the second peak Pk2 was located at a position 3 nm or more away from the position showing the first peak Pk1 in the direction from the semiconductor region of the substrate through the silicon oxide film to the silicon oxide film side region of the n-type polysilicon layer.
  • the second peak Pk2 was located at a position about 3.5 nm away from the position showing the first peak Pk1 in the direction from the semiconductor region of the substrate through the silicon oxide film toward the silicon oxide film side region of the n-type polysilicon layer. Note that in each of the graphs in Figures 21 and 22, in the distribution of phosphorus concentration in the first direction, the second peak Pk2 was the peak that first appeared when moving further in the negative direction from -3 nm on the horizontal axis.
  • FIG. 23 is a graph for explaining the characteristics of the distribution of phosphorus concentration in a portion of the first direction obtained by using SIMS for the sample of Reference Example 4.
  • the graph in FIG. 23 is a graph (linear graph) with the normal scale for phosphorus concentration on the vertical axis at the left end.
  • a portion of the distribution of phosphorus concentration in the first direction for the sample of Reference Example 4 is shown by the curve (strictly speaking, a broken line) Lr4 drawn with a thick dashed line.
  • the straight line Lr42 of the linear function as an example of an approximation line approximating the distribution of phosphorus concentration in the first direction of the sample of Reference Example 4 in the base region Ab0 is shown by a straight line drawn with a thin dashed line.
  • the straight line Lr43 of the linear function as an example of a judgment line related to the phosphorus concentration for the sample of Reference Example 4 is shown by a straight line drawn with a thin dashed line.
  • the graph in FIG. 23 shows a straight line Lr43, which is a linear function, as an example of a judgment line relating to the phosphorus concentration when m is set to 3.
  • Comparison between the sample of Specific Example 6 and the sample of Reference Example 6> 24 is a graph showing an example of a measurement result of the distribution of the concentration of phosphorus in a part of the first direction obtained by using SIMS for each sample of Specific Example 6 and Reference Example 6.
  • the distribution of the concentration of phosphorus as an n-type dopant in the first direction is shown for each sample of Specific Example 6 and Reference Example 6, from the region on the silicon oxide film side of the n-type polysilicon layer through the silicon oxide film to the semiconductor region of the substrate.
  • the graph of FIG. 24 shows the distribution of the concentration of phosphorus as an n-type dopant in the first direction for the region corresponding to the II part shown in FIG.
  • the horizontal axis indicates the position in the first direction
  • the vertical axis indicates the concentration of phosphorus.
  • the position in the first direction showing the maximum peak (first peak) of the distribution of the concentration of phosphorus in the first direction is set to zero (0), which is the reference position of the horizontal axis.
  • the direction from the n-type polysilicon layer toward the substrate is taken as the positive direction
  • the direction from the substrate toward the n-type polysilicon layer is taken as the negative direction, as in the graph in Fig. 20.
  • a first direction which is the direction from the surface of the n-type polysilicon layer opposite to the substrate toward the substrate, is taken as the positive direction.
  • the graph in Fig. 24 is a semi-logarithmic graph with a common logarithmic scale on the vertical axis.
  • the maximum peak (first peak) in the distribution of phosphorus concentration in the first direction was estimated to be located near the interface between the silicon oxide film and the n-type polysilicon layer by measuring the distribution of oxygen concentration in the first direction by SIMS.
  • the maximum peak (first peak) in the distribution of phosphorus concentration in the first direction was estimated to be caused by phosphorus segregation near the interface between the silicon oxide film and the n-type polysilicon layer, as in each of the samples of Specific Example 4 and Reference Example 4 described above.
  • the phosphorus concentration is almost constant in the range from approximately -25 nm to approximately -7.5 nm on the horizontal axis, whereas the phosphorus concentration increases in the range from approximately -7.5 nm to approximately -3 nm on the horizontal axis (also called the second range).
  • the portion of the sample of Specific Example 6 that corresponds to the second range on the horizontal axis was presumed to be included in the portion of the n-type polysilicon layer in the sample of Specific Example 6 that was formed by transformation of the intrinsic crystalline silicon layer by heat treatment.
  • the increase in the phosphorus concentration in the second range for the sample of Specific Example 6 occurred because, like the sample of Specific Example 4 described above, when the n-type polysilicon layer in the sample of Specific Example 6 was formed by heat treatment, the solid solubility of phosphorus in the intrinsic crystalline silicon layer formed on the silicon oxide film was higher than the solid solubility of phosphorus in the n-type amorphous silicon layer formed on the intrinsic crystalline silicon layer.
  • the increase in phosphorus concentration in the first range for the sample of Specific Example 4 was greater than the increase in phosphorus concentration in the second range for the sample of Specific Example 6. It was presumed that this difference was caused by the fact that the heat treatment temperature T1 in the preparation of the sample of Specific Example 4, 750°C, was lower than the heat treatment temperature T1 in the preparation of the sample of Specific Example 6, 850°C.
  • Each of Fig. 25 and Fig. 26 is a graph for explaining the characteristics of the phosphorus concentration distribution in a part of the first direction obtained by using SIMS for the sample of Specific Example 6.
  • the graph of Fig. 25 is a graph in which the curve Lr6 drawn by a thick dashed line showing the phosphorus concentration distribution in the first direction for the sample of Reference Example 6 is deleted from the graph of Fig. 24.
  • Fig. 26 shows a graph for recognizing the characteristics of the phosphorus concentration distribution in the first direction of the sample of Specific Example 6, taking into account noise components.
  • the graph of Fig. 26 like the graphs of Fig. 24 and Fig.
  • the horizontal axis indicates the position in the first direction
  • the vertical axis indicates the phosphorus concentration.
  • the position in the first direction showing the maximum peak (first peak) of the phosphorus concentration distribution in the first direction for the sample of Specific Example 6 is set to zero (0), which is the reference position of the horizontal axis.
  • the direction from the n-type polysilicon layer toward the substrate is taken as the positive direction
  • the direction from the substrate toward the n-type polysilicon layer is taken as the negative direction, as in the horizontal axes of the graphs in Fig. 24 and Fig. 25.
  • the first direction which is the direction from the surface of the n-type polysilicon layer opposite to the substrate toward the substrate, is taken as the positive direction.
  • the graph in Fig. 26 is a graph (linear graph) with a normal scale for the phosphorus concentration on the vertical axis at the left end, as in the graph in Fig. 22.
  • a part of the distribution of the phosphorus concentration in the first direction of the sample of the specific example 6 is shown by a curve (strictly speaking, a broken line) Le6 drawn with a thick solid line.
  • the distribution of the absolute value of the difference ( ⁇ phosphorus concentration) between two adjacent phosphorus concentrations in the first direction for the distribution of phosphorus concentration in the first direction of the sample of specific example 6 is shown by a curve (strictly speaking, a broken line) Le61 drawn with a thin solid line.
  • the vertical axis at the right end is marked with a normal scale for ⁇ phosphorus concentration.
  • an example is shown in which the region of the horizontal axis from ⁇ 10 nm to ⁇ 25 nm is set in the base region Ab0.
  • a straight line Le62 of a linear function as an example of an approximation line approximating the distribution of phosphorus concentration in the first direction of the sample of specific example 6 in the base region Ab0 is shown by a straight line drawn with a thin dashed line.
  • a straight line Le63 of a linear function as an example of a judgment line related to the phosphorus concentration for the sample of specific example 6 is shown by a straight line drawn with a thin dashed line.
  • the graph in FIG. 26 shows a straight line Le63, which is a linear function, as an example of a judgment line relating to the phosphorus concentration when m is set to 3.
  • the distribution of phosphorus concentration in the first direction in the region from the silicon oxide film side region of the n-type polysilicon layer through the silicon oxide film to the semiconductor region of the substrate for the sample of Specific Example 6 has a maximum peak (first peak) Pk1 and a second peak Pk2.
  • the second peak Pk2 was located at a position 3 nm or more away from the position showing the first peak Pk1 in the direction from the semiconductor region of the substrate through the silicon oxide film to the silicon oxide film side region of the n-type polysilicon layer.
  • the second peak Pk2 was located at a position about 4.5 nm away from the position showing the first peak Pk1 in the direction from the semiconductor region of the substrate through the silicon oxide film toward the silicon oxide film side region of the n-type polysilicon layer. Note that in the graphs of Figures 25 and 26, in the distribution of phosphorus concentration in the first direction, the second peak Pk2 was the peak that first appeared when moving further in the negative direction from -3 nm on the horizontal axis.
  • FIG. 27 is a graph for explaining the characteristics of the phosphorus concentration distribution in a portion of the first direction obtained by using SIMS for the sample of Reference Example 6.
  • the graph of FIG. 27, like the graph of FIG. 23, is a graph (linear graph) with the normal scale for phosphorus concentration on the vertical axis at the left end.
  • a portion of the phosphorus concentration distribution in the first direction of the sample of Reference Example 6 is shown by the thick dashed curve (strictly speaking, a broken line) Lr6.
  • the straight line Lr62 of the linear function as an example of an approximation line approximating the distribution of phosphorus concentration in the first direction of the sample of Reference Example 6 in the base region Ab0 is shown by a straight line drawn with a thin dashed line.
  • the straight line Lr63 of the linear function as an example of a judgment line related to the phosphorus concentration for the sample of Reference Example 6 is shown by a straight line drawn with a thin dashed line.
  • the graph in FIG. 27 shows a straight line Lr63, which is a linear function, as an example of a judgment line relating to the phosphorus concentration when m is set to 3.
  • FIG. 28 is a graph showing an example of the measurement result of the distribution of the concentration of phosphorus in a part of the first direction obtained by using SIMS for each sample of Specific Example 2 and Reference Example 2.
  • the distribution of the concentration of phosphorus as an n-type dopant in the first direction is shown for the region from the silicon oxide film side region of the n-type polysilicon layer to the semiconductor region of the substrate through the silicon oxide film in each sample of Specific Example 2 and Reference Example 2.
  • the graph of FIG. 28 shows the distribution of the concentration of phosphorus as an n-type dopant in the first direction for the region corresponding to the II part shown in FIG.
  • the horizontal axis indicates the position in the first direction
  • the vertical axis indicates the concentration of phosphorus.
  • the position in the first direction showing the maximum peak (first peak) of the distribution of the concentration of phosphorus in the first direction is set to zero (0), which is the reference position of the horizontal axis.
  • the direction from the n-type polysilicon layer toward the substrate is taken as the positive direction
  • the direction from the substrate toward the n-type polysilicon layer is taken as the negative direction, as in the graphs in Fig. 20 and Fig. 24.
  • the first direction which is the direction from the surface of the n-type polysilicon layer opposite to the substrate toward the substrate, is taken as the positive direction.
  • the graph in Fig. 28 is a semi-logarithmic graph with a common logarithmic scale on the vertical axis, as in the graphs in Fig. 20 and Fig. 24.
  • the maximum peak (first peak) in the distribution of phosphorus concentration in the first direction was estimated to be located near the interface between the silicon oxide film and the n-type polysilicon layer by measuring the distribution of oxygen concentration in the first direction by SIMS.
  • the maximum peak (first peak) in the distribution of phosphorus concentration in the first direction was estimated to be caused by phosphorus segregation near the interface between the silicon oxide film and the n-type polysilicon layer, as in each of the samples of Specific Example 4, Specific Example 6, Reference Example 4, and Reference Example 6 described above.
  • the phosphorus concentration gradually decreases as it approaches the substrate in the range from approximately -25 nm to approximately -10 nm on the horizontal axis, whereas the phosphorus concentration clearly increases in the range from approximately -10 nm to approximately -2.5 nm on the horizontal axis (also called the third range).
  • the portion of the sample of Specific Example 2 that corresponds to the third range on the horizontal axis was presumed to be included in the portion of the n-type polysilicon layer in the sample of Specific Example 2 that was formed by transformation from the intrinsic crystalline silicon layer due to heat treatment.
  • the increase in the phosphorus concentration in the third range for the sample of Specific Example 2 occurred because, like the samples of Specific Examples 4 and 6 described above, when the n-type polysilicon layer in the sample of Specific Example 2 was formed by heat treatment, the solid solubility of phosphorus in the intrinsic crystalline silicon layer formed on the silicon oxide film was higher than the solid solubility of phosphorus in the n-type amorphous silicon layer formed on the intrinsic crystalline silicon layer.
  • Each of Fig. 29 and Fig. 30 is a graph for explaining the characteristics of the phosphorus concentration distribution in a part of the first direction obtained by using SIMS for the sample of Specific Example 2.
  • the graph of Fig. 29 is a graph in which the curve Lr2 drawn by a thick dashed line showing the phosphorus concentration distribution in the first direction for the sample of Reference Example 2 is deleted from the graph of Fig. 28.
  • Fig. 30 shows a graph for recognizing the characteristics of the phosphorus concentration distribution in the first direction of the sample of Specific Example 2, taking into account noise components.
  • the graph of Fig. 30 like the graphs of Fig. 28 and Fig.
  • the horizontal axis indicates the position in the first direction
  • the vertical axis indicates the phosphorus concentration.
  • the position in the first direction showing the maximum peak (first peak) of the phosphorus concentration distribution in the first direction for the sample of Specific Example 2 is set to zero (0), which is the reference position of the horizontal axis.
  • the direction from the n-type polysilicon layer toward the substrate is taken as the positive direction
  • the direction from the substrate toward the n-type polysilicon layer is taken as the negative direction, as in the horizontal axes of the graphs in Fig. 28 and Fig. 29.
  • the first direction which is the direction from the surface of the n-type polysilicon layer opposite to the substrate toward the substrate, is taken as the positive direction.
  • the graph in Fig. 30 is a graph (linear graph) with a normal scale for the phosphorus concentration on the vertical axis at the left end, as in the graphs in Fig. 22 and Fig. 26.
  • a part of the distribution of the phosphorus concentration in the first direction of the sample of the specific example 2 is shown by a curve (strictly speaking, a broken line) Le2 drawn with a thick solid line.
  • the distribution of the absolute value of the difference ( ⁇ phosphorus concentration) between two adjacent phosphorus concentrations in the first direction for the distribution of phosphorus concentration in the first direction of the sample of specific example 2 is shown by a curve (strictly speaking, a broken line) Le21 drawn with a thin solid line.
  • the vertical axis at the right end is marked with a normal scale for ⁇ phosphorus concentration.
  • an example is shown in which the region of the horizontal axis from ⁇ 10 nm to ⁇ 25 nm is set in the base region Ab0.
  • a straight line Le22 of a linear function as an example of an approximation line approximating the distribution of phosphorus concentration in the first direction of the sample of specific example 2 in the base region Ab0 is shown by a straight line drawn with a thin dashed dotted line.
  • a straight line Le23 of a linear function as an example of a judgment line relating to the phosphorus concentration is shown as a straight line drawn with a thin two-dot chain line.
  • a straight line Le23 of a linear function as an example of a judgment line relating to the phosphorus concentration when m times is set to 3 times is shown.
  • the distribution of phosphorus concentration in the first direction in the region from the silicon oxide film side region of the n-type polysilicon layer through the silicon oxide film to the semiconductor region of the substrate for the sample of Specific Example 2 has a maximum peak (first peak) Pk1 and a second peak Pk2.
  • the second peak Pk2 was located at a position 3 nm or more away from the position showing the first peak Pk1 in the direction from the semiconductor region of the substrate through the silicon oxide film to the silicon oxide film side region of the n-type polysilicon layer.
  • the second peak Pk2 was located at a position about 3.7 nm away from the position showing the first peak Pk1 in the direction from the semiconductor region of the substrate through the silicon oxide film toward the silicon oxide film side region of the n-type polysilicon layer. Note that in each of the graphs in Figures 29 and 30, in the distribution of phosphorus concentration in the first direction, the second peak Pk2 was the peak that first appeared when moving further in the negative direction from -3 nm on the horizontal axis.
  • FIG. 31 is a graph for explaining the characteristics of the distribution of phosphorus concentration in a part of the first direction obtained by using SIMS for the sample of Reference Example 2.
  • the graph of FIG. 31, like the graphs of FIG. 23 and FIG. 27, is a graph (linear graph) with the normal scale for phosphorus concentration on the vertical axis at the left end.
  • a part of the distribution of phosphorus concentration in the first direction of the sample of Reference Example 2 is shown by the curve (strictly speaking, a broken line) Lr2 drawn with a thick dashed line.
  • the distribution of the absolute value of the difference ( ⁇ phosphorus concentration) between two adjacent phosphorus concentrations in the first direction for the distribution of phosphorus concentration in the first direction of the sample of Reference Example 2 is shown by a curve (strictly speaking, a broken line) Lr21 drawn with a thin solid line.
  • the normal scale for ⁇ phosphorus concentration is given on the vertical axis at the right end.
  • an example is shown in which the region of the horizontal axis from ⁇ 10 nm to ⁇ 25 nm is set in the base region Ab0.
  • a straight line Lr22 of a linear function as an example of an approximation line approximating the distribution of phosphorus concentration in the first direction of the sample of Reference Example 2 in the base region Ab0 is shown by a straight line drawn with a thin dashed dotted line.
  • the straight line Lr23 of the linear function as an example of the judgment line for the phosphorus concentration is shown as a straight line drawn with a thin two-dot chain line.
  • the straight line Lr23 of the linear function as an example of the judgment line for the phosphorus concentration when m times is set to 3 times is shown.
  • Fig. 32 is a graph showing an example of a measurement result of a distribution of a concentration of phosphorus in a part of a first direction obtained by using SIMS on the sample of Specific Example 3.
  • Fig. 33 is a graph for explaining a feature of a distribution of a concentration of phosphorus in a part of a first direction obtained by using SIMS on the sample of Specific Example 3.
  • the graph of FIG. 32 shows the distribution of the concentration of phosphorus as an n-type dopant in the first direction in the region of the sample of specific example 3 from the silicon oxide film side region of the n-type polysilicon layer through the silicon oxide film to the semiconductor region of the substrate. From another perspective, the graph of FIG. 32 shows the distribution of the concentration of phosphorus as an n-type dopant in the first direction in the region of the sample of specific example 3 corresponding to part II shown in FIG. 2. In the graph of FIG. 32, the horizontal axis indicates the position in the first direction, and the vertical axis indicates the concentration of phosphorus. In the graph of FIG.
  • the position in the first direction showing the maximum peak (first peak) of the distribution of the concentration of phosphorus in the first direction for the sample of specific example 3 is set to zero (0), which is the reference position of the horizontal axis.
  • the direction from the n-type polysilicon layer toward the substrate is set to the positive direction
  • the direction from the substrate toward the n-type polysilicon layer is set to the negative direction, as in the graphs of FIG. 21, FIG. 25, and FIG. 29.
  • the first direction which is the direction from the surface of the n-type polysilicon layer opposite the substrate toward the substrate, is the positive direction.
  • the graph in Figure 32 is a semi-logarithmic graph with a common logarithmic scale on the vertical axis, just like the graphs in Figures 21, 25, and 29.
  • the maximum peak (first peak) in the distribution of phosphorus concentration in the first direction was estimated to be located near the interface between the silicon oxide film and the n-type polysilicon layer by measuring the distribution of oxygen concentration in the first direction by SIMS.
  • the maximum peak (first peak) in the distribution of phosphorus concentration in the first direction was estimated to be caused by phosphorus segregation near the interface between the silicon oxide film and the n-type polysilicon layer, as in the samples of Specific Examples 2, 4, and 6 described above.
  • the phosphorus concentration gradually decreases as it approaches the substrate in the range from approximately -25 nm to approximately -10 nm on the horizontal axis, whereas it was confirmed that the phosphorus concentration increases in the range from approximately -10 nm to approximately -3 nm on the horizontal axis (also called the fourth range).
  • the portion of the sample of Specific Example 3 that corresponds to the fourth range on the horizontal axis was presumed to be included in the portion of the n-type polysilicon layer in the sample of Specific Example 3 that was formed by transformation from the intrinsic crystalline silicon layer due to heat treatment.
  • the increase in the phosphorus concentration in the fourth range for the sample of Specific Example 3 occurred because, like the samples of Specific Examples 2, 4, and 6 described above, when the n-type polysilicon layer in the sample of Specific Example 3 was formed by heat treatment, the solid solubility of phosphorus in the intrinsic crystalline silicon layer formed on the silicon oxide film was higher than the solid solubility of phosphorus in the n-type amorphous silicon layer formed on the intrinsic crystalline silicon layer.
  • FIG. 33 shows a graph for recognizing the characteristics of the phosphorus concentration distribution in the first direction of the sample of specific example 3, taking into account noise components.
  • the horizontal axis indicates the position in the first direction
  • the vertical axis indicates the phosphorus concentration.
  • the position in the first direction showing the maximum peak (first peak) of the phosphorus concentration distribution in the first direction for the sample of specific example 3 is set to zero (0), which is the reference position of the horizontal axis.
  • the horizontal axis of the graph of FIG. 33 as in the horizontal axis of the graph of FIG.
  • the direction from the n-type polysilicon layer toward the substrate is set to the positive direction
  • the direction from the substrate toward the n-type polysilicon layer is set to the negative direction.
  • the first direction which is the direction from the surface of the n-type polysilicon layer opposite to the substrate toward the substrate, is set to the positive direction.
  • the graph in Figure 33 like the graphs in Figures 22, 26, and 30, is a graph (linear graph) with the normal scale for phosphorus concentration on the leftmost vertical axis.
  • a portion of the distribution of phosphorus concentration in the first direction of the sample of specific example 3 is shown by the curve (strictly speaking, a broken line) Le3 drawn with a thick solid line.
  • the distribution of the absolute value of the difference ( ⁇ phosphorus concentration) between two adjacent phosphorus concentrations in the first direction for the distribution of phosphorus concentration in the first direction of the sample of specific example 3 is shown by a curve (strictly speaking, a broken line) Le31 drawn with a thin solid line.
  • the vertical axis at the right end is marked with a normal scale for ⁇ phosphorus concentration.
  • an example is shown in which the region of the horizontal axis from ⁇ 10 nm to ⁇ 25 nm is set in the base region Ab0.
  • a straight line Le32 of a linear function as an example of an approximation line approximating the distribution of phosphorus concentration in the first direction of the sample of specific example 3 in the base region Ab0 is shown by a straight line drawn with a thin dashed line.
  • a straight line Le33 of a linear function as an example of a judgment line relating to the phosphorus concentration is shown as a straight line drawn with a thin two-dot chain line.
  • a straight line Le33 of a linear function as an example of a judgment line relating to the phosphorus concentration when m times is set to 3 times is shown.
  • the distribution of phosphorus concentration in the first direction in the region from the silicon oxide film side region of the n-type polysilicon layer of the sample of Specific Example 3 through the silicon oxide film to the semiconductor region of the substrate had a maximum peak (first peak) Pk1 and a second peak Pk2.
  • the second peak Pk2 was located at a position 3 nm or more away from the position showing the first peak Pk1 in the direction from the semiconductor region of the substrate through the silicon oxide film to the silicon oxide film side region of the n-type polysilicon layer.
  • the second peak Pk2 was located at a position about 6.2 nm away from the position showing the first peak Pk1 in the direction from the semiconductor region of the substrate through the silicon oxide film toward the silicon oxide film side region of the n-type polysilicon layer. Note that in each of the graphs in Figures 32 and 33, in the distribution of phosphorus concentration in the first direction, the second peak Pk2 was the peak that first appeared when moving further in the negative direction from -3 nm on the horizontal axis.
  • Fig. 34 is a graph showing an example of a measurement result of the distribution of the concentration of phosphorus in a part in the first direction obtained by using SIMS for the sample of Specific Example 5.
  • Fig. 35 is a graph for explaining the characteristics of the distribution of the concentration of phosphorus in a part in the first direction obtained by using SIMS for the sample of Specific Example 5.
  • the graph of FIG. 34 shows the distribution of the concentration of phosphorus as an n-type dopant in the first direction in the region of the sample of specific example 5 from the silicon oxide film side region of the n-type polysilicon layer through the silicon oxide film to the semiconductor region of the substrate. From another perspective, the graph of FIG. 34 shows the distribution of the concentration of phosphorus as an n-type dopant in the first direction in the region of the sample of specific example 5 corresponding to part II shown in FIG. 2. In the graph of FIG. 34, the horizontal axis indicates the position in the first direction, and the vertical axis indicates the concentration of phosphorus. In the graph of FIG.
  • the position in the first direction showing the maximum peak (first peak) of the distribution of the concentration of phosphorus in the first direction for the sample of specific example 5 is set to zero (0), which is the reference position of the horizontal axis.
  • the direction from the n-type polysilicon layer toward the substrate is set to the positive direction
  • the direction from the substrate toward the n-type polysilicon layer is set to the negative direction, as in the graphs of FIG. 21, FIG. 25, FIG. 29, and FIG. 32.
  • the first direction which is the direction from the surface of the n-type polysilicon layer opposite the substrate toward the substrate, is the positive direction.
  • the graph in Figure 34 is a semi-log graph with a common logarithmic scale on the vertical axis, just like the graphs in Figures 21, 25, 29, and 32.
  • the maximum peak (first peak) in the distribution of phosphorus concentration in the first direction was estimated to be located near the interface between the silicon oxide film and the n-type polysilicon layer by measuring the distribution of oxygen concentration in the first direction by SIMS.
  • the maximum peak (first peak) in the distribution of phosphorus concentration in the first direction was estimated to be caused by phosphorus segregation near the interface between the silicon oxide film and the n-type polysilicon layer, as in the samples of Specific Examples 2, 3, 4, and 6 described above.
  • the phosphorus concentration is almost constant in the range from approximately -25 nm to approximately -9 nm on the horizontal axis, whereas the phosphorus concentration increases in the range from approximately -9 nm to approximately -3 nm on the horizontal axis (also called the fifth range).
  • the portion of the sample of Specific Example 5 that corresponds to the fifth range on the horizontal axis was presumed to be included in the portion of the n-type polysilicon layer in the sample of Specific Example 5 that was formed by transformation of the intrinsic crystalline silicon layer by heat treatment.
  • the increase in the phosphorus concentration in the fifth range for the sample of Specific Example 5 occurred because, like the samples of Specific Examples 2, 3, 4, and 6 described above, when the n-type polysilicon layer in the sample of Specific Example 5 was formed by heat treatment, the solid solubility of phosphorus in the intrinsic crystalline silicon layer formed on the silicon oxide film was higher than the solid solubility of phosphorus in the n-type amorphous silicon layer formed on the intrinsic crystalline silicon layer.
  • FIG. 35 shows a graph for recognizing the characteristics of the phosphorus concentration distribution in the first direction of the sample of specific example 5, taking into account noise components.
  • the horizontal axis indicates the position in the first direction
  • the vertical axis indicates the phosphorus concentration.
  • the position in the first direction showing the maximum peak (first peak) of the phosphorus concentration distribution in the first direction for the sample of specific example 5 is set to zero (0), which is the reference position of the horizontal axis.
  • the horizontal axis of the graph of FIG. 35 as in the horizontal axis of the graph of FIG.
  • the direction from the n-type polysilicon layer toward the substrate is set to the positive direction
  • the direction from the substrate toward the n-type polysilicon layer is set to the negative direction.
  • the first direction which is the direction from the surface of the n-type polysilicon layer opposite to the substrate toward the substrate, is set to the positive direction.
  • the graph in Figure 35 like the graphs in Figures 22, 26, 30, and 33, is a graph (linear graph) with the normal scale for phosphorus concentration on the leftmost vertical axis.
  • a portion of the distribution of phosphorus concentration in the first direction of the sample of specific example 5 is shown by the curve (strictly speaking, a broken line) Le5 drawn with a thick solid line.
  • a straight line Le52 of a linear function as an example of an approximation line approximating the distribution of phosphorus concentration in the first direction of the sample of specific example 5 in the base region Ab0 is shown by a straight line drawn with a thin dashed line.
  • a straight line Le53 of a linear function as an example of a judgment line relating to the phosphorus concentration is shown as a straight line drawn with a thin two-dot chain line.
  • a straight line Le53 of a linear function as an example of a judgment line relating to the phosphorus concentration when m times is set to 3 times is shown.
  • the distribution of phosphorus concentration in the first direction in the region from the silicon oxide film side region of the n-type polysilicon layer of the sample of Specific Example 5 through the silicon oxide film to the semiconductor region of the substrate had a maximum peak (first peak) Pk1 and a second peak Pk2.
  • the second peak Pk2 was located at a position 3 nm or more away from the position showing the first peak Pk1 in the direction from the semiconductor region of the substrate through the silicon oxide film to the silicon oxide film side region of the n-type polysilicon layer.
  • the second peak Pk2 was located at a position about 6.3 nm away from the position showing the first peak Pk1 in the direction from the semiconductor region of the substrate through the silicon oxide film toward the silicon oxide film side region of the n-type polysilicon layer. Note that in each of the graphs in Figures 34 and 35, in the distribution of phosphorus concentration in the first direction, the second peak Pk2 was the peak that first appeared when moving further in the negative direction from -3 nm on the horizontal axis.
  • the solar cell element 1 comprises a silicon substrate 2, a silicon oxide film 3, and an n-type polysilicon layer 4.
  • the silicon substrate 2 has a first semiconductor region 21 as a first region which is a region of n-type semiconductor as a first conductivity type.
  • the silicon oxide film 3 is an oxide film in contact with the first semiconductor region 21.
  • the n-type polysilicon layer 4 is in contact with the surface of the silicon oxide film 3 opposite the first semiconductor region 21 and is an n-type polysilicon layer containing phosphorus as an n-type dopant.
  • the n-type polysilicon layer 4 includes a region (also referred to as an oxide film side region) 41 as a second region on the side of the silicon oxide film 3 that is in contact with the silicon oxide film 3.
  • the distribution of the concentration of phosphorus as an n-type dopant in the first thickness direction D1 as the direction from the surface of the n-type polysilicon layer 4 on the side opposite the silicon substrate 2 toward the silicon substrate 2 has a maximum first peak Pk1 and a second peak Pk2.
  • the second peak Pk2 is present at a position 3 nm or more away from the position showing the first peak Pk1 in the direction from the first semiconductor region 21 through the silicon oxide film 3 toward the oxide film side region 41.
  • the solar cell element 1 comprises a silicon substrate 2 and an n-type polysilicon layer 4.
  • the silicon substrate 2 has a first semiconductor region 21 as a first region which is a region of n-type semiconductor as a first conductivity type.
  • the n-type polysilicon layer 4 is an n-type polysilicon layer that is in contact with the silicon substrate 2 and contains phosphorus as an n-type dopant.
  • the silicon substrate 2 includes a silicon oxide film 3.
  • the silicon oxide film 3 is an oxide film that is located between the first semiconductor region 21 and the n-type polysilicon layer 4 and is in contact with both the first semiconductor region 21 and the n-type polysilicon layer 4.
  • the n-type polysilicon layer 4 includes a region (oxide film side region) 41 as a second region on the side of the silicon oxide film 3 that is in contact with the silicon oxide film 3.
  • the distribution of the concentration of phosphorus as an n-type dopant in the first thickness direction D1 as the direction from the surface of the n-type polysilicon layer 4 on the side opposite the silicon substrate 2 toward the silicon substrate 2 has a maximum first peak Pk1 and a second peak Pk2.
  • the second peak Pk2 is present at a position 3 nm or more away from the position showing the first peak Pk1 in the direction from the first semiconductor region 21 through the silicon oxide film 3 toward the oxide film side region 41.
  • the solar cell element 1 having any of the above configurations 1 and 2 has a configuration suitable for the manufacturing method of the solar cell element 1 that can reduce the occurrence of blisters and local defects caused by blisters when the n-type polysilicon layer 4 as the doped polysilicon layer is formed.
  • the solar cell element 1 having any of the above configurations 1 and 2 has a configuration suitable for the manufacturing method of the solar cell element 1 that can reduce the occurrence of blisters and local defects caused by blisters when the n-type polysilicon layer 4 as the doped polysilicon layer is formed by undergoing the deposition of the n-type amorphous silicon layer 4b as the doped amorphous silicon layer and the heat treatment for crystallization of the n-type amorphous silicon layer 4b.
  • the solar cell element 1 having any of the above configurations 1 and 2 has a configuration suitable for the manufacturing method of the solar cell element 1 that can reduce defects in the solar cell element 1 having an example of a TOPCon structure, which is a type of POLO structure formed using a doped amorphous silicon layer. Therefore, it was understood that by adopting a solar cell element 1 having either of the above configurations 1 and 2, defects in the solar cell element 1 having an example of a TOPCon structure, which is a type of POLO structure formed using a doped amorphous silicon layer, can be reduced. From another perspective, it was understood that defects in the solar cell element 1 can be easily reduced.
  • the distribution of the concentration of phosphorus as an n-type dopant in the first thickness direction D1 which is the direction from the surface of the n-type polysilicon layer 4 opposite the silicon substrate 2 toward the silicon substrate 2, in the region from the oxide film side region 41 of the n-type polysilicon layer 4 through the silicon oxide film 3 to the first semiconductor region 21 may be the result of measurement using, for example, SIMS, as described above.
  • the oxide film side region 41 may be the region closest to the silicon oxide film 3 among the N regions.
  • N may be, for example, two, three, or any number equal to or greater than four.
  • the any number equal to or greater than four may be six.
  • the oxide film side region 41 may be a region of the n-type polysilicon layer 4 that is 10 nm or less away from the silicon oxide film 3.
  • the second peak Pk2 may be located at a position 3 nm to 10 nm away from the position showing the first peak Pk1 in the direction from the first semiconductor region 21 toward the oxide film side region 41 via the silicon oxide film 3.
  • the second peak Pk2 may be located at a position 3 nm to 8 nm away from the position showing the first peak Pk1, or may be located at a position 3 nm to 7 nm away from the position showing the first peak Pk1 in the direction from the first semiconductor region 21 toward the oxide film side region 41 via the silicon oxide film 3.
  • the sheet resistance of the n-type polysilicon layer of each of the samples of Specific Example 1 and Specific Example 2 was a high value, up to several kiloohms per square ( ⁇ / ⁇ ).
  • the sheet resistance of the n-type polysilicon layer of the sample of Specific Example 3 was about 236 ⁇ / ⁇ .
  • the sheet resistance of the n-type polysilicon layer of the sample of Specific Example 5 was about 179 ⁇ / ⁇ .
  • the sheet resistance of the n-type polysilicon layer of the sample of Specific Example 7 was about 35 ⁇ / ⁇ .
  • the sheet resistance of the n-type polysilicon layer of the sample of Specific Example 8 was about 16 ⁇ / ⁇ .
  • the sheet resistance of the n-type polysilicon layer of the sample of specific example 21 was about 100 ⁇ / ⁇ .
  • the sheet resistance of the n-type polysilicon layer of the sample of specific example 22 was about 85 ⁇ / ⁇ .
  • the sheet resistance of the n-type polysilicon layer of the sample of specific example 23 was about 71 ⁇ / ⁇ .
  • the sheet resistance of the n-type polysilicon layer of the sample of specific example 24 was about 59 ⁇ / ⁇ .
  • the sheet resistance of the n-type polysilicon layer of the sample of specific example 25 was about 18 ⁇ / ⁇ .
  • the sheet resistance of the n-type polysilicon layer was reduced due to sufficient activation of the n-type dopant. Therefore, in the manufacturing method of the solar cell element 1 according to the first embodiment described above, it was estimated that the conversion efficiency of the solar cell element 1 can be improved by setting the heat treatment temperature during the formation of the n-type polysilicon layer 4 within the range of 700°C to 1000°C.
  • the carrier lifetime and iVoc of each of the samples from Specific Example 11 to Specific Example 15 and Reference Example 13 were measured using a pseudo-steady-state photoconductivity measurement device (QSSPC) manufactured by Sinton.
  • QSSPC pseudo-steady-state photoconductivity measurement device
  • the carrier lifetime was 71 microseconds ( ⁇ s) and the iVoc was 626 millivolts (mV).
  • the carrier lifetime was 1544 ⁇ s and the iVoc was 716 mV.
  • the carrier lifetime was 2573 ⁇ s and the iVoc was 727 mV.
  • the carrier lifetime was 4289 ⁇ s and the iVoc was 737 mV.
  • the carrier lifetime was 1546 ⁇ s and the iVoc was 714 mV.
  • the carrier lifetime was 39 ⁇ s and the iVoc was 624 mV.
  • the passivation performance of the TOPCon structure which is a type of POLO structure
  • the conversion efficiency of the solar cell element 1 can be improved.
  • the sample of specific example 15 had a carrier lifetime of about 39 ⁇ s or more and an iVoc of 624 mV, whereas the samples of specific examples 11 to 14 had a carrier lifetime of 1544 ⁇ s or more and an iVoc of 714 mV or more. Therefore, it was estimated that the passivation performance of the TOPCon structure, which is a type of POLO structure, was superior to that of the sample of specific example 15 for each of the samples of specific examples 11 to 14. As a result, it was estimated that the silicon oxide film 3 can be more stable when the heat treatment temperature during the formation of the n-type polysilicon layer is set within the range of 700°C to 900°C rather than when it is set to 950°C.
  • the conversion efficiency of the solar cell element 1 can be improved by setting the heat treatment temperature during the formation of the n-type polysilicon layer 4 to 700°C to 900°C.
  • the manufacturing method of the solar cell element 1 according to the first embodiment includes, for example, steps 1, 2, 3, and 4.
  • a silicon oxide film 3 is formed on a portion located inside a silicon substrate 2 as a substrate of crystalline silicon including an n-type first semiconductor region 21 as a first region that is a region of a semiconductor of a first conductivity type and along the surface of the silicon substrate 2 or on the surface of the silicon substrate 2, the silicon oxide film 3 being in contact with the first semiconductor region 21.
  • an intrinsic crystalline silicon layer 4a as a first layer of intrinsic crystalline silicon is formed on the silicon oxide film 3.
  • an n-type amorphous silicon layer 4b is formed on the intrinsic crystalline silicon layer 4a as a second layer of amorphous silicon having a thickness greater than that of the intrinsic crystalline silicon layer 4a and containing phosphorus as an n-type dopant as a first conductivity type.
  • a heat treatment is performed to promote crystallization of the amorphous silicon of the n-type amorphous silicon layer 4b while diffusing phosphorus as an n-type dopant contained in the n-type amorphous silicon layer 4b toward the intrinsic crystalline silicon layer 4a and the silicon oxide film 3.
  • the n-type polysilicon layer 4 is generated from the intrinsic crystalline silicon layer 4a and the n-type amorphous silicon layer 4b as a polysilicon layer located on the silicon oxide film 3 and containing phosphorus as an n-type dopant.
  • the manufacturing method of the solar cell element 1 according to the first embodiment has a feature that when the n-type polysilicon layer 4 is formed on the silicon oxide film 3, the intrinsic crystalline silicon layer 4a is formed on the silicon oxide film 3, and the n-type amorphous silicon layer 4b is further formed on the intrinsic crystalline silicon layer 4a, and then the n-type polysilicon layer 4 is generated from the intrinsic crystalline silicon layer 4a and the n-type amorphous silicon layer 4b by heat treatment.
  • This can reduce the occurrence of blisters when the n-type polysilicon layer 4 is formed as a doped polysilicon layer, as well as the occurrence of local defects due to blisters.
  • defects can be reduced in the solar cell element 1 having an example of a TOPCon structure, which is a type of POLO structure formed using the n-type amorphous silicon layer 4b as a doped amorphous silicon layer. From another perspective, defects in the solar cell element 1 can be easily reduced.
  • the solar cell element 1 according to the first embodiment has, for example, the following configuration 1, configuration 2, configuration 5, or configuration 6 described above.
  • the solar cell element 1 comprises a silicon substrate 2, a silicon oxide film 3, and an n-type polysilicon layer 4.
  • the silicon substrate 2 has a first semiconductor region 21 as a first region which is a region of n-type semiconductor as a first conductivity type.
  • the silicon oxide film 3 is an oxide film in contact with the first semiconductor region 21.
  • the n-type polysilicon layer 4 is in contact with the surface of the silicon oxide film 3 opposite the first semiconductor region 21 and is an n-type polysilicon layer containing phosphorus as an n-type dopant.
  • the n-type polysilicon layer 4 includes a region (oxide film side region) 41 as a second region on the side of the silicon oxide film 3 that is in contact with the silicon oxide film 3.
  • the distribution of the concentration of phosphorus as an n-type dopant in the first thickness direction D1 as the direction from the surface of the n-type polysilicon layer 4 on the side opposite the silicon substrate 2 toward the silicon substrate 2 has a maximum first peak Pk1 and a second peak Pk2.
  • the second peak Pk2 is present at a position 3 nm or more away from the position showing the first peak Pk1 in the direction from the first semiconductor region 21 through the silicon oxide film 3 toward the oxide film side region 41.
  • the solar cell element 1 comprises a silicon substrate 2 and an n-type polysilicon layer 4.
  • the silicon substrate 2 has a first semiconductor region 21 as a first region which is a region of n-type semiconductor as a first conductivity type.
  • the n-type polysilicon layer 4 is an n-type polysilicon layer that is in contact with the silicon substrate 2 and contains phosphorus as an n-type dopant.
  • the silicon substrate 2 includes a silicon oxide film 3.
  • the silicon oxide film 3 is an oxide film that is located between the first semiconductor region 21 and the n-type polysilicon layer 4 and is in contact with both the first semiconductor region 21 and the n-type polysilicon layer 4.
  • the n-type polysilicon layer 4 includes a region (oxide film side region) 41 as a second region on the side of the silicon oxide film 3 that is in contact with the silicon oxide film 3.
  • the distribution of the concentration of phosphorus as an n-type dopant in the first thickness direction D1 as the direction from the surface of the n-type polysilicon layer 4 on the side opposite the silicon substrate 2 toward the silicon substrate 2 has a maximum first peak Pk1 and a second peak Pk2.
  • the second peak Pk2 is present at a position 3 nm or more away from the position showing the first peak Pk1 in the direction from the first semiconductor region 21 through the silicon oxide film 3 toward the oxide film side region 41.
  • the solar cell element 1 comprises a silicon substrate 2, a silicon oxide film 3, and an n-type polysilicon layer 4.
  • the silicon substrate 2 has a first semiconductor region 21 as a first region which is a region of an n-type semiconductor as a first conductivity type.
  • the silicon oxide film 3 is an oxide film in contact with the first semiconductor region 21.
  • the n-type polysilicon layer 4 is in contact with the surface of the silicon oxide film 3 opposite the first semiconductor region 21 and is an n-type polysilicon layer containing phosphorus as an n-type dopant.
  • the n-type polysilicon layer 4 is a layer formed from the intrinsic crystalline silicon layer 4a and the n-type amorphous silicon layer 4b by performing a heat treatment on the intrinsic crystalline silicon layer 4a as a first layer of intrinsic crystalline silicon located on the silicon oxide film 3 and the n-type amorphous silicon layer 4b as a second layer of amorphous silicon located on the intrinsic crystalline silicon layer 4a, having a thickness greater than that of the intrinsic crystalline silicon layer 4a, and containing phosphorus as an n-type dopant.
  • This heat treatment is a process that progresses the crystallization of the amorphous silicon of the n-type amorphous silicon layer 4b while diffusing phosphorus as an n-type dopant contained in the n-type amorphous silicon layer 4b toward the intrinsic crystalline silicon layer 4a and the silicon oxide film 3.
  • the solar cell element 1 comprises a silicon substrate 2 and an n-type polysilicon layer 4.
  • the silicon substrate 2 has a first semiconductor region 21 as a first region which is a region of an n-type semiconductor as a first conductivity type.
  • the n-type polysilicon layer 4 is in contact with the silicon substrate 2 and is an n-type polysilicon layer containing phosphorus as an n-type dopant.
  • the silicon substrate 2 includes a silicon oxide film 3.
  • the silicon oxide film 3 is an oxide film located between the first semiconductor region 21 and the n-type polysilicon layer 4, and in contact with both the first semiconductor region 21 and the n-type polysilicon layer 4.
  • the n-type polysilicon layer 4 is a layer formed from the intrinsic crystalline silicon layer 4a and the n-type amorphous silicon layer 4b by performing a heat treatment on the intrinsic crystalline silicon layer 4a as a first layer of intrinsic crystalline silicon located on the silicon oxide film 3 and the n-type amorphous silicon layer 4b as a second layer of amorphous silicon located on the intrinsic crystalline silicon layer 4a, having a thickness greater than that of the intrinsic crystalline silicon layer 4a, and containing phosphorus as an n-type dopant.
  • This heat treatment is a process that progresses the crystallization of the amorphous silicon of the n-type amorphous silicon layer 4b while diffusing phosphorus as an n-type dopant contained in the n-type amorphous silicon layer 4b toward the intrinsic crystalline silicon layer 4a and the silicon oxide film 3.
  • the solar cell element 1 having the configuration 1, the configuration 2, the configuration 5, or the configuration 6 can be manufactured by the manufacturing method of the solar cell element 1 according to the first embodiment.
  • the solar cell element 1 is manufactured by the manufacturing method of the solar cell element 1 according to the first embodiment, the occurrence of blisters and the occurrence of local defects due to blisters when the n-type polysilicon layer 4 is formed as the doped polysilicon layer can be reduced.
  • defects can be reduced in the solar cell element 1 having an example of a TOPCon structure, which is a type of POLO structure formed by using the n-type amorphous silicon layer 4b as the doped amorphous silicon layer.
  • the manufacturing method of the solar cell element 1 according to the first embodiment was a manufacturing method for forming a TOPCon structure, which is a type of POLO structure, in which the first semiconductor region 21, the silicon oxide film 3, and the n-type polysilicon layer 4 are stacked in the order described above on the second surface 2b side of the silicon substrate 2.
  • a TOPCon structure which is a type of POLO structure, in which the first semiconductor region 21, the silicon oxide film 3, and the n-type polysilicon layer 4 are stacked in the order described above on the second surface 2b side of the silicon substrate 2.
  • the manufacturing method of this solar cell element 1 had a feature that, when the n-type polysilicon layer 4 is formed on the silicon oxide film 3, an intrinsic crystalline silicon layer 4a is formed on the silicon oxide film 3, and an n-type amorphous silicon layer 4b is further formed on the intrinsic crystalline silicon layer 4a, and then the n-type polysilicon layer 4 is generated from the intrinsic crystalline silicon layer 4a and the n-type amorphous silicon layer 4b by heat treatment.
  • the manufacturing method of the solar cell element of the present disclosure is not limited to this.
  • the solar cell element may include various forms of POLO structures different from the solar cell element 1 according to the first embodiment.
  • the solar cell element 1 according to the first embodiment includes a TOPCon structure in which an n-type first region, an oxide film, and an n-type polysilicon layer are stacked in the order described above as an example of a POLO structure, but the solar cell element of the present disclosure is not limited to this.
  • the manufacturing method of the solar cell element of the present disclosure is not limited to a method of manufacturing a solar cell element 1 including a TOPCon structure, which is a type of POLO structure in which an n-type first region, an oxide film, and an n-type polysilicon layer are stacked in the order described above.
  • the manufacturing method of the solar cell element 1 according to the first embodiment may be appropriately modified in accordance with the formation of various forms of POLO structures.
  • the solar cell element 1 may be changed to a solar cell element including a POLO structure on the front surface 1f side, or may be changed to a solar cell element including a POLO structure on each of the front surface 1f side and the back surface 1b side.
  • the POLO structure for example, within the scope of realizing the function of a solar cell, the first region of the crystalline silicon substrate as the first conductivity type may be a p-type semiconductor region or an n-type semiconductor region.
  • the polysilicon layer when the first region is a p-type semiconductor region as the first conductivity type of the crystalline silicon substrate, the polysilicon layer may be a layer containing a p-type dopant as the first conductivity type, or may be a layer containing an n-type dopant as the second conductivity type.
  • the polysilicon layer when the first region is an n-type semiconductor region as the first conductivity type of the crystalline silicon substrate, the polysilicon layer may be a layer containing an n-type dopant as the first conductivity type, or may be a layer containing a p-type dopant as the second conductivity type.
  • the solar cell element may have various forms within the scope of the POLO structure including a first region that is a region of a semiconductor of a first conductivity type in a crystalline silicon substrate, an oxide film located inside the substrate and located along the surface of the substrate or on the surface of the substrate and in contact with the first region, and a polysilicon layer located on the oxide film and containing a dopant of the first conductivity type or the second conductivity type.
  • the solar cell element may have various forms within the scope of the POLO structure including a substrate having a first region that is a region of a semiconductor of a first conductivity type, an oxide film in contact with the first region of the substrate, and a polysilicon layer in contact with the surface of the oxide film opposite to the first region and containing a dopant of the first conductivity type or the second conductivity type.
  • the solar cell element may have various forms within the scope of a structure that includes a substrate having a first region that is a region of a semiconductor of a first conductivity type, and a polysilicon layer that is in contact with the substrate and contains a dopant of the first conductivity type or the second conductivity type, and the substrate is located between the first region and the polysilicon layer, and includes an oxide film that is in contact with each of the first region and the polysilicon layer.
  • this solar cell element includes one POLO structure or two POLO structures among the following Structure 1 to Structure 4.
  • a POLO structure in which an n-type first region, an oxide film, and an n-type polysilicon layer are stacked in the order shown. This structure corresponds to a TOPCon structure, which is a type of POLO structure.
  • a POLO structure in which a p-type first region, an oxide film, and a p-type polysilicon layer are stacked in the order shown. This structure corresponds to a TOPCon structure, which is a type of POLO structure.
  • the solar cell element 1 according to the first embodiment is an example of a solar cell element including the structure 1.
  • Fig. 36 is a cross-sectional view showing an example of the configuration of a solar cell element 1A according to the second embodiment.
  • Fig. 37 is a cross-sectional view showing an example of the configuration of a solar cell element 1B according to the third embodiment.
  • Fig. 38 is an enlarged cross-sectional view showing an example of the configuration of a solar cell element 1A according to the second embodiment, a portion XXXVIII of Fig. 36, and an example of the configuration of a solar cell element 1B according to the third embodiment, a portion XXXVIII of Fig. 37.
  • the solar cell element 1A according to the second embodiment includes, for example, an example of a POLO structure according to the above-mentioned structure 2 on the surface (back surface) 1b side of the solar cell element 1A facing the -Z direction.
  • the solar cell element 1A according to the second embodiment has a configuration based on the solar cell element 1 according to the first embodiment, with the silicon substrate 2 being changed to a silicon substrate 2A.
  • the silicon substrate 2A has a first semiconductor region 21A and a second semiconductor region 22A.
  • the second semiconductor region 22A occupies a portion of the silicon substrate 2A that contacts the second electrode 9.
  • the first semiconductor region 21A occupies substantially the entire area of the silicon substrate 2A except for the portion that contacts the second electrode 9.
  • the first semiconductor region 21A and the second semiconductor region 22A are each a region of a p-type semiconductor as a first conductivity type.
  • the concentration of the p-type dopant in the second semiconductor region 22A is higher than the concentration of the p-type dopant in the first semiconductor region 21A.
  • the solar cell element 1A includes a silicon substrate 2A having a first semiconductor region 21A and an n-type polysilicon layer 4. Furthermore, in the second embodiment, the solar cell element 1A may include a silicon oxide film 3 in contact with the first semiconductor region 21A in addition to the silicon substrate 2A, or the silicon substrate 2A may include a silicon oxide film 3 located between the first semiconductor region 21A and the n-type polysilicon layer 4 and in contact with each of the first semiconductor region 21A and the n-type polysilicon layer 4.
  • the first semiconductor region 21A is a first region as a region of a p-type semiconductor, which is a first conductivity type, in the silicon substrate 2A as a substrate.
  • the silicon oxide film 3 may be an oxide film located inside the silicon substrate 2A and along the surface of the silicon substrate 2A or located on the surface of the silicon substrate 2A and in contact with the first semiconductor region 21A.
  • the n-type polysilicon layer 4 is a polysilicon layer that contacts the surface of the silicon oxide film 3 opposite to the first semiconductor region 21A and contains an n-type dopant as the second conductive type.
  • the n-type polysilicon layer 4 is a polysilicon layer that contacts the silicon substrate 2A and contains an n-type dopant as the second conductive type.
  • the solar cell element 1A according to the second embodiment includes a structure in which the first semiconductor region 21A as the p-type first region, the silicon oxide film 3 as the oxide film, and the n-type polysilicon layer 4 as the n-type polysilicon layer are stacked in the order described above, as an example of the POLO structure according to the above structure 2.
  • the solar cell element 1A according to the second embodiment can be manufactured, for example, by a manufacturing method that is based on but slightly modified from the manufacturing method for the solar cell element 1 according to the first embodiment shown in the flow chart of FIG. 3.
  • a p-type silicon substrate is prepared.
  • a crystalline silicon substrate doped with boron or gallium as a p-type dopant can be prepared as the p-type silicon substrate.
  • step S2 of FIG. 3 a p-type silicon substrate is used instead of an n-type silicon substrate.
  • step S3 of FIG. 3 instead of forming the second semiconductor region 22, the second semiconductor region 22A is locally formed.
  • the portion of the p-type silicon substrate other than the second semiconductor region 22A can become the first semiconductor region 21A.
  • a p-type dopant such as boron is locally introduced into a portion located inside the p-type crystalline silicon substrate and along the surface of the substrate, thereby locally forming the second semiconductor region 22A.
  • the local introduction of the p-type dopant can be realized, for example, by locally irradiating a boron glass layer formed by applying a paste-like boron oxide (B 2 O 3 ) to the surface of the p-type silicon substrate with a laser beam.
  • B 2 O 3 paste-like boron oxide
  • the unnecessary boron glass layer may be removed by etching using, for example, hydrofluoric acid.
  • the local introduction of the p-type dopant may also be realized, for example, by the arrangement of a mask and a vapor phase thermal diffusion method using gaseous boron tribromide (BBr 3 ) as a diffusion source.
  • the second semiconductor region 22A may be formed locally by locally introducing aluminum as a p-type dopant into a portion located inside the p-type silicon substrate and along the surface of the p-type silicon substrate.
  • the local introduction of the p-type dopant can be realized, for example, by locally irradiating a laser beam onto a layer containing aluminum (also called an aluminum-containing layer) formed by applying an aluminum paste to the surface of the p-type silicon substrate and drying it. After this process, the unnecessary aluminum-containing layer may be removed by etching using, for example, hydrochloric acid.
  • the aluminum paste for example, a paste containing aluminum powder, an organic vehicle, and a glass frit may be adopted.
  • steps S4 and S5 of FIG. 3 processing is performed in which the silicon substrate 2 and the first semiconductor region 21 are changed to the silicon substrate 2A and the first semiconductor region 21A.
  • an example of a POLO structure according to the above structure 2 in the solar cell element 1A according to the second embodiment can be formed by processing according to the above-mentioned modified steps S4 and S5. More specifically, for example, an example of a POLO structure according to the above structure 2 in the solar cell element 1A according to the second embodiment can be formed by a manufacturing method for the solar cell element 1A having the following steps 1a, 2a, 3a, and 4a.
  • a silicon oxide film 3 is formed as an oxide film in contact with a first semiconductor region 21A located inside a silicon substrate 2A as a crystalline silicon substrate including a first region 21A that is a region of a p-type semiconductor as a first conductivity type, and along the surface of the silicon substrate 2A or on the surface of the silicon substrate 2A.
  • Step 2a An intrinsic crystalline silicon layer 4a is formed on the silicon oxide film 3 as a first layer of intrinsic crystalline silicon.
  • an n-type amorphous silicon layer 4b is formed as a second layer of amorphous silicon having a thickness greater than that of the intrinsic crystalline silicon layer 4a and containing an n-type dopant (e.g., phosphorus) as the second conductivity type.
  • the n-type amorphous silicon layer 4b may be formed, for example, by using the PECVD method.
  • Step 4a A heat treatment is performed to diffuse the n-type dopant (e.g., phosphorus) contained in the n-type amorphous silicon layer 4b toward the intrinsic crystalline silicon layer 4a and the silicon oxide film 3 while promoting the crystallization of the amorphous silicon of the n-type amorphous silicon layer 4b.
  • the n-type polysilicon layer 4 is generated from the intrinsic crystalline silicon layer 4a and the n-type amorphous silicon layer 4b as a polysilicon layer located on the silicon oxide film 3 and containing the n-type dopant (e.g., phosphorus).
  • an n-type polysilicon layer 4 is formed on the silicon oxide film 3 by carrying out steps 2a to 4a described above.
  • step 1a is an example of the first step of the present disclosure.
  • the above step 2a is an example of the second step of the present disclosure.
  • the above step 3a is an example of the third step of the present disclosure.
  • the above step 4a is an example of the fourth step of the present disclosure.
  • the manufacturing method for solar cell element 1A including steps 1a, 2a, 3a, and 4a can reduce the occurrence of blisters and local defects caused by blisters when forming n-type polysilicon layer 4 as a doped polysilicon layer.
  • defects can be reduced in solar cell element 1A having an example of a POLO structure formed using n-type amorphous silicon layer 4b as a doped amorphous silicon layer. From another perspective, defects in solar cell element 1A can be easily reduced.
  • the solar cell element 1A manufactured by the manufacturing method of the solar cell element 1A according to the second embodiment in which the above steps 1a to 4a are performed can be said to be an element having either of the following configurations 5a and 6a.
  • Solar cell element 1A comprises a silicon substrate 2A, a silicon oxide film 3, and an n-type polysilicon layer 4.
  • Silicon substrate 2A has a first semiconductor region 21A as a first region which is a region of p-type semiconductor as a first conductivity type.
  • Silicon oxide film 3 is an oxide film in contact with first semiconductor region 21A.
  • N-type polysilicon layer 4 is in contact with the surface of silicon oxide film 3 opposite to first semiconductor region 21A, and is an n-type polysilicon layer containing an n-type dopant (e.g., phosphorus) as a second conductivity type different from the first conductivity type.
  • an n-type dopant e.g., phosphorus
  • the n-type polysilicon layer 4 is a layer formed from the intrinsic crystalline silicon layer 4a and the n-type amorphous silicon layer 4b by performing a heat treatment on the intrinsic crystalline silicon layer 4a as a first layer of intrinsic crystalline silicon located on the silicon oxide film 3 and the n-type amorphous silicon layer 4b as a second layer of amorphous silicon located on the intrinsic crystalline silicon layer 4a, having a thickness greater than that of the intrinsic crystalline silicon layer 4a, and containing an n-type dopant (e.g., phosphorus).
  • an n-type dopant e.g., phosphorus
  • This heat treatment is a process that progresses the crystallization of the amorphous silicon of the n-type amorphous silicon layer 4b while diffusing the n-type dopant (e.g., phosphorus) contained in the n-type amorphous silicon layer 4b toward the intrinsic crystalline silicon layer 4a and the silicon oxide film 3.
  • n-type dopant e.g., phosphorus
  • Solar cell element 1A comprises a silicon substrate 2A and an n-type polysilicon layer 4.
  • Silicon substrate 2A has a first semiconductor region 21A as a first region which is a region of p-type semiconductor as a first conductivity type.
  • N-type polysilicon layer 4 is in contact with silicon substrate 2A and is an n-type polysilicon layer containing an n-type dopant (e.g., phosphorus) as a second conductivity type different from the first conductivity type.
  • Silicon substrate 2A includes silicon oxide film 3.
  • Silicon oxide film 3 is an oxide film located between first semiconductor region 21A and n-type polysilicon layer 4, and in contact with both first semiconductor region 21A and n-type polysilicon layer 4.
  • the n-type polysilicon layer 4 is a layer formed from the intrinsic crystalline silicon layer 4a and the n-type amorphous silicon layer 4b by performing a heat treatment on the intrinsic crystalline silicon layer 4a as a first layer of intrinsic crystalline silicon located on the silicon oxide film 3 and the n-type amorphous silicon layer 4b as a second layer of amorphous silicon located on the intrinsic crystalline silicon layer 4a, having a thickness greater than that of the intrinsic crystalline silicon layer 4a, and containing an n-type dopant (e.g., phosphorus).
  • an n-type dopant e.g., phosphorus
  • This heat treatment is a process that progresses the crystallization of the amorphous silicon of the n-type amorphous silicon layer 4b while diffusing the n-type dopant (e.g., phosphorus) contained in the n-type amorphous silicon layer 4b toward the intrinsic crystalline silicon layer 4a and the silicon oxide film 3.
  • n-type dopant e.g., phosphorus
  • the solar cell element 1A having any of the above-mentioned configurations 5a and 6a has a configuration suitable for the manufacturing method of the solar cell element 1A that can reduce the occurrence of blisters and local defects caused by blisters when the n-type polysilicon layer 4 is formed as the doped polysilicon layer.
  • the solar cell element 1A having any of the above-mentioned configurations 5a and 6a has a configuration suitable for the manufacturing method of the solar cell element 1A that can reduce the occurrence of blisters and local defects caused by blisters when the n-type polysilicon layer 4 is formed as the doped polysilicon layer by undergoing the formation of the n-type amorphous silicon layer 4b as the doped amorphous silicon layer and the heat treatment for crystallization of the n-type amorphous silicon layer 4b.
  • the solar cell element 1A having any of the above-mentioned configurations 5a and 6a has a configuration suitable for the manufacturing method of the solar cell element 1A that can reduce defects in the solar cell element 1A having an example of a POLO structure formed using a doped amorphous silicon layer. Therefore, by adopting a solar cell element 1A having any one of the above configurations 5a and 6a, defects in the solar cell element 1A having an example of a POLO structure formed using a doped amorphous silicon layer can be reduced. From another perspective, defects in the solar cell element 1A can be easily reduced.
  • the solar cell element 1A manufactured by the manufacturing method of the solar cell element 1A according to the second embodiment can be an element having either of the following configurations 1a and 2a.
  • Solar cell element 1A comprises a silicon substrate 2A, a silicon oxide film 3, and an n-type polysilicon layer 4.
  • Silicon substrate 2A has a first semiconductor region 21A as a first region which is a region of p-type semiconductor as a first conductivity type.
  • Silicon oxide film 3 is an oxide film in contact with first semiconductor region 21A.
  • N-type polysilicon layer 4 is in contact with the surface of silicon oxide film 3 opposite to first semiconductor region 21A and is an n-type polysilicon layer containing phosphorus which is an n-type dopant as a second conductivity type different from the first conductivity type.
  • N-type polysilicon layer 4 includes a region (oxide film side region) 41 as a second region on the side of silicon oxide film 3 which is in contact with silicon oxide film 3.
  • the distribution of the concentration of phosphorus as an n-type dopant in the first thickness direction D1 as the direction from the surface of the n-type polysilicon layer 4 on the opposite side to the silicon substrate 2A toward the silicon substrate 2A has a maximum first peak Pk1 and a second peak Pk2.
  • the second peak Pk2 is present at a position 3 nm or more away from the position showing the first peak Pk1 in the direction from the first semiconductor region 21A through the silicon oxide film 3 toward the oxide film side region 41.
  • Solar cell element 1A includes silicon substrate 2A and n-type polysilicon layer 4.
  • Silicon substrate 2A has first semiconductor region 21A as a first region, which is a region of p-type semiconductor as a first conductivity type.
  • N-type polysilicon layer 4 is an n-type polysilicon layer that is in contact with silicon substrate 2A and contains phosphorus as an n-type dopant as a second conductivity type different from the first conductivity type.
  • Silicon substrate 2A includes silicon oxide film 3.
  • Silicon oxide film 3 is an oxide film that is located between first semiconductor region 21A and n-type polysilicon layer 4 and is in contact with both first semiconductor region 21A and n-type polysilicon layer 4.
  • N-type polysilicon layer 4 includes region 41 (oxide film side region) as a second region on the side of silicon oxide film 3 that is in contact with silicon oxide film 3.
  • region 41 oxide film side region
  • the distribution of the concentration of phosphorus as an n-type dopant in the first thickness direction D1 as the direction from the surface of the n-type polysilicon layer 4 on the opposite side to the silicon substrate 2A toward the silicon substrate 2A has a maximum first peak Pk1 and a second peak Pk2.
  • the second peak Pk2 is present at a position 3 nm or more away from the position showing the first peak Pk1 in the direction from the first semiconductor region 21A through the silicon oxide film 3 toward the oxide film side region 41.
  • the solar cell element 1A having any of the above configurations 1a and 2a can be said to have a configuration suitable for the manufacturing method of the solar cell element 1A that can reduce the occurrence of blisters and local defects caused by blisters when the n-type polysilicon layer 4 as the doped polysilicon layer is formed.
  • the solar cell element 1A having any of the above configurations 1a and 2a can be said to have a configuration suitable for the manufacturing method of the solar cell element 1A that can reduce the occurrence of blisters and local defects caused by blisters when the n-type polysilicon layer 4 as the doped polysilicon layer is formed through the formation of the n-type amorphous silicon layer 4b as the doped amorphous silicon layer and the heat treatment for crystallization of the n-type amorphous silicon layer 4b.
  • the solar cell element 1A having any of the above configurations 1a and 2a can be said to have a configuration suitable for the manufacturing method of the solar cell element 1A that can reduce defects in the solar cell element 1A having an example of a POLO structure formed using a doped amorphous silicon layer. Therefore, by adopting a solar cell element 1A having any one of the above configurations 1a and 2a, defects in the solar cell element 1A having an example of a POLO structure formed using a doped amorphous silicon layer can be reduced. From another perspective, defects in the solar cell element 1A can be easily reduced.
  • the distribution of the concentration of phosphorus as an n-type dopant in the first thickness direction D1 which is the direction from the surface of the n-type polysilicon layer 4 on the side opposite to the silicon substrate 2A toward the silicon substrate 2A, in the region from the oxide film side region 41 of the n-type polysilicon layer 4 through the silicon oxide film 3 to the first semiconductor region 21A may be the result of measurement using, for example, SIMS.
  • the oxide film side region 41 may be the region closest to the silicon oxide film 3 among the N regions.
  • N may be, for example, 2, 3, or any number equal to or greater than 4.
  • the any number equal to or greater than 4 may be 6.
  • the oxide film side region 41 may be a region of the n-type polysilicon layer 4 that is 10 nm or less away from the silicon oxide film 3.
  • the second peak Pk2 may be located at a position 3 nm to 10 nm away from the position showing the first peak Pk1 in the direction from the first semiconductor region 21A toward the oxide film side region 41 via the silicon oxide film 3.
  • the second peak Pk2 may be located at a position 3 nm to 8 nm away from the position showing the first peak Pk1, or may be located at a position 3 nm to 7 nm away from the position showing the first peak Pk1 in the direction from the first semiconductor region 21A toward the oxide film side region 41 via the silicon oxide film 3.
  • the solar cell element 1B according to the third embodiment includes an example of a POLO structure according to the above structure 2 on the surface (back surface) 1b side facing the -Z direction of the solar cell element 1B.
  • the example of the POLO structure according to the above structure 2 on the back surface 1b side of the solar cell element 1B according to the third embodiment has substantially the same configuration as the example of the POLO structure according to the above structure 2 on the back surface 1b side of the solar cell element 1A according to the second embodiment.
  • the example of the POLO structure according to the above structure 2 on the back surface 1b side of the solar cell element 1B according to the third embodiment can be formed by substantially the same method as the example of the POLO structure according to the above structure 2 on the back surface 1b side of the solar cell element 1A according to the second embodiment.
  • the solar cell element 1B of the third embodiment includes an example of a TOPCon structure, which is a type of POLO structure related to the above-mentioned structure 3, on the surface (front surface) 1f side of the solar cell element 1B facing the +Z direction.
  • a TOPCon structure which is a type of POLO structure related to the above-mentioned structure 3, on the surface (front surface) 1f side of the solar cell element 1B facing the +Z direction.
  • the solar cell element 1B according to the third embodiment is based on the solar cell element 1A according to the second embodiment, with the silicon substrate 2A changed to a silicon substrate 2B, and with the addition of a silicon oxide film 3B as an oxide film and a p-type polysilicon layer 10B as a polysilicon layer containing a p-type dopant as a first conductivity type.
  • the silicon substrate 2B is based on the silicon substrate 2A according to the second embodiment, for example, and has a configuration in which the entire area is the first semiconductor region 21A.
  • the silicon substrate 2B may be, for example, a crystalline silicon substrate doped with boron or gallium as a p-type dopant.
  • the silicon oxide film 3B, the p-type polysilicon layer 10B, and the second electrode 9 are stacked in the order described above.
  • the solar cell element 1B when focusing on the TOPCon structure as a kind of POLO structure according to the above-mentioned structure 3 on the front surface 1f side of the solar cell element 1B, the solar cell element 1B includes a silicon substrate 2B having a first semiconductor region 21A and a p-type polysilicon layer 10B. Furthermore, the solar cell element 1B may include a silicon oxide film 3B that is in contact with the first semiconductor region 21A in addition to the silicon substrate 2B, or the silicon substrate 2B may include a silicon oxide film 3B that is located between the first semiconductor region 21A and the p-type polysilicon layer 10B and in contact with each of the first semiconductor region 21A and the p-type polysilicon layer 10B.
  • the first semiconductor region 21A is a first region as a region of a p-type semiconductor that is a first conductivity type in the silicon substrate 2B as a substrate.
  • the silicon oxide film 3B may be an oxide film that is located inside the silicon substrate 2B and located in a portion along the first surface 2f, or may be an oxide film that is located on the first surface 2f as the surface of the silicon substrate 2B.
  • the p-type polysilicon layer 10B is a p-type polysilicon layer that is in contact with the surface of the silicon oxide film 3B opposite to the first semiconductor region 21A and contains a p-type dopant (e.g., boron) as a first conductive type.
  • a p-type dopant e.g., boron
  • the p-type polysilicon layer 10B is a polysilicon layer that is in contact with the silicon substrate 2B and contains a p-type dopant as a first conductive type.
  • the solar cell element 1B according to the third embodiment includes a structure in which the first semiconductor region 21A as a p-type first region, the silicon oxide film 3B as an oxide film, and the p-type polysilicon layer 10B as a p-type polysilicon layer are stacked in the order described above as an example of a TOPCon structure as a type of POLO structure according to the above structure 3.
  • FIG. 39 is a flow chart showing an example of a method for manufacturing a solar cell element 1B according to the third embodiment.
  • the processes of steps S1B to S9B in FIG. 39 are performed in the order shown, thereby manufacturing the solar cell element 1B.
  • a silicon substrate 2B is prepared.
  • a substrate of crystalline silicon doped with boron or gallium as a p-type dopant can be prepared as the p-type silicon substrate.
  • a textured structure is formed on the first surface 2f of the silicon substrate 2B.
  • the textured structure can be formed, for example, by wet or dry etching of the first surface 2f of the silicon substrate 2B.
  • a silicon oxide film is formed on each of the first surface 2f side and the second surface 2b side of the silicon substrate 2B.
  • a silicon oxide film is formed along the entire surface of the first surface 2f and the entire surface of the second surface 2b of the silicon substrate 2B.
  • a silicon oxide film 3 is formed on the second surface 2b side of the silicon substrate 2B, and a silicon oxide film including a portion of the silicon oxide film 3B is formed on the first surface 2f side of the silicon substrate 2B. Therefore, in this step S3B, as a first example of the first process, a process is performed in which the silicon oxide film 3B in contact with the first semiconductor region 21A of the silicon substrate 2B is formed.
  • a process is performed in which the silicon oxide film 3 in contact with the first semiconductor region 21A of the silicon substrate 2B is formed.
  • a silicon oxide film may be formed on the portion located inside the silicon substrate 2B and along the surface of the silicon substrate 2B, or a silicon oxide film may be formed on the surface of the silicon substrate 2B.
  • the silicon oxide film may be formed by one method or a combination of two or more methods selected from the group consisting of a chemical reaction method, a thermal reaction method, a CVD method, an ALD method, a plasma reaction method, a steam oxidation method, and an ozone oxidation method.
  • the thickness of the silicon oxide film may be set to, for example, 3 nm or less, or 2 nm or less.
  • a p-type polysilicon layer 10B is formed on the silicon oxide film 3B as part of the silicon oxide film on the first surface 2f side of the silicon substrate 2B.
  • a p-type polysilicon layer 10B is formed locally on a part of the silicon oxide film on the first surface 2f side of the silicon substrate 2B.
  • the local formation of the p-type polysilicon layer 10B can be achieved, for example, by setting a mask.
  • the processes of steps S41B to S43B are performed in the order listed, so that the p-type polysilicon layer 10B can be formed.
  • step S41B as a first example of the second step, a step of forming an intrinsic crystalline silicon layer as a layer of intrinsic crystalline silicon (also referred to as the first first layer) on the silicon oxide film 3B is performed.
  • an intrinsic crystalline silicon layer is locally formed on a part of the silicon oxide film.
  • the local formation of the intrinsic crystalline silicon layer can be achieved, for example, by setting a mask.
  • the intrinsic amorphous silicon layer is formed, the intrinsic amorphous silicon layer is subjected to a heat treatment to promote the crystallization of the amorphous silicon, thereby forming the intrinsic crystalline silicon layer.
  • the temperature of this heat treatment is set, for example, within the range of 550°C to 1000°C.
  • the thickness of the intrinsic crystalline silicon layer is set, for example, to 1 nm to 50 nm or less.
  • the intrinsic crystalline silicon layer may be formed by stacking two or more films of intrinsic polysilicon.
  • step S42B as a first example of the third step, a step of forming a p-type amorphous silicon layer on the intrinsic crystalline silicon layer is performed.
  • the p-type amorphous silicon layer has a thickness greater than that of the intrinsic crystalline silicon layer and corresponds to a layer of amorphous silicon (also referred to as a first second layer) containing a p-type dopant as a first conductive type.
  • the p-type amorphous silicon layer is formed, for example, by using a PECVD method. For example, boron (B) is applied as the p-type dopant.
  • the p-type amorphous silicon layer can be formed, for example, by a PECVD method using monosilane (SiH 4 ) gas and diborane (B 2 H 6 ) gas as raw material gas.
  • the thickness of the p-type amorphous silicon layer is set to, for example, 20 nm to 200 nm.
  • step S43B as a first example of the fourth step, a step of forming a p-type polysilicon layer 10B by heat treatment is performed.
  • the intrinsic crystalline silicon layer and the p-type amorphous silicon layer stacked on the silicon oxide film 3B are transformed into the p-type polysilicon layer 10B.
  • a heat treatment is performed to promote crystallization of the amorphous silicon of the p-type amorphous silicon layer while diffusing the p-type dopant contained in the p-type amorphous silicon layer toward the intrinsic crystalline silicon layer and the silicon oxide film 3B.
  • a p-type polysilicon layer 10B located on the silicon oxide film 3B and containing a p-type dopant can be generated from the intrinsic crystalline silicon layer and the p-type amorphous silicon layer.
  • the heat treatment temperature may be set, for example, within the range of 550°C to 1000°C, 700°C to 1000°C, or 700°C to 900°C.
  • an intrinsic crystalline silicon layer having a thickness smaller than that of the p-type amorphous silicon layer is formed on the silicon oxide film 3B.
  • this intrinsic crystalline silicon layer is formed, even if hydrogen bonded to silicon in the intrinsic amorphous silicon layer is desorbed by heat treatment for promoting crystallization of the intrinsic amorphous silicon layer, hydrogen can be released from the surface of the intrinsic amorphous silicon layer opposite to the silicon oxide film 3B. This can reduce the aggregation of hydrogen gas at the interface between the silicon oxide film 3B and the intrinsic crystalline silicon layer.
  • the thickness of the intrinsic amorphous silicon layer before it is transformed into intrinsic crystalline silicon by heat treatment is small, the increase in stress that may cause the silicon layer to peel off from the silicon oxide film 3B due to the contraction of the silicon layer can be reduced when the intrinsic amorphous silicon layer is transformed into intrinsic crystalline silicon by heat treatment. These factors can increase the adhesion between the silicon oxide film 3B and the intrinsic crystalline silicon layer.
  • step S4B when the p-type polysilicon layer 10B is formed on the silicon oxide film 3B, an intrinsic crystalline silicon layer is formed on the silicon oxide film 3B, and then a p-type amorphous silicon layer is formed on the intrinsic crystalline silicon layer, and then the p-type polysilicon layer 10B is generated from the intrinsic crystalline silicon layer and the p-type amorphous silicon layer by heat treatment.
  • This can reduce the occurrence of blisters at the interface between the silicon oxide film 3B and the p-type polysilicon layer 10B, and can also reduce the occurrence of local defects in the p-type polysilicon layer 10B caused by these blisters.
  • the occurrence of blisters and local defects due to blisters when the p-type polysilicon layer 10B is formed as a doped polysilicon layer by using a PECVD method or the like can be reduced.
  • defects can be reduced in the solar cell element 1B having an example of a TOPCon structure, which is a type of POLO structure formed using a doped amorphous silicon layer. From another perspective, defects in the solar cell element 1B can be easily reduced.
  • the reduction in the area where the TOPCon structure, which is a type of POLO structure according to the above-mentioned structure 3 in which the p-type first semiconductor region 21A, the silicon oxide film 3B, and the p-type polysilicon layer 10B are stacked in this order, exists on the surface of the silicon substrate 2B can be reduced.
  • the decrease in passivation performance due to the TOPCon structure, which is a type of POLO structure can be reduced.
  • the conversion efficiency in the solar cell element 1B can be easily improved.
  • step S5B an etching process is performed on the first surface 2f side of the silicon substrate 2B, and the remaining portion of the silicon oxide film on the first surface 2f side of the silicon substrate 2B is removed, except for the silicon oxide film 3B covered with the p-type polysilicon layer 10B. This can make the silicon oxide film 3B visible.
  • step S6B an n-type polysilicon layer 4 is formed on the silicon oxide film 3.
  • the process of step S5 in the first embodiment is used as a basis, and the silicon substrate 2 and the first semiconductor region 21 are changed to the silicon substrate 2B and the first semiconductor region 21A.
  • the processes of steps S51 to S53 in the first embodiment are used as a basis, and the processes of steps S61B to S63B are performed in which the silicon substrate 2 and the first semiconductor region 21 are changed to the silicon substrate 2B and the first semiconductor region 21A.
  • step S61B as a second example of the second step, a process is performed in which an intrinsic crystalline silicon layer 4a is formed on the silicon oxide film 3 as an intrinsic crystalline silicon layer (also called the second first layer).
  • step S62B as a second example of the third step, a step is performed in which an n-type amorphous silicon layer 4b is formed on the intrinsic crystalline silicon layer 4a as an amorphous silicon layer (also called the second second layer) that has a thickness greater than that of the intrinsic crystalline silicon layer 4a and contains an n-type dopant as a first conductive type dopant.
  • step S63B as a second example of the fourth step, a step is performed in which an n-type polysilicon layer 4 is formed by heat treatment.
  • step S6B for example, as in step S5 of the first embodiment, when the n-type polysilicon layer 4 is formed on the silicon oxide film 3, an intrinsic crystalline silicon layer 4a is formed on the silicon oxide film 3, and an n-type amorphous silicon layer 4b is further formed on the intrinsic crystalline silicon layer 4a, and then the n-type polysilicon layer 4 is generated from the intrinsic crystalline silicon layer 4a and the n-type amorphous silicon layer 4b by heat treatment.
  • This can reduce the occurrence of blisters at the interface between the silicon oxide film 3 and the n-type polysilicon layer 4, and can reduce the occurrence of local defects in the n-type polysilicon layer 4 caused by the blisters.
  • the n-type polysilicon layer 4 is formed as a doped polysilicon layer using a PECVD method or the like, the occurrence of blisters and the occurrence of local defects caused by blisters can be reduced.
  • defects can be reduced in the solar cell element 1B having an example of the POLO structure according to the above structure 2 formed using the doped amorphous silicon layer. From another perspective, defects in the solar cell element 1B can be easily reduced.
  • a passivation film 7 is formed on the first surface 2f side of the silicon substrate 2B.
  • the passivation film 7 is formed over the entire surface of the first surface 2f side of the silicon substrate 2B.
  • an aluminum oxide layer may be formed as the passivation film 7 by the ALD method, or a silicon oxide layer may be formed as the passivation film 7 by the PECVD method.
  • an anti-reflection film is formed on each of the first surface 2f and the second surface 2b of the silicon substrate 2B.
  • a first anti-reflection film 5 is formed over the entire surface of the n-type polysilicon layer 4 opposite the silicon substrate 2B
  • a second anti-reflection film 8 is formed over the entire surface of the passivation film 7 opposite the silicon substrate 2B.
  • a silicon nitride layer may be formed as the anti-reflection film by the PECVD method.
  • step S9B electrodes are formed on the first surface 2f side and the second surface 2b side of the silicon substrate 2B.
  • a first electrode 6 is formed on the second surface 2b side of the silicon substrate 2B
  • a second electrode 9 is formed on the first surface 2f side of the silicon substrate 2.
  • a first metal paste is applied to the first anti-reflection film 5 by a screen printing method or the like, and the first metal paste is fired to form the first electrode 6.
  • a second metal paste is applied to the second anti-reflection film 8 by a screen printing method or the like, and the second metal paste is fired to form the second electrode 9.
  • the first metal paste contains a metal powder, an organic vehicle, and a glass frit
  • the glass frit of the first metal paste melts and causes firing penetration of the first anti-reflection film 5.
  • the first electrode 6 penetrates the first anti-reflection film 5 and is connected to the n-type polysilicon layer 4.
  • the second metal paste contains a metal powder, an organic vehicle, and a glass frit
  • the glass frit of the second metal paste melts, causing firing penetration of the second anti-reflection film 8 and the passivation film 7.
  • the second electrode 9 penetrates the second anti-reflection film 8 and the passivation film 7 and is connected to the p-type polysilicon layer 10B.
  • solar cell element 1B having the configuration shown in Figure 37 can be manufactured.
  • an example of a TOPCon structure which is a type of POLO structure relating to the above structure 3 in the solar cell element 1B according to the third embodiment, can be formed by processing in accordance with steps S3B and S4B of the flowchart in FIG. 39. More specifically, for example, an example of a TOPCon structure, which is a type of POLO structure relating to the above structure 3 in the solar cell element 1B according to the third embodiment, can be formed by a manufacturing method for the solar cell element 1B having the following steps 1b, 2b, 3b, and 4b.
  • a silicon oxide film including a silicon oxide film 3B as an oxide film in contact with a first semiconductor region 21A is formed on a portion of a silicon substrate 2B that is located inside the silicon substrate 2B as a substrate of crystalline silicon and that is along the surface of the silicon substrate 2B or on the surface of the silicon substrate 2B, the first semiconductor region 21A as a first region being a region of a p-type semiconductor as a first conductivity type.
  • Step 2b An intrinsic crystalline silicon layer is formed on the silicon oxide film 3B as the first layer (first first layer) of intrinsic crystalline silicon.
  • a p-type amorphous silicon layer is formed on the intrinsic crystalline silicon layer as a second layer (first second layer) of amorphous silicon having a thickness greater than that of the intrinsic crystalline silicon layer and containing a p-type dopant (e.g., boron) as the first conductivity type.
  • the p-type amorphous silicon layer may be formed, for example, by using a PECVD method.
  • Step 4b A heat treatment is performed to diffuse the p-type dopant (e.g., boron) contained in the p-type amorphous silicon layer toward the intrinsic crystalline silicon layer and silicon oxide film 3B while promoting the crystallization of the amorphous silicon of the p-type amorphous silicon layer.
  • a p-type polysilicon layer 10B is generated from the intrinsic crystalline silicon layer and the p-type amorphous silicon layer as a polysilicon layer located on the silicon oxide film 3B and containing a p-type dopant (e.g., boron).
  • step 1b is an example of the first step of the present disclosure.
  • the above step 2b is an example of the second step of the present disclosure.
  • the above step 3b is an example of the third step of the present disclosure.
  • the above step 4b is an example of the fourth step of the present disclosure.
  • the intrinsic crystalline silicon layer is formed on the silicon oxide film 3B, so that the adhesion between the silicon oxide film 3B and the intrinsic crystalline silicon layer can be improved. Then, after the p-type amorphous silicon layer is formed on the intrinsic crystalline silicon layer, when the intrinsic crystalline silicon layer and the p-type amorphous silicon layer are transformed into the p-type polysilicon layer 10B as a doped polysilicon layer by heat treatment, the adhesion of the interface between the silicon oxide film 3B and the p-type polysilicon layer 10B can be ensured.
  • defects can be reduced in the solar cell element 1B having an example of a TOPCon structure, which is a type of POLO structure formed using a doped amorphous silicon layer. From another perspective, defects in the solar cell element 1B can be easily reduced.
  • the solar cell element 1B manufactured by the manufacturing method of the solar cell element 1B according to the third embodiment in which the above steps 1b to 4b are performed can be said to be an element having either of the following configurations 5b and 6b.
  • Solar cell element 1B comprises silicon substrate 2B, silicon oxide film 3B, and p-type polysilicon layer 10B.
  • Silicon substrate 2B has first semiconductor region 21A as a first region which is a region of p-type semiconductor as a first conductivity type.
  • Silicon oxide film 3B is an oxide film in contact with first semiconductor region 21A.
  • P-type polysilicon layer 10B is in contact with the surface of silicon oxide film 3B opposite first semiconductor region 21A and is a p-type polysilicon layer containing a p-type dopant (e.g., boron) as a first conductivity type.
  • a p-type dopant e.g., boron
  • the p-type polysilicon layer 10B is a layer formed from the intrinsic crystalline silicon layer and the p-type amorphous silicon layer by performing a heat treatment on the intrinsic crystalline silicon layer as the first layer of intrinsic crystalline silicon located on the silicon oxide film 3B and the p-type amorphous silicon layer as the second layer of amorphous silicon located on the intrinsic crystalline silicon layer, having a thickness greater than that of the intrinsic crystalline silicon layer, and containing a p-type dopant (e.g., boron).
  • a p-type dopant e.g., boron
  • This heat treatment is a process that progresses the crystallization of the amorphous silicon of the p-type amorphous silicon layer while diffusing the p-type dopant (e.g., boron) contained in the p-type amorphous silicon layer toward the intrinsic crystalline silicon layer and the silicon oxide film 3B.
  • the p-type dopant e.g., boron
  • Solar cell element 1B comprises a silicon substrate 2B and a p-type polysilicon layer 10B.
  • Silicon substrate 2B has a first semiconductor region 21A as a first region which is a region of p-type semiconductor as a first conductivity type.
  • the p-type polysilicon layer 10B is in contact with silicon substrate 2B and is a p-type polysilicon layer containing a p-type dopant (e.g., boron).
  • Silicon substrate 2B includes a silicon oxide film 3B.
  • Silicon oxide film 3B is an oxide film located between first semiconductor region 21A and p-type polysilicon layer 10B and in contact with both first semiconductor region 21A and p-type polysilicon layer 10B.
  • the p-type polysilicon layer 10B is a layer formed from the intrinsic crystalline silicon layer and the p-type amorphous silicon layer by performing a heat treatment on the intrinsic crystalline silicon layer as the first layer of intrinsic crystalline silicon located on the silicon oxide film 3B and the p-type amorphous silicon layer as the second layer of amorphous silicon located on the intrinsic crystalline silicon layer, having a thickness greater than that of the intrinsic crystalline silicon layer, and containing a p-type dopant (e.g., boron).
  • a p-type dopant e.g., boron
  • This heat treatment is a process that progresses the crystallization of the amorphous silicon of the p-type amorphous silicon layer while diffusing the p-type dopant (e.g., boron) contained in the p-type amorphous silicon layer toward the intrinsic crystalline silicon layer and the silicon oxide film 3B.
  • the p-type dopant e.g., boron
  • the solar cell element 1B having any of the above-mentioned configurations 5b and 6b has a configuration suitable for the manufacturing method of the solar cell element 1B that can reduce the occurrence of blisters and the occurrence of local defects caused by blisters when the p-type polysilicon layer 10B is formed as the doped polysilicon layer.
  • the solar cell element 1B having any of the above-mentioned configurations 5b and 6b has a configuration suitable for the manufacturing method of the solar cell element 1B that can reduce the occurrence of blisters and the occurrence of local defects caused by blisters when the p-type polysilicon layer 10B is formed as the doped polysilicon layer by undergoing the formation of the p-type amorphous silicon layer as the doped amorphous silicon layer and the heat treatment for crystallization of the p-type amorphous silicon layer.
  • the solar cell element 1B having any of the above-mentioned configurations 5b and 6b has a configuration suitable for the manufacturing method of the solar cell element 1B that can reduce defects in the solar cell element 1B having an example of a TOPCon structure, which is a type of POLO structure formed using a doped amorphous silicon layer. Therefore, by adopting a solar cell element 1B having any one of the above configurations 5b and 6b, defects in the solar cell element 1B having an example of a TOPCon structure, which is a type of POLO structure formed using a doped amorphous silicon layer, can be reduced. From another perspective, defects in the solar cell element 1B can be easily reduced.
  • an intrinsic crystalline silicon layer is formed on a silicon oxide film, and an n-type amorphous silicon layer is further formed on the intrinsic crystalline silicon layer, and then an n-type polysilicon layer 4 is generated from the intrinsic crystalline silicon layer and the n-type amorphous silicon layer by heat treatment.
  • an intrinsic crystalline silicon layer is formed on a silicon oxide film, and an n-type amorphous silicon layer is further formed on the intrinsic crystalline silicon layer, and then an n-type polysilicon layer 4 is generated from the intrinsic crystalline silicon layer and the n-type amorphous silicon layer by heat treatment.
  • a TOPCon structure which is a type of POLO structure according to the above-mentioned structure 3
  • an intrinsic crystalline silicon layer is formed on a silicon oxide film, and a p-type amorphous silicon layer is further formed on the intrinsic crystalline silicon layer, and then a p-type polysilicon layer 10B is generated from the intrinsic crystalline silicon layer and the p-type amorphous silicon layer by heat treatment.
  • the method for forming an example of a TOPCon structure which is a type of POLO structure relating to structure 1 in the first embodiment
  • the method for forming an example of a TOPCon structure which is a type of POLO structure relating to structure 3 in the third embodiment are methods based on substantially the same technical concept, except for a slight difference in the conductivity type of the dopant between n-type and p-type.
  • the distribution of p-type dopant concentration in the TOPCon structure which is a type of POLO structure according to the above structure 3 of the solar cell element 1B manufactured by the manufacturing method for the solar cell element 1B according to the third embodiment having the above steps 1b to 4b
  • the distribution of n-type dopant concentration in the TOPCon structure which is a type of POLO structure according to the above structure 1 of the solar cell element 1 manufactured by the manufacturing method for the solar cell element 1 according to the first embodiment having the above steps 1 to 4
  • the distribution of p-type dopant concentration in the TOPCon structure which is a type of POLO structure according to the above structure 3 of the solar cell element 1B manufactured by the manufacturing method for the solar cell element 1B according to the third embodiment having the above steps 1b to 4b
  • the distribution of n-type dopant concentration in the POLO structure according to the above structure 2 of the solar cell element 1A manufactured by the manufacturing method for the solar cell element 1A according to the second embodiment having the above steps 1a to 4a may show the same tendency due to the same mechanism.
  • the solar cell element 1B manufactured by the manufacturing method of the solar cell element 1B according to the third embodiment can be an element having either of the following configurations 1b and 2b.
  • Solar cell element 1B comprises silicon substrate 2B, silicon oxide film 3B, and p-type polysilicon layer 10B.
  • Silicon substrate 2B has first semiconductor region 21A as a first region which is a region of p-type semiconductor as a first conductivity type.
  • Silicon oxide film 3B is an oxide film in contact with first semiconductor region 21A.
  • P-type polysilicon layer 10B is in contact with the surface of silicon oxide film 3B opposite to first semiconductor region 21A and is a p-type polysilicon layer containing a p-type dopant (e.g., boron) as a first conductivity type.
  • a p-type dopant e.g., boron
  • the p-type polysilicon layer includes region 10B1 (oxide film side region) as a second region on the side of silicon oxide film 3B in contact with silicon oxide film 3B.
  • region 10B1 oxide film side region
  • the distribution of the concentration of the p-type dopant (e.g., boron) in the second thickness direction from the surface of the p-type polysilicon layer 10B opposite the silicon substrate 2B toward the silicon substrate 2B has a maximum first peak and a second peak.
  • the second peak is located at a position 3 nm or more away from the position showing the first peak in the direction from the first semiconductor region 21A through the silicon oxide film 3B toward the oxide film side region 10B1.
  • Solar cell element 1B includes silicon substrate 2B and p-type polysilicon layer 10B.
  • Silicon substrate 2B has first semiconductor region 21A as a first region, which is a region of p-type semiconductor as a first conductivity type.
  • P-type polysilicon layer 10B is a p-type polysilicon layer that is in contact with silicon substrate 2B and contains p-type dopant (e.g., boron).
  • Silicon substrate 2B includes silicon oxide film 3B.
  • Silicon oxide film 3B is an oxide film that is located between first semiconductor region 21A and p-type polysilicon layer 10B and is in contact with both first semiconductor region 21A and p-type polysilicon layer 10B.
  • P-type polysilicon layer 10B includes region (oxide film side region) 10B1 as a second region on the side of silicon oxide film 3B that is in contact with silicon oxide film 3B.
  • the distribution of the concentration of the p-type dopant (e.g., boron) in the second thickness direction from the surface of the p-type polysilicon layer 10B opposite the silicon substrate 2B toward the silicon substrate 2B has a maximum first peak and a second peak.
  • the second peak is located at a position 3 nm or more away from the position showing the first peak in the direction from the first semiconductor region 21A through the silicon oxide film 3B toward the oxide film side region 10B1.
  • the solar cell element 1B having any of the above-mentioned configurations 1b and 2b can be said to have a configuration suitable for the manufacturing method of the solar cell element 1B that can reduce the occurrence of blisters and local defects caused by blisters when the p-type polysilicon layer 10B is formed as a doped polysilicon layer.
  • the solar cell element 1B having any of the above-mentioned configurations 1b and 2b can be said to have a configuration suitable for the manufacturing method of the solar cell element 1B that can reduce the occurrence of blisters and local defects caused by blisters when the p-type polysilicon layer 10B is formed as a doped polysilicon layer by undergoing the formation of a p-type amorphous silicon layer as a doped amorphous silicon layer and the heat treatment for crystallization of the p-type amorphous silicon layer.
  • the solar cell element 1B having any of the above-mentioned configurations 1b and 2b can be said to have a configuration suitable for the manufacturing method of the solar cell element 1B that can reduce defects in the solar cell element 1B having an example of a TOPCon structure, which is a type of POLO structure formed using a doped amorphous silicon layer. Therefore, by adopting a solar cell element 1B having any one of the above configurations 1b and 2b, defects in the solar cell element 1B having an example of a TOPCon structure, which is a type of POLO structure formed using a doped amorphous silicon layer, can be reduced. From another perspective, defects in the solar cell element 1B can be easily reduced.
  • the distribution of the concentration of the p-type dopant (e.g., boron) in the second thickness direction from the surface of the p-type polysilicon layer 10B opposite the silicon substrate 2B toward the silicon substrate 2B in the region from the oxide film side region 10B1 of the p-type polysilicon layer 10B through the silicon oxide film 3B to the first semiconductor region 21A may be the result of measurement using, for example, SIMS.
  • the second direction is the direction from the surface of the p-type polysilicon layer opposite the substrate toward the substrate. This second direction may be a direction along the thickness directions of the p-type polysilicon layer, the silicon oxide film, and the substrate.
  • the specific p-type dopant may mean one specific type of element among p-type dopants. For example, boron is used as this one specific type of element.
  • a method for recognizing the characteristics of the distribution of the concentration of a specific p-type dopant (e.g., boron) in the second direction of a sample, taking into account noise components may be based on an example of the first recognition method described above, and may apply a method in which the specific n-type dopant is changed to a specific p-type dopant (also referred to as the 1A recognition method).
  • a specific p-type dopant e.g., boron
  • the four processes of [1A] calculation of an index related to the noise components, [2A] calculation of an approximation line, [3A] calculation of a judgment line, and [4A] peak recognition are performed in the order described, thereby recognizing the characteristics of the distribution of the concentration of a specific p-type dopant in the second direction of a sample.
  • SIMS can obtain data on the distribution of the concentration of a specific p-type dopant (e.g., boron) in a sample in the second direction while digging into the surface of the sample in the second direction. More specifically, SIMS can obtain data on the distribution of the concentration of a specific p-type dopant in a sample in the second direction by sequentially measuring the concentration of a specific p-type dopant at multiple discrete positions in the second direction of the sample. These discrete positions are positions (measurement positions) in the second direction of the sample where the concentration of a specific p-type dopant is measured, from the first to the Mth (M is a natural number).
  • M is a natural number
  • the discrete positions are the first measurement position, the second measurement position, the third measurement position, ..., the Mth measurement position in the second direction of the sample. Therefore, the concentration of a specific p-type dopant measured in sequence from the first to the Mth measurement positions in the second direction of one sample using SIMS is the concentration of the specific p-type dopant measured in sequence from the first to the Mth positions in one sample.
  • data showing the distribution of the concentration of a specific p-type dopant in the second direction of one sample obtained using SIMS is composed of data on the concentration of a specific p-type dopant measured in sequence from the first to the Mth positions in the second direction of one sample.
  • the concentration of the specific p-type dopant measured at the nth position (n is an integer) and the concentration of the specific p-type dopant measured at the n+1th position among the M concentrations of specific p-type dopants measured in sequence from the first to the Mth positions in the second direction of one sample are considered to be the concentrations of two specific p-type dopants adjacent to each other in the second direction.
  • ⁇ D2(n) as the ⁇ p-type dopant concentration is calculated by the formula (1A).
  • ⁇ D2(n)
  • D2(n) indicates the concentration of the specific p-type dopant measured at the nth measurement in the distribution of the concentration of the specific p-type dopant in the second direction of the sample.
  • D2(n+1) indicates the concentration of the specific p-type dopant measured at the n+1th measurement in the distribution of the concentration of the specific p-type dopant in the second direction of the sample.
  • the absolute value of the difference between the concentration of the specific p-type dopant measured at the n+1th measurement and the concentration of the specific p-type dopant measured at the nth measurement is calculated as the ⁇ p-type dopant concentration related to the concentration of the specific p-type dopant measured at the nth measurement.
  • ⁇ B(n) as the ⁇ boron concentration is calculated by formula (2A).
  • B(n) indicates the nth measured boron concentration in the distribution of boron concentration in the second direction of the sample.
  • B(n+1) indicates the n+1th measured boron concentration in the distribution of boron concentration in the second direction of the sample.
  • the absolute value of the difference between the n+1th measured boron concentration and the nth measured boron concentration in the distribution of boron concentration in the second direction of the sample is calculated as the ⁇ boron concentration for the nth measured boron concentration.
  • the portion where the ⁇ p-type dopant concentration is finely wavy near zero (0) is estimated to indicate the variation in the measured value corresponding to the noise component in the distribution of the concentration of the specific p-type dopant (e.g., boron) in the second direction of the sample.
  • a base region (base region) in which the concentration of the specific p-type dopant in the second direction is estimated to be substantially unchanged is set in a part of the region in the second direction where the ⁇ p-type dopant concentration is finely wavy near zero (0).
  • the maximum peak (first peak) is used as a reference, and the region from the position of the first distance to the position of the second distance is set as the base region.
  • the first distance may be set to, for example, 8 nm to 10 nm.
  • the second distance may be set to, for example, 15 nm to 25 nm.
  • the second distance may be set according to, for example, the thickness of the p-type polysilicon layer.
  • the second distance may be set to half the thickness of the p-type polysilicon layer or less.
  • the second distance may be set to 30 nm or less.
  • the second distance may be set to 15 nm or less.
  • the standard deviation ⁇ of the ⁇ p-type dopant concentration in the base region is calculated as an index (first A index) related to the noise component of the distribution of the concentration of a specific p-type dopant (e.g., boron) in the second direction of the sample.
  • first A index related to the noise component of the distribution of the concentration of a specific p-type dopant (e.g., boron) in the second direction of the sample.
  • a line of a function (approximation function) that approximates the distribution of the concentration of a specific p-type dopant (e.g., boron) in the second direction of the sample in the base region is calculated.
  • the line of the approximation function is calculated as a line (approximation line) that is extended in the second direction of the sample in a form that exists not only in the base region but also in regions other than the base region.
  • a region from the base region in the second direction of the sample to a position showing the first peak may be adopted.
  • the region including the base region and the region other than the base region in the second direction of the sample for example, a region from a region on the silicon oxide film side of the p-type polysilicon layer in the second direction through the silicon oxide film to a semiconductor region of the substrate may be adopted.
  • the line of the approximation function a straight line of a linear function obtained by the least squares method may be adopted.
  • the approximation line is a straight line of a linear function.
  • a curve of a quadratic function obtained by the least squares method may be adopted.
  • the approximation line is a curve of a quadratic function.
  • the above-mentioned approximation line that approximates the distribution of the concentration of a specific p-type dopant (e.g., boron) in the second direction of the sample in the base region is used as a reference, and a value m times the standard deviation ⁇ (m is a value between 3 and 4) as the first A index is added to each concentration of the specific p-type dopant in the approximation line to calculate a line (also called a judgment line) in which the approximation line is shifted.
  • the approximation line is a straight line of a linear function
  • the judgment line is a straight line of a linear function.
  • the approximation line is a curve of a quadratic function
  • the judgment line is a curve of a quadratic function.
  • a significant peak of the concentration of the specific p-type dopant may be recognized for a portion where the concentration of the specific p-type dopant continues to exceed the judgment line in a range of a predetermined length or more in the second direction.
  • the predetermined length may be set to, for example, 1 nm, 1.5 nm, or 2 nm.
  • the oxide film side region 10B1 may be the region closest to the silicon oxide film 3B among the N regions (N is a natural number of 2 or more) when the p-type polysilicon layer 10B is equally divided into N regions in the second thickness direction.
  • N may be, for example, 2, 3, or any number of 4 or more.
  • the any number of 4 or more may be 6.
  • the oxide film side region 10B1 may be a region of the p-type polysilicon layer 10B that is 10 nm or less away from the silicon oxide film 3B.
  • the second peak may be present at a position 3 nm to 10 nm away from the position showing the first peak in the direction from the first semiconductor region 21A through the silicon oxide film 3B toward the oxide film side region 10B1.
  • the second peak may be present at a position 3 nm to 8 nm away from the position showing the first peak, or may be present at a position 3 nm to 7 nm away from the position showing the first peak, in the direction from the first semiconductor region 21A through the silicon oxide film 3B toward the oxide film side region 10B1.
  • Fig. 40 is a cross-sectional view that shows an example of the configuration of a solar cell element 1C according to a fourth embodiment.
  • Fig. 41 is a cross-sectional view that shows an example of the configuration of a solar cell element 1D according to a fifth embodiment.
  • the solar cell element 1C according to the fourth embodiment includes, for example, an example of a POLO structure according to the above-mentioned structure 4 on the surface (back surface) 1b side of the solar cell element 1C facing the -Z direction.
  • the solar cell element 1C according to the fourth embodiment is based on the solar cell element 1 according to the first embodiment, with the silicon substrate 2 being changed to a silicon substrate 2C, the n-type polysilicon layer 4 being changed to a p-type polysilicon layer 10C, the passivation film 7 being removed, and a passivation film 7C being added.
  • the silicon substrate 2C has a first semiconductor region 21 and a second semiconductor region 22C.
  • the silicon substrate 2C has a configuration in which the silicon substrate 2 according to the first embodiment is used as a base, and the second semiconductor region 22 is changed to the second semiconductor region 22C.
  • Each of the first semiconductor region 21 and the second semiconductor region 22C is an n-type semiconductor region as a first conductivity type.
  • the concentration of n-type dopants in the second semiconductor region 22C is higher than the concentration of n-type dopants in the first semiconductor region 21.
  • the second anti-reflection film 8 is positioned in a state in which it covers almost the entire surface of the first surface 2f of the silicon substrate 2C, except for the region where the second electrode 9 is located.
  • the second anti-reflection film 8 is in contact with the second semiconductor region 22C of the silicon substrate 2C.
  • the passivation film 7C is positioned on the p-type polysilicon layer 10C. More specifically, the passivation film 7C is located on the surface of the p-type polysilicon layer 10C opposite the silicon substrate 2C.
  • the passivation film 7C may be, for example, an aluminum oxide layer or a silicon oxide layer.
  • the first anti-reflection film 5 is located on the passivation film 7C.
  • the solar cell element 1C includes a silicon substrate 2C having a first semiconductor region 21 and a p-type polysilicon layer 10C.
  • the solar cell element 1C may include a silicon oxide film 3 in contact with the first semiconductor region 21 in addition to the silicon substrate 2C, or the silicon substrate 2C may include a silicon oxide film 3 located between the first semiconductor region 21 and the p-type polysilicon layer 10C and in contact with each of the first semiconductor region 21 and the p-type polysilicon layer 10C.
  • the first semiconductor region 21 is a first region as a region of n-type semiconductor, which is a first conductivity type, in the silicon substrate 2C as a substrate.
  • the silicon oxide film 3 may be an oxide film located inside the silicon substrate 2C and located along the second surface 2b, or may be an oxide film located on the second surface 2b as the surface of the silicon substrate 2C.
  • the p-type polysilicon layer 10C is a p-type polysilicon layer that is in contact with the surface of the silicon oxide film 3 opposite to the first semiconductor region 21 and contains a p-type dopant (e.g., boron) as a second conductivity type different from the first conductivity type.
  • a p-type dopant e.g., boron
  • the p-type polysilicon layer 10C is a polysilicon layer that is in contact with the silicon substrate 2C and contains a p-type dopant as a second conductivity type.
  • the solar cell element 1C according to the fourth embodiment includes a structure in which the first semiconductor region 21 as the n-type first region, the silicon oxide film 3 as the oxide film, and the p-type polysilicon layer 10C as the p-type polysilicon layer are stacked in the order described above, as an example of the POLO structure according to the above structure 4.
  • the solar cell element 1C according to the fourth embodiment can be manufactured, for example, by a manufacturing method that is based on but slightly modified from the manufacturing method for the solar cell element 1 according to the first embodiment shown in the flow chart of FIG. 3.
  • the second semiconductor region 22C is formed.
  • an n-type dopant such as phosphorus is introduced into a portion located inside the n-type silicon substrate 2C and along the first surface 2f, thereby forming the second semiconductor region 22C.
  • the introduction of the n-type dopant can be performed, for example, by using a vapor phase thermal diffusion method in which gaseous phosphorus oxychloride (POCl 3 ) is used as a diffusion source, or a coating thermal diffusion method in which a paste of diphosphorus pentoxide (P 2 O 5 ) is applied to the first surface 2f of the silicon substrate 2C and phosphorus is thermally diffused.
  • a vapor phase thermal diffusion method in which gaseous phosphorus oxychloride (POCl 3 ) is used as a diffusion source
  • a coating thermal diffusion method in which a paste of diphosphorus pentoxide (P 2 O 5 ) is applied to the first surface 2f of the silicon substrate 2C and phosphorus is thermally diffused.
  • POCl 3 gaseous phosphorus oxychloride
  • P 2 O 5 diphosphorus pentoxide
  • the phosphorus glass is removed by etching using an aqueous solution containing hydrofluoric acid or the like.
  • a diffusion mask may be formed in advance, and the diffusion mask may be removed after the second semiconductor region 22C is formed.
  • step S4 in FIG. 3 a process is performed in which the silicon substrate 2 is changed to a silicon substrate 2C.
  • a process is carried out in which a silicon oxide film 3 is formed in contact with the first semiconductor region 21 of the silicon substrate 2C, as an example of a first process.
  • the silicon oxide film 3 may be formed in a portion located inside the silicon substrate 2C and along the surface of the silicon substrate 2C, or the silicon oxide film 3 may be formed on the surface of the silicon substrate 2C.
  • step S5 of FIG. 3 a p-type polysilicon layer 10C is formed on the silicon oxide film 3 in place of the n-type polysilicon layer 4.
  • the processes from step S51 to step S53 in the first embodiment are slightly modified and are performed in the order described here, thereby forming the p-type polysilicon layer 10C.
  • step S51 a step of forming an intrinsic crystalline silicon layer as a layer (first layer) of intrinsic crystalline silicon corresponding to the intrinsic crystalline silicon layer 4a on the silicon oxide film 3 is carried out.
  • the intrinsic crystalline silicon layer is formed on the surface of the silicon oxide film 3 opposite to the first semiconductor region 21.
  • the intrinsic crystalline silicon layer may be, for example, a layer of intrinsic polycrystalline silicon.
  • the intrinsic amorphous silicon layer is subjected to a heat treatment to promote the crystallization of the amorphous silicon, so that the intrinsic crystalline silicon layer can be formed.
  • the temperature of this heat treatment is set, for example, within a range of 550°C to 1000°C.
  • the oxide film on each surface of the second semiconductor region 22C of the silicon substrate 2C formed up to the intrinsic crystalline silicon layer and the intrinsic crystalline silicon layer may be removed with an aqueous solution containing hydrofluoric acid.
  • the thickness of the intrinsic crystalline silicon layer is set to, for example, 1 nm to 50 nm or less.
  • the intrinsic crystalline silicon layer may be formed by stacking two or more films of intrinsic polysilicon.
  • a p-type amorphous silicon layer is formed on the intrinsic crystalline silicon layer instead of the n-type amorphous silicon layer 4b.
  • the p-type amorphous silicon layer has a thickness greater than that of the intrinsic crystalline silicon layer and corresponds to a layer (second layer) of amorphous silicon containing a p-type dopant as a second conductive type.
  • boron or the like is applied as the p-type dopant contained in the p-type amorphous silicon layer.
  • the p-type amorphous silicon layer can be formed by a PECVD method using, for example, monosilane (SiH 4 ) gas and diborane (B 2 H 6 ) gas as raw material gas.
  • the thickness of the p-type amorphous silicon layer is set to, for example, 20 nm to 200 nm.
  • step S53 as an example of the fourth step, a step of forming a p-type polysilicon layer 10C instead of the n-type polysilicon layer 4 by heat treatment is performed.
  • the intrinsic crystalline silicon layer and the p-type amorphous silicon layer stacked on the silicon oxide film 3 are transformed into a p-type polysilicon layer 10C.
  • a heat treatment is performed to promote crystallization of the amorphous silicon of the p-type amorphous silicon layer while diffusing the p-type dopant contained in the p-type amorphous silicon layer toward the intrinsic crystalline silicon layer and the silicon oxide film 3.
  • a p-type polysilicon layer 10C located on the silicon oxide film 3 and containing a p-type dopant can be generated from the intrinsic crystalline silicon layer and the p-type amorphous silicon layer.
  • the heat treatment temperature may be set, for example, within the range of 550°C to 1000°C, 700°C to 1000°C, or 700°C to 900°C.
  • an intrinsic crystalline silicon layer having a thickness smaller than that of the p-type amorphous silicon layer is formed on the silicon oxide film 3.
  • this intrinsic crystalline silicon layer is formed, even if hydrogen bonded to silicon in the intrinsic amorphous silicon layer is desorbed by heat treatment for promoting crystallization of the intrinsic amorphous silicon layer, hydrogen can be released from the surface of the intrinsic amorphous silicon layer opposite to the silicon oxide film 3B. This can reduce the aggregation of hydrogen gas at the interface between the silicon oxide film 3 and the intrinsic crystalline silicon layer.
  • the thickness of the intrinsic amorphous silicon layer before it is transformed into intrinsic crystalline silicon by heat treatment is small, the increase in stress that may cause the silicon layer to peel off from the silicon oxide film 3 due to the contraction of the silicon layer can be reduced when the intrinsic amorphous silicon layer is transformed into intrinsic crystalline silicon by heat treatment. These factors can increase the adhesion between the silicon oxide film 3 and the intrinsic crystalline silicon layer.
  • step S5 when the p-type polysilicon layer 10C is formed on the silicon oxide film 3, an intrinsic crystalline silicon layer is formed on the silicon oxide film 3, and a p-type amorphous silicon layer is further formed on the intrinsic crystalline silicon layer, and then the p-type polysilicon layer 10C is generated from the intrinsic crystalline silicon layer and the p-type amorphous silicon layer by heat treatment.
  • This can reduce the occurrence of blisters at the interface between the silicon oxide film 3 and the p-type polysilicon layer 10C, and can also reduce the occurrence of localized defects in the p-type polysilicon layer 10B caused by these blisters.
  • a passivation film 7C is formed on the second surface 2b side of the silicon substrate 2C.
  • the passivation film 7C is formed over the entire surface of the p-type polysilicon layer 10C formed on the second surface 2b side of the silicon substrate 2C opposite the silicon substrate 2C.
  • an aluminum oxide layer may be formed as the passivation film 7C by the ALD method, or a silicon oxide layer may be formed as the passivation film 7C by the PECVD method.
  • an anti-reflection film is formed on each of the first surface 2f and the second surface 2b of the silicon substrate 2C.
  • a first anti-reflection film 5 is formed over the entire surface of the passivation film 7C opposite the silicon substrate 2C, rather than on the n-type polysilicon layer 4, and a second anti-reflection film 8 is formed over the entire surface of the second semiconductor region 22C.
  • a silicon nitride layer may be formed as the anti-reflection film by the PECVD method.
  • a process is performed in which the silicon substrate 2 is changed to a silicon substrate 2C.
  • electrodes are formed on the first surface 2f side and the second surface 2b side of the silicon substrate 2C.
  • a first electrode 6 is formed on the second surface 2b side of the silicon substrate 2C, and a second electrode 9 is formed on the first surface 2f side of the silicon substrate 2C.
  • a first metal paste is applied to the first anti-reflection film 5 by a screen printing method or the like, and the first metal paste is fired to form the first electrode 6.
  • a second metal paste is applied to the second anti-reflection film 8 by a screen printing method or the like, and the second electrode 9 is formed by firing the second metal paste.
  • the first metal paste contains a metal powder, an organic vehicle, and a glass frit
  • the glass frit of the first metal paste melts and causes firing penetration of the first anti-reflection film 5 and the passivation film 7C.
  • the first electrode 6 penetrates the first anti-reflection film 5 and the passivation film 7C and is connected to the p-type polysilicon layer 10C.
  • the second metal paste contains metal powder, an organic vehicle, and glass frit
  • the glass frit of the second metal paste melts and causes firing penetration of the second anti-reflection film 8.
  • the second electrode 9 penetrates the second anti-reflection film 8 and is connected to the second semiconductor region 22C.
  • solar cell element 1C having the configuration shown in Figure 40 can be manufactured.
  • an example of a POLO structure according to structure 4 in solar cell element 1C according to the fourth embodiment can be formed by processing according to steps S4 and S5 after the above-described changes. More specifically, for example, an example of a POLO structure according to structure 4 in solar cell element 1C according to the fourth embodiment can be formed by a manufacturing method for solar cell element 1C having the following steps 1c, 2c, 3c, and 4c.
  • a silicon oxide film 3 is formed as an oxide film in contact with a first semiconductor region 21 located inside a silicon substrate 2C as a crystalline silicon substrate including a first region that is an n-type semiconductor region as a first conductivity type and along the surface of the silicon substrate 2C or on the surface of the silicon substrate 2C.
  • Step 2c An intrinsic crystalline silicon layer is formed on the silicon oxide film 3 as a first layer of intrinsic crystalline silicon.
  • a p-type amorphous silicon layer is formed on the intrinsic crystalline silicon layer as a second layer of amorphous silicon having a thickness greater than that of the intrinsic crystalline silicon layer and containing a p-type dopant (e.g., boron) as a second conductivity type different from the first conductivity type.
  • the p-type amorphous silicon layer may be formed, for example, by using a PECVD method.
  • Step 4c A heat treatment is performed to diffuse the p-type dopant (e.g., boron) contained in the p-type amorphous silicon layer toward the intrinsic crystalline silicon layer and the silicon oxide film 3 while promoting the crystallization of the amorphous silicon of the p-type amorphous silicon layer.
  • a p-type polysilicon layer 10C is generated from the intrinsic crystalline silicon layer and the p-type amorphous silicon layer as a polysilicon layer located on the silicon oxide film 3 and containing a p-type dopant (e.g., boron).
  • step 1c is an example of the first step of the present disclosure.
  • the above step 2c is an example of the second step of the present disclosure.
  • the above step 3c is an example of the third step of the present disclosure.
  • the above step 4c is an example of the fourth step of the present disclosure.
  • the intrinsic crystalline silicon layer is formed on the silicon oxide film 3, so that the adhesion between the silicon oxide film 3 and the intrinsic crystalline silicon layer can be improved.
  • the p-type amorphous silicon layer is formed on the intrinsic crystalline silicon layer, when the intrinsic crystalline silicon layer and the p-type amorphous silicon layer are transformed into the p-type polysilicon layer 10C as a doped polysilicon layer by heat treatment, the adhesion of the interface between the silicon oxide film 3 and the p-type polysilicon layer 10B can be ensured.
  • the solar cell element 1C manufactured by the manufacturing method of the solar cell element 1C according to the fourth embodiment in which the above steps 1c to 4c are performed can be said to be an element having either of the following configurations 5c and 6c.
  • Solar cell element 1B comprises a silicon substrate 2C, a silicon oxide film 3, and a p-type polysilicon layer 10C.
  • Silicon substrate 2C has a first semiconductor region 21 as a first region which is a region of n-type semiconductor as a first conductivity type.
  • Silicon oxide film 3 is an oxide film in contact with first semiconductor region 21.
  • P-type polysilicon layer 10C is in contact with the surface of silicon oxide film 3 opposite to first semiconductor region 21 and is a p-type polysilicon layer containing a p-type dopant (e.g., boron) as a second conductivity type different from the first conductivity type.
  • a p-type dopant e.g., boron
  • the p-type polysilicon layer 10C is a layer formed from the intrinsic crystalline silicon layer and the p-type amorphous silicon layer by performing a heat treatment on the intrinsic crystalline silicon layer as the first layer of intrinsic crystalline silicon located on the silicon oxide film 3 and the p-type amorphous silicon layer as the second layer of amorphous silicon located on the intrinsic crystalline silicon layer, having a thickness greater than that of the intrinsic crystalline silicon layer, and containing a p-type dopant (e.g., boron).
  • a p-type dopant e.g., boron
  • This heat treatment is a process that progresses the crystallization of the amorphous silicon of the p-type amorphous silicon layer while diffusing the p-type dopant (e.g., boron) contained in the p-type amorphous silicon layer toward the intrinsic crystalline silicon layer and the silicon oxide film 3.
  • the p-type dopant e.g., boron
  • Solar cell element 1C comprises a silicon substrate 2C and a p-type polysilicon layer 10C.
  • Silicon substrate 2C has a first semiconductor region 21 as a first region which is a region of n-type semiconductor as a first conductivity type.
  • P-type polysilicon layer 10C is in contact with silicon substrate 2C and is a p-type polysilicon layer containing a p-type dopant (e.g., boron) as a second conductivity type different from the first conductivity type.
  • Silicon substrate 2C includes silicon oxide film 3.
  • Silicon oxide film 3 is an oxide film located between first semiconductor region 21 and p-type polysilicon layer 10C and in contact with both first semiconductor region 21 and p-type polysilicon layer 10C.
  • the p-type polysilicon layer 10C is a layer formed from the intrinsic crystalline silicon layer and the p-type amorphous silicon layer by performing a heat treatment on the intrinsic crystalline silicon layer as the first layer of intrinsic crystalline silicon located on the silicon oxide film 3 and the p-type amorphous silicon layer as the second layer of amorphous silicon located on the intrinsic crystalline silicon layer, having a thickness greater than that of the intrinsic crystalline silicon layer, and containing a p-type dopant (e.g., boron).
  • a p-type dopant e.g., boron
  • This heat treatment is a process that progresses the crystallization of the amorphous silicon of the p-type amorphous silicon layer while diffusing the p-type dopant (e.g., boron) contained in the p-type amorphous silicon layer toward the intrinsic crystalline silicon layer and the silicon oxide film 3.
  • the p-type dopant e.g., boron
  • the solar cell element 1C having any of the above-mentioned configurations 5c and 6c has a configuration suitable for the manufacturing method of the solar cell element 1C that can reduce the occurrence of blisters and local defects caused by blisters when the p-type polysilicon layer 10C is formed as the doped polysilicon layer.
  • the solar cell element 1C having any of the above-mentioned configurations 5c and 6c has a configuration suitable for the manufacturing method of the solar cell element 1C that can reduce the occurrence of blisters and local defects caused by blisters when the p-type polysilicon layer 10C is formed as the doped polysilicon layer by undergoing the formation of the p-type amorphous silicon layer as the doped amorphous silicon layer and the heat treatment for crystallization of the p-type amorphous silicon layer.
  • the solar cell element 1C having any of the above-mentioned configurations 5c and 6c has a configuration suitable for the manufacturing method of the solar cell element 1C that can reduce defects in the solar cell element 1C having an example of a POLO structure formed using a doped amorphous silicon layer. Therefore, by adopting a solar cell element 1C having any one of the above configurations 5c and 6c, defects in the solar cell element 1C having an example of a POLO structure formed using a doped amorphous silicon layer can be reduced. From another perspective, defects in the solar cell element 1C can be easily reduced.
  • an intrinsic crystalline silicon layer is formed on a silicon oxide film along the surface of the p-type first semiconductor region 21A in the silicon substrate 2B, and a p-type amorphous silicon layer is further formed on the intrinsic crystalline silicon layer.
  • a p-type polysilicon layer 10B is generated from the intrinsic crystalline silicon layer and the p-type amorphous silicon layer by heat treatment.
  • an intrinsic crystalline silicon layer is formed on the silicon oxide film along the surface of the n-type first semiconductor region 21 in the silicon substrate 2C, and a p-type amorphous silicon layer is further formed on the intrinsic crystalline silicon layer, and then a p-type polysilicon layer 10C is generated from the intrinsic crystalline silicon layer and the p-type amorphous silicon layer by heat treatment.
  • the method for forming an example of a TOPCon structure which is a type of POLO structure related to structure 3 in the third embodiment
  • the method for forming an example of a POLO structure related to structure 4 in the fourth embodiment are methods based on substantially the same technical concept, except for a slight difference between the conductivity type of the silicon substrate, that is, n-type and p-type.
  • the solar cell element 1C manufactured by the manufacturing method of the solar cell element 1C according to the fourth embodiment can be an element having either of the following configurations 1c and 2c.
  • Solar cell element 1B comprises silicon substrate 2C, silicon oxide film 3, and p-type polysilicon layer 10C.
  • Silicon substrate 2C has first semiconductor region 21 as a first region which is a region of n-type semiconductor as a first conductivity type.
  • Silicon oxide film 3 is an oxide film in contact with first semiconductor region 21.
  • P-type polysilicon layer 10C is in contact with the surface of silicon oxide film 3 opposite to first semiconductor region 21 and is a p-type polysilicon layer containing a p-type dopant (e.g., boron) as a second conductivity type different from the first conductivity type.
  • a p-type dopant e.g., boron
  • P-type polysilicon layer 10C includes region 10C1 (oxide film side region) as a second region on the side of silicon oxide film 3 that is in contact with silicon oxide film 3.
  • region 10C1 oxide film side region
  • the distribution of the concentration of the p-type dopant (e.g., boron) in the first thickness direction from the surface of the p-type polysilicon layer 10C opposite the silicon substrate 2C toward the silicon substrate 2C has a maximum first peak and a second peak.
  • the second peak is located at a position 3 nm or more away from the position showing the first peak in the direction from the first semiconductor region 21 through the silicon oxide film 3 toward the oxide film side region 10C1.
  • the solar cell element 1C includes a silicon substrate 2C and a p-type polysilicon layer 10C.
  • the silicon substrate 2C has a first semiconductor region 21 as a first region, which is a region of an n-type semiconductor as a first conductivity type.
  • the p-type polysilicon layer 10C is a p-type polysilicon layer that is in contact with the silicon substrate 2C and contains a p-type dopant (e.g., boron) as a second conductivity type different from the first conductivity type.
  • the silicon substrate 2C includes a silicon oxide film 3.
  • the silicon oxide film 3 is an oxide film that is located between the first semiconductor region 21 and the p-type polysilicon layer 10C and is in contact with each of the first semiconductor region 21 and the p-type polysilicon layer 10C.
  • the p-type polysilicon layer 10C includes a region (oxide film side region) 10C1 as a second region on the side of the silicon oxide film 3 that is in contact with the silicon oxide film 3.
  • the distribution of the concentration of the p-type dopant (e.g., boron) in the first thickness direction from the surface of the p-type polysilicon layer 10C opposite the silicon substrate 2C toward the silicon substrate 2C has a maximum first peak and a second peak.
  • the second peak is located at a position 3 nm or more away from the position showing the first peak in the direction from the first semiconductor region 21 through the silicon oxide film 3 toward the oxide film side region 10C1.
  • the solar cell element 1C having any of the above-mentioned configurations 1c and 2c can be said to have a configuration suitable for the manufacturing method of the solar cell element 1C that can reduce the occurrence of blisters and local defects caused by blisters when the p-type polysilicon layer 10C is formed as the doped polysilicon layer.
  • the solar cell element 1C having any of the above-mentioned configurations 1c and 2c can be said to have a configuration suitable for the manufacturing method of the solar cell element 1C that can reduce the occurrence of blisters and local defects caused by blisters when the p-type polysilicon layer 10C is formed as the doped polysilicon layer by undergoing the deposition of the p-type amorphous silicon layer as the doped amorphous silicon layer and the heat treatment for crystallization of the p-type amorphous silicon layer.
  • the solar cell element 1C having any of the above-mentioned configurations 1c and 2c can be said to have a configuration suitable for the manufacturing method of the solar cell element 1C that can reduce defects in the solar cell element 1C having an example of a POLO structure formed using a doped amorphous silicon layer. Therefore, by adopting a solar cell element 1C having any one of the above configurations 1c and 2c, defects in the solar cell element 1C having an example of a POLO structure formed using a doped amorphous silicon layer can be reduced. From another perspective, defects in the solar cell element 1C can be easily reduced.
  • the distribution of the concentration of the p-type dopant (e.g., boron) in the first thickness direction from the surface of the p-type polysilicon layer 10C opposite the silicon substrate 2C toward the silicon substrate 2C in the region from the oxide film side region 10C1 of the p-type polysilicon layer 10C through the silicon oxide film 3 to the first semiconductor region 21 may be the result of measurement using, for example, SIMS.
  • the oxide film side region 10C1 may be the region closest to the silicon oxide film 3 among the N regions.
  • N may be, for example, two, three, or any number equal to or greater than four.
  • the any number equal to or greater than four may be six.
  • the oxide film side region 10C1 may be a region of the p-type polysilicon layer 10C that is 10 nm or less away from the silicon oxide film 3.
  • the second peak may be present at a position 3 nm to 10 nm away from the position showing the first peak in the direction from the first semiconductor region 21 through the silicon oxide film 3 toward the oxide film side region 10C1.
  • the second peak may be present at a position 3 nm to 8 nm away from the position showing the first peak, or may be present at a position 3 nm to 7 nm away from the position showing the first peak, in the direction from the first semiconductor region 21 through the silicon oxide film 3 toward the oxide film side region 10C1.
  • the solar cell element 1D according to the fifth embodiment includes, for example, an example of a POLO structure according to the above-mentioned structure 4 on the surface (front surface) 1f side of the solar cell element 1D facing the +Z direction.
  • the solar cell element 1D according to the fifth embodiment includes, for example, an example of a TOPCon structure, which is a type of POLO structure according to the above-mentioned structure 1, on the surface (back surface) 1b side of the solar cell element 1D facing the -Z direction.
  • the solar cell element 1D according to the fifth embodiment is based on the solar cell element 1 according to the first embodiment, and has a configuration in which the portion of the second semiconductor region 22 between the second electrode 9 and the first semiconductor region 21 is changed to a p-type polysilicon layer 10D, and a silicon oxide film 3D is added as an oxide film between the p-type polysilicon layer 10D and the first semiconductor region 21.
  • the p-type polysilicon layer 10D is a p-type polysilicon layer containing a p-type dopant as a second conductivity type.
  • the solar cell element 1D according to the fifth embodiment includes a structure in which, for example, on the front surface 1f side, a silicon oxide film 3D and a p-type polysilicon layer 10D are stacked in the described order on the first semiconductor region 21.
  • the solar cell element 1D includes a silicon substrate 2 having a first semiconductor region 21 and a p-type polysilicon layer 10D. Furthermore, the solar cell element 1D may include a silicon oxide film 3D that is in contact with the first semiconductor region 21 in addition to the silicon substrate 2, or the silicon substrate 2 may include a silicon oxide film 3D that is located between the first semiconductor region 21 and the p-type polysilicon layer 10D and in contact with each of the first semiconductor region 21 and the p-type polysilicon layer 10D.
  • the first semiconductor region 21 is a first region as a region of n-type semiconductor, which is a first conductivity type, in the silicon substrate 2 as a substrate.
  • the silicon oxide film 3D may be an oxide film that is located inside the silicon substrate 2 and is located along the surface of the silicon substrate 2 or on the surface of the silicon substrate 2 and is in contact with the first semiconductor region 21.
  • the p-type polysilicon layer 10D is a polysilicon layer that contacts the surface of the silicon oxide film 3D opposite to the first semiconductor region 21 and contains a p-type dopant as the second conductive type.
  • the solar cell element 1D includes a structure in which the first semiconductor region 21 as the n-type first region, the silicon oxide film 3D as the oxide film, and the p-type polysilicon layer 10D as the p-type polysilicon layer are stacked in the order described above, as an example of the POLO structure according to the above structure 4.
  • an example of a TOPCon structure as a type of POLO structure according to the above structure 1 on the back surface 1b side of the solar cell element 1D according to the fifth embodiment has substantially the same configuration as an example of a TOPCon structure as a type of POLO structure according to the above structure 1 on the back surface 1b side of the solar cell element 1 according to the first embodiment. Therefore, an example of a TOPCon structure as a type of POLO structure according to the above structure 1 on the back surface 1b side of the solar cell element 1D according to the fifth embodiment can be formed by substantially the same method as an example of a TOPCon structure as a type of POLO structure according to the above structure 1 on the back surface 1b side of the solar cell element 1 according to the first embodiment.
  • FIG. 42 is a flow chart showing an example of a method for manufacturing a solar cell element 1D according to the fifth embodiment.
  • the processes of steps S1D to S10D in FIG. 42 are performed in the order shown, thereby manufacturing the solar cell element 1D.
  • a silicon substrate 2 is prepared.
  • a substrate of crystalline silicon doped with an n-type dopant e.g., phosphorus
  • an n-type dopant e.g., phosphorus
  • a textured structure is formed on the first surface 2f of the silicon substrate 2.
  • a textured structure can be formed on the first surface 2f of the silicon substrate 2 by the same process as step S2 in FIG. 3 according to the first embodiment.
  • the second semiconductor region 22 is formed in a portion located on the inside of the silicon substrate 2 and along the first surface 2f having a textured structure.
  • the second semiconductor region 22 can be formed in a portion located on the inside of the silicon substrate 2 and along the first surface 2f having a textured structure by the same process as step S3 of FIG. 3 according to the first embodiment.
  • p-type region a region of p-type crystalline silicon as the second conductivity type is also formed in a portion located on the inside of the silicon substrate 2 and along the second surface 2b, this p-type region is removed by etching using an aqueous solution of fluoro-nitric acid or the like.
  • boron glass is attached to the first surface 2f side of the silicon substrate 2 when the second semiconductor region 22 is formed, this boron glass is removed by etching.
  • a diffusion mask may be formed in advance on the second surface 2b side of the silicon substrate 2, the second semiconductor region 22 may be formed by a vapor phase thermal diffusion method or the like, and then the diffusion mask may be removed.
  • a portion of the second semiconductor region 22 is locally removed, for example, by placing a mask and etching using an aqueous solution of hydrofluoric and nitric acid.
  • a silicon oxide film is formed on each of the first surface 2f side and the second surface 2b side of the silicon substrate 2.
  • a silicon oxide film is formed along the entire surface of the first surface 2f and the entire surface of the second surface 2b of the silicon substrate 2.
  • a silicon oxide film 3 is formed on the second surface 2b side of the silicon substrate 2, and a silicon oxide film including a portion of the silicon oxide film 3D is formed on the first surface 2f side of the silicon substrate 2.
  • the silicon oxide film 3D is located on the area of the first surface 2f of the silicon substrate 2 where the second semiconductor region 22 is not formed. In other words, the silicon oxide film 3D is located on the first semiconductor region 21 of the silicon substrate 2.
  • a step of forming the silicon oxide film 3D in contact with the first semiconductor region 21 of the silicon substrate 2 is performed.
  • a step of forming the silicon oxide film 3 in contact with the first semiconductor region 21 of the silicon substrate 2 is performed.
  • a silicon oxide film may be formed on the portion located inside the silicon substrate 2 and along the surface of the silicon substrate 2, or a silicon oxide film may be formed on the surface of the silicon substrate 2.
  • the silicon oxide film may be formed by one method or a combination of two or more methods selected from the group consisting of a chemical reaction method, a thermal reaction method, a CVD method, an ALD method, a plasma reaction method, a steam oxidation method, and an ozone oxidation method.
  • the thickness of the silicon oxide film may be set to, for example, 3 nm or less, or 2 nm or less.
  • a p-type polysilicon layer 10D is formed on the silicon oxide film 3D as part of the silicon oxide film on the first surface 2f side of the silicon substrate 2.
  • a p-type polysilicon layer 10D is formed locally on a part of the silicon oxide film on the first surface 2f side of the silicon substrate 2.
  • the local formation of the p-type polysilicon layer 10D can be achieved, for example, by placing a mask.
  • the processes of steps S51D to S53D are performed in the order described above, so that the p-type polysilicon layer 10D can be formed.
  • step S51D as a third example of the second process, a process is carried out in which an intrinsic crystalline silicon layer is formed on the silicon oxide film 3D as a layer of intrinsic crystalline silicon (also referred to as the third first layer).
  • an intrinsic crystalline silicon layer is formed locally on a portion of the silicon oxide film on the first surface 2f side of the silicon substrate 2.
  • an intrinsic crystalline silicon layer can be formed locally on a portion of the silicon oxide film on the first surface 2f side of the silicon substrate 2 by substantially the same process as step S41B of FIG. 39 according to the third embodiment.
  • step S52D as a third example of the third step, a step of forming a p-type amorphous silicon layer on the intrinsic crystalline silicon layer is carried out.
  • the p-type amorphous silicon layer has a thickness greater than that of the intrinsic crystalline silicon layer, and corresponds to a layer of amorphous silicon (also referred to as the third second layer) containing a p-type dopant as the second conductivity type.
  • the p-type amorphous silicon layer is formed, for example, by using a PECVD method.
  • the p-type amorphous silicon layer can be formed on the intrinsic crystalline silicon layer by substantially the same process as step S42B of FIG. 39 according to the third embodiment.
  • step S53D as a third example of the fourth step, a step of forming a p-type polysilicon layer 10D by heat treatment is performed.
  • the p-type polysilicon layer 10D can be formed by substantially the same heat treatment as step S43B of FIG. 39 according to the third embodiment.
  • the intrinsic crystalline silicon layer and the p-type amorphous silicon layer stacked on the silicon oxide film 3D are transformed into the p-type polysilicon layer 10D.
  • a heat treatment is performed to promote crystallization of the amorphous silicon of the p-type amorphous silicon layer while diffusing the p-type dopant contained in the p-type amorphous silicon layer toward the intrinsic crystalline silicon layer and the silicon oxide film 3D.
  • a p-type polysilicon layer 10D located on the silicon oxide film 3D and containing a p-type dopant can be generated from the intrinsic crystalline silicon layer and the p-type amorphous silicon layer.
  • step S5D before a p-type amorphous silicon layer is formed as the third second layer of amorphous silicon containing a second conductive type dopant, an intrinsic crystalline silicon layer having a thickness smaller than that of the p-type amorphous silicon layer is formed on the silicon oxide film 3D.
  • step S5D when the p-type polysilicon layer 10D is formed on the silicon oxide film 3D, an intrinsic crystalline silicon layer is formed on the silicon oxide film 3D, and a p-type amorphous silicon layer is further formed on the intrinsic crystalline silicon layer, and then the p-type polysilicon layer 10D is generated from the intrinsic crystalline silicon layer and the p-type amorphous silicon layer by heat treatment.
  • step S6D an etching process is performed on the first surface 2f side of the silicon substrate 2, and the remaining portion of the silicon oxide film on the first surface 2f side of the silicon substrate 2 is removed, except for the silicon oxide film 3D covered with the p-type polysilicon layer 10D. This can make the silicon oxide film 3D visible.
  • step S7D an n-type polysilicon layer 4 is formed on the silicon oxide film 3.
  • step S7D for example, based on the processing of step S6B in the third embodiment, the silicon substrate 2B and the first semiconductor region 21A are changed to the silicon substrate 2 and the first semiconductor region 21. More specifically, for example, based on the processing of steps S61B to S63B in the third embodiment, in step S7D, the processing of steps S71D to S73D is performed in which the silicon substrate 2B and the first semiconductor region 21A are changed to the silicon substrate 2 and the first semiconductor region 21.
  • step S71D as a fourth example of the second step, a step of forming an intrinsic crystalline silicon layer 4a as an intrinsic crystalline silicon layer (also referred to as the fourth first layer) on the silicon oxide film 3 is performed.
  • step S72D as a fourth example of the third process, a process is performed in which an n-type amorphous silicon layer 4b is formed on the intrinsic crystalline silicon layer 4a as an amorphous silicon layer (also called the fourth second layer) that has a thickness greater than that of the intrinsic crystalline silicon layer 4a and contains an n-type dopant as a first conductivity type dopant.
  • step S73D as a fourth example of the fourth process, a process is performed in which an n-type polysilicon layer 4 is formed by heat treatment.
  • step S7D for example, as in step S6B of the third embodiment, when the n-type polysilicon layer 4 is formed on the silicon oxide film 3, an intrinsic crystalline silicon layer 4a is formed on the silicon oxide film 3, and an n-type amorphous silicon layer 4b is further formed on the intrinsic crystalline silicon layer 4a, and then the n-type polysilicon layer 4 is generated from the intrinsic crystalline silicon layer 4a and the n-type amorphous silicon layer 4b by heat treatment.
  • This can reduce the occurrence of blisters at the interface between the silicon oxide film 3 and the n-type polysilicon layer 4, and can reduce the occurrence of local defects in the n-type polysilicon layer 4 caused by the blisters.
  • the n-type polysilicon layer 4 is formed as a doped polysilicon layer using a PECVD method or the like, the occurrence of blisters and the occurrence of local defects caused by blisters can be reduced.
  • defects can be reduced in the solar cell element 1D having an example of a TOPCon structure, which is a type of POLO structure according to the above structure 1 formed using a doped amorphous silicon layer. From another perspective, defects in the solar cell element 1D can be easily reduced.
  • the reduction in the area on the surface of the silicon substrate 2 where the TOPCon structure, which is a type of POLO structure according to the above-mentioned structure 1 in which the n-type first semiconductor region 21, the silicon oxide film 3, and the n-type polysilicon layer 4 are stacked in this order, exists can be reduced.
  • This can reduce the degradation of passivation performance due to the TOPCon structure, which is a type of POLO structure, in the solar cell element 1D according to the fifth embodiment.
  • the conversion efficiency of the solar cell element 1D can be easily improved.
  • a passivation film 7 is formed on the first surface 2f of the silicon substrate 2.
  • the passivation film 7 is formed over the entire surface of the first surface 2f of the silicon substrate 2.
  • an aluminum oxide layer may be formed as the passivation film 7 by the ALD method, or a silicon oxide layer may be formed as the passivation film 7 by the PECVD method.
  • an anti-reflection film is formed on each of the first surface 2f and the second surface 2b of the silicon substrate 2.
  • a first anti-reflection film 5 is formed over the entire surface of the n-type polysilicon layer 4 opposite the silicon substrate 2
  • a second anti-reflection film 8 is formed over the entire surface of the passivation film 7 opposite the silicon substrate 2.
  • a silicon nitride layer may be formed as the anti-reflection film by the PECVD method.
  • step S10D electrodes are formed on both the first surface 2f and the second surface 2b of the silicon substrate 2.
  • a first electrode 6 is formed on the second surface 2b of the silicon substrate 2
  • a second electrode 9 is formed on the first surface 2f of the silicon substrate 2.
  • a process is performed in which the p-type polysilicon layer 10B is changed to a p-type polysilicon layer 10D.
  • an example of the POLO structure according to structure 4 in solar cell element 1D according to the fifth embodiment can be formed by processing in accordance with steps S4D and S5D in FIG. 42. More specifically, for example, an example of the POLO structure according to structure 4 in solar cell element 1D according to the fifth embodiment can be formed by a manufacturing method for solar cell element 1D having the following steps 1d, 2d, 3d, and 4d.
  • a silicon oxide film 3D is formed as an oxide film in contact with the first semiconductor region 21 located inside a silicon substrate 2 as a crystalline silicon substrate including a first region that is an n-type semiconductor region as a first conductivity type and along the surface of the silicon substrate 2 or on the surface of the silicon substrate 2.
  • Step 2d An intrinsic crystalline silicon layer is formed on the silicon oxide film 3D as the first layer (third first layer) of intrinsic crystalline silicon.
  • a p-type amorphous silicon layer is formed on the intrinsic crystalline silicon layer as a second layer (third second layer) of amorphous silicon having a thickness greater than that of the intrinsic crystalline silicon layer and containing a p-type dopant (e.g., boron) as a second conductivity type different from the first conductivity type.
  • the p-type amorphous silicon layer may be formed, for example, by using a PECVD method.
  • Step 4d A heat treatment is performed to diffuse the p-type dopant (e.g., boron) contained in the p-type amorphous silicon layer toward the intrinsic crystalline silicon layer and silicon oxide film 3D while promoting the crystallization of the amorphous silicon of the p-type amorphous silicon layer.
  • a p-type polysilicon layer 10D is generated from the intrinsic crystalline silicon layer and the p-type amorphous silicon layer as a polysilicon layer located on the silicon oxide film 3D and containing a p-type dopant (e.g., boron).
  • step 1d is an example of the first step of the present disclosure.
  • the above step 2d is an example of the second step of the present disclosure.
  • the above step 3d is an example of the third step of the present disclosure.
  • the above step 4d is an example of the fourth step of the present disclosure.
  • the intrinsic crystalline silicon layer is formed on the silicon oxide film 3D, so that the adhesion between the silicon oxide film 3D and the intrinsic crystalline silicon layer can be improved.
  • the p-type amorphous silicon layer is formed on the intrinsic crystalline silicon layer, when the intrinsic crystalline silicon layer and the p-type amorphous silicon layer are transformed into the p-type polysilicon layer 10D as a doped polysilicon layer by heat treatment, the adhesion of the interface between the silicon oxide film 3D and the p-type polysilicon layer 10D can be ensured.
  • defects can be reduced in the solar cell element 1D having an example of a POLO structure formed using the doped amorphous silicon layer. From another perspective, defects in the solar cell element 1D can be easily reduced.
  • the solar cell element 1D manufactured by the manufacturing method of the solar cell element 1D according to the fifth embodiment in which the above steps 1d to 4d are performed can be said to be an element having either of the following configurations 5d and 6d.
  • Solar cell element 1D comprises a silicon substrate 2, a silicon oxide film 3D, and a p-type polysilicon layer 10D.
  • Silicon substrate 2 has a first semiconductor region 21 as a first region which is a region of n-type semiconductor as a first conductivity type.
  • Silicon oxide film 3D is an oxide film in contact with first semiconductor region 21.
  • P-type polysilicon layer 10D is in contact with the surface of silicon oxide film 3D opposite first semiconductor region 21 and is a p-type polysilicon layer containing a p-type dopant (e.g., boron) as a second conductivity type different from the first conductivity type.
  • a p-type dopant e.g., boron
  • the p-type polysilicon layer 10D is a layer formed from the intrinsic crystalline silicon layer and the p-type amorphous silicon layer by performing a heat treatment on the intrinsic crystalline silicon layer as the first layer of intrinsic crystalline silicon located on the silicon oxide film 3D and the p-type amorphous silicon layer as the second layer of amorphous silicon located on the intrinsic crystalline silicon layer, having a thickness greater than that of the intrinsic crystalline silicon layer, and containing a p-type dopant (e.g., boron).
  • a p-type dopant e.g., boron
  • This heat treatment is a process that progresses the crystallization of the amorphous silicon of the p-type amorphous silicon layer while diffusing the p-type dopant (e.g., boron) contained in the p-type amorphous silicon layer toward the intrinsic crystalline silicon layer and the silicon oxide film 3D.
  • p-type dopant e.g., boron
  • Solar cell element 1D comprises a silicon substrate 2 and a p-type polysilicon layer 10D.
  • Silicon substrate 2 has a first semiconductor region 21 as a first region which is a region of n-type semiconductor as a first conductivity type.
  • P-type polysilicon layer 10D is in contact with silicon substrate 2 and is a p-type polysilicon layer containing a p-type dopant (e.g., boron) as a second conductivity type different from the first conductivity type.
  • Silicon substrate 2 includes silicon oxide film 3D.
  • Silicon oxide film 3D is an oxide film located between first semiconductor region 21 and p-type polysilicon layer 10D and in contact with both first semiconductor region 21 and p-type polysilicon layer 10D.
  • the p-type polysilicon layer 10D is a layer formed from the intrinsic crystalline silicon layer and the p-type amorphous silicon layer by performing a heat treatment on the intrinsic crystalline silicon layer as the first layer of intrinsic crystalline silicon located on the silicon oxide film 3D and the p-type amorphous silicon layer as the second layer of amorphous silicon located on the intrinsic crystalline silicon layer, having a thickness greater than that of the intrinsic crystalline silicon layer, and containing a p-type dopant (e.g., boron).
  • a p-type dopant e.g., boron
  • This heat treatment is a process that progresses the crystallization of the amorphous silicon of the p-type amorphous silicon layer while diffusing the p-type dopant (e.g., boron) contained in the p-type amorphous silicon layer toward the intrinsic crystalline silicon layer and the silicon oxide film 3D.
  • p-type dopant e.g., boron
  • the solar cell element 1D having any of the above configurations 5d and 6d can be said to have a configuration suitable for the manufacturing method of the solar cell element 1D that can reduce the occurrence of blisters and local defects caused by blisters when the p-type polysilicon layer 10D is formed as the doped polysilicon layer.
  • the solar cell element 1D having any of the above configurations 5d and 6d can be said to have a configuration suitable for the manufacturing method of the solar cell element 1D that can reduce the occurrence of blisters and local defects caused by blisters when the p-type polysilicon layer 10D is formed as the doped polysilicon layer by undergoing the formation of the p-type amorphous silicon layer as the doped amorphous silicon layer and the heat treatment for crystallization of the p-type amorphous silicon layer.
  • the solar cell element 1D having any of the above configurations 5d and 6d can be said to have a configuration suitable for the manufacturing method of the solar cell element 1D that can reduce defects in the solar cell element 1D having an example of a POLO structure formed using a doped amorphous silicon layer. Therefore, by adopting a solar cell element 1D having any one of the above configurations 5d and 6d, defects in the solar cell element 1D having an example of a POLO structure formed using a doped amorphous silicon layer can be reduced. From another perspective, defects in the solar cell element 1D can be easily reduced.
  • an intrinsic crystalline silicon layer is formed on a silicon oxide film, and a p-type amorphous silicon layer is further formed on the intrinsic crystalline silicon layer, and then a p-type polysilicon layer 10C is generated from the intrinsic crystalline silicon layer and the p-type amorphous silicon layer by heat treatment.
  • an intrinsic crystalline silicon layer is formed on a silicon oxide film, and a p-type amorphous silicon layer is further formed on the intrinsic crystalline silicon layer, and then a p-type polysilicon layer 10D is generated from the intrinsic crystalline silicon layer and the p-type amorphous silicon layer by heat treatment.
  • the method for forming an example of a POLO structure relating to structure 4 in the fourth embodiment is substantially the same as the method for forming an example of a POLO structure relating to structure 4 in the fifth embodiment.
  • the solar cell element 1D manufactured by the manufacturing method of the solar cell element 1D according to the fifth embodiment can be an element having either of the following configurations 1d and 2d.
  • Solar cell element 1D comprises a silicon substrate 2, a silicon oxide film 3D, and a p-type polysilicon layer 10D.
  • Silicon substrate 2 has a first semiconductor region 21 as a first region which is a region of n-type semiconductor as a first conductivity type.
  • Silicon oxide film 3D is an oxide film in contact with first semiconductor region 21.
  • P-type polysilicon layer 10D is in contact with the surface of silicon oxide film 3D opposite to first semiconductor region 21, and is a p-type polysilicon layer containing a p-type dopant (e.g., boron) as a second conductivity type different from the first conductivity type.
  • a p-type dopant e.g., boron
  • P-type polysilicon layer 10D includes a region (oxide film side region) 10D1 as a second region on the side of silicon oxide film 3D in contact with silicon oxide film 3D.
  • the distribution of the concentration of the p-type dopant (e.g., boron) in the second thickness direction which is the direction from the surface of the p-type polysilicon layer 10D on the side opposite the silicon substrate 2 toward the silicon substrate 2
  • the second peak is located at a position 3 nm or more away from the position showing the first peak in the direction from the first semiconductor region 21 through the silicon oxide film 3D toward the oxide film side region 10D1.
  • the solar cell element 1D comprises a silicon substrate 2 and a p-type polysilicon layer 10D.
  • the silicon substrate 2 has a first semiconductor region 21 as a first region, which is a region of an n-type semiconductor as a first conductivity type.
  • the p-type polysilicon layer 10D is a p-type polysilicon layer that is in contact with the silicon substrate 2 and contains a p-type dopant (e.g., boron) as a second conductivity type different from the first conductivity type.
  • the silicon substrate 2 includes a silicon oxide film 3D.
  • the silicon oxide film 3D is an oxide film that is located between the first semiconductor region 21 and the p-type polysilicon layer 10D and is in contact with each of the first semiconductor region 21 and the p-type polysilicon layer 10D.
  • the p-type polysilicon layer 10D includes a region (oxide film side region) 10D1 as a second region on the side of the silicon oxide film 3D that is in contact with the silicon oxide film 3D.
  • the distribution of the concentration of the p-type dopant (e.g., boron) in the second thickness direction which is the direction from the surface of the p-type polysilicon layer 10D on the side opposite the silicon substrate 2 toward the silicon substrate 2
  • the second peak is located at a position 3 nm or more away from the position showing the first peak in the direction from the first semiconductor region 21 through the silicon oxide film 3D toward the oxide film side region 10D1.
  • the solar cell element 1D having any of the above-mentioned configurations 1d and 2d can be said to have a configuration suitable for the manufacturing method of the solar cell element 1D that can reduce the occurrence of blisters and local defects caused by blisters when the p-type polysilicon layer 10D is formed as the doped polysilicon layer.
  • the solar cell element 1D having any of the above-mentioned configurations 1d and 2d can be said to have a configuration suitable for the manufacturing method of the solar cell element 1D that can reduce the occurrence of blisters and local defects caused by blisters when the p-type polysilicon layer 10D is formed as the doped polysilicon layer by undergoing the deposition of the p-type amorphous silicon layer as the doped amorphous silicon layer and the heat treatment for crystallization of the p-type amorphous silicon layer.
  • the solar cell element 1D having any of the above-mentioned configurations 1d and 2d can be said to have a configuration suitable for the manufacturing method of the solar cell element 1D that can reduce defects in the solar cell element 1D having an example of a POLO structure formed using a doped amorphous silicon layer. Therefore, by adopting a solar cell element 1D having any one of the above configurations 1d and 2d, defects in the solar cell element 1D having an example of a POLO structure formed using a doped amorphous silicon layer can be reduced. From another perspective, defects in the solar cell element 1D can be easily reduced.
  • the distribution of the concentration of the p-type dopant (e.g., boron) in the second thickness direction, which is the direction from the surface of the p-type polysilicon layer 10D opposite the silicon substrate 2 toward the silicon substrate 2, in the region from the oxide film side region 10D1 of the p-type polysilicon layer 10D through the silicon oxide film 3D to the first semiconductor region 21 may be the result of measurement using, for example, SIMS.
  • the concentration of the p-type dopant e.g., boron
  • the oxide film side region 10D1 may be the region closest to the silicon oxide film 3D among the N regions.
  • N may be, for example, two, three, or any number equal to or greater than four.
  • the any number equal to or greater than four may be six.
  • the oxide film side region 10D1 may be a region of the p-type polysilicon layer 10D that is 10 nm or less away from the silicon oxide film 3D.
  • the second peak may be present at a position 3 nm to 10 nm away from the position showing the first peak in the direction from the first semiconductor region 21 through the silicon oxide film 3D toward the oxide film side region 10D1.
  • the second peak may be present at a position 3 nm to 8 nm away from the position showing the first peak, or may be present at a position 3 nm to 7 nm away from the position showing the first peak, in the direction from the first semiconductor region 21 through the silicon oxide film 3D toward the oxide film side region 10D1.
  • the intrinsic crystalline silicon layer formed on the oxide film when the POLO structure is formed may be a microcrystalline silicon layer.
  • the microcrystalline silicon layer may be formed by, for example, a PECVD method using silane (SiH 4 ) gas and hydrogen (H 2 ) gas as raw materials. Even when the intrinsic crystalline silicon layer is a microcrystalline silicon layer when the POLO structure is formed, it has been confirmed that the occurrence of blisters at the interface between the oxide film and the doped polysilicon layer, as well as the occurrence of local defects in the doped polysilicon layer caused by the blisters, are reduced.
  • the intrinsic crystalline silicon layer is a microcrystalline silicon layer
  • the adhesion between the intrinsic crystalline silicon layer and the oxide film is increased.
  • the amorphous silicon layer shrinks during heat treatment for crystallization
  • the microcrystalline silicon layer is less likely to shrink even when heat treatment is applied, and therefore is less likely to peel off from the oxide film and less likely to burst.
  • the intrinsic crystalline silicon layer formed on the oxide film when the POLO structure is formed may be formed by passing through an amorphous silicon layer on the oxide film as described above, or may be formed directly as an intrinsic polycrystalline silicon layer without passing through an intrinsic amorphous silicon layer on the oxide film.
  • the intrinsic polycrystalline silicon layer can be formed directly on the oxide film by the LPCVD method or deposition method using silane gas and hydrogen gas as raw materials. Even in this case, it was confirmed that the occurrence of blisters at the interface between the oxide film and the doped polysilicon layer, as well as the occurrence of local defects in the doped polysilicon layer due to these blisters, is reduced.
  • the intrinsic polycrystalline silicon layer can be formed in a state where the hydrogen concentration is lower than that of the intrinsic amorphous silicon layer, so that the crystalline silicon layer has a higher adhesion to the oxide film than the amorphous silicon layer. Furthermore, while an amorphous silicon layer shrinks during heat treatment for crystallization, a crystalline silicon layer is less likely to shrink when heat treatment is applied, and is therefore less likely to peel off from the oxide film and to burst. As a result, it was estimated that the occurrence of blisters and the occurrence of localized defects in the doped polysilicon layer due to blisters can be reduced.
  • the intrinsic crystalline silicon layer formed on the oxide film when the POLO structure is formed may be composed of two or more layers of microcrystalline silicon, may be composed of two or more layers of polycrystalline silicon, or may be a layer having a structure in which one or more layers of microcrystalline silicon and one or more layers of polycrystalline silicon are stacked.
  • observation may be performed using a metal microscope or the like to target the cut surfaces of the solar cell elements 1, 1A, 1B, 1C, and 1D to confirm the presence or absence of voids at the interface between the oxide film and the doped polysilicon layer, thereby confirming the presence or absence of blisters in the solar cell elements 1, 1A, 1B, 1C, and 1D.
  • the method for forming the n-type amorphous silicon layer 4b or the p-type amorphous silicon layer on the intrinsic crystalline silicon layer formed on the silicon oxide films 3, 3B, 3D is not limited to the PECVD method, but may be other methods such as a vapor deposition method.
  • the first electrode 6 is located on the back surface 1b side and the second electrode 9 is located on the front surface 1f side, but this is not limited to the above.
  • a solar cell element in which both the first electrode 6 and the second electrode 9 are located on the back surface side may be used.
  • a solar cell element having this configuration for example, a back contact type solar cell element having an IBC (Interdigitated Back Contact) structure is used.
  • the back-contact type solar cell element having this IBC structure may have a POLO structure (also called a first POLO structure) including a doped polysilicon layer located between the crystalline silicon substrate and the first electrode 6, or may have a POLO structure (also called a second POLO structure) including a doped polysilicon layer located between the crystalline silicon substrate and the second electrode 9, within the scope in which the solar cell function is realized.
  • a POLO structure also called a first POLO structure
  • POLO structure also called a second POLO structure
  • the POLO structure of Structure 1 When the POLO structure of Structure 1 is applied to either the first POLO structure or the second POLO structure, the POLO structure of Structure 1 may be formed by carrying out the first to fourth steps described below in the order described. In other words, the manufacturing method of a solar cell element may have the first, second, third and fourth steps described below. As a result, defects can be reduced in a solar cell element having the POLO structure of Structure 1, which is formed using an n-type amorphous silicon layer as a doped amorphous silicon layer, as in the first and fifth embodiments described above.
  • a silicon oxide film is formed as an oxide film in contact with a first semiconductor region, which is a region of an n-type semiconductor as a first conductivity type, located inside the silicon substrate as a substrate of crystalline silicon and in a portion along the surface of the silicon substrate or on the surface of the silicon substrate.
  • An intrinsic crystalline silicon layer is formed on the silicon oxide film as the first layer of intrinsic crystalline silicon.
  • n-type amorphous silicon layer is formed on the intrinsic crystalline silicon layer as a second layer of amorphous silicon having a thickness greater than that of the intrinsic crystalline silicon layer and containing an n-type dopant (e.g., phosphorus) as the first conductivity type.
  • the n-type amorphous silicon layer may be formed, for example, by using a PECVD method.
  • a heat treatment is carried out to diffuse the n-type dopant (e.g., phosphorus) contained in the n-type amorphous silicon layer toward the intrinsic crystalline silicon layer and the silicon oxide film while promoting the crystallization of the amorphous silicon of the n-type amorphous silicon layer.
  • n-type dopant e.g., phosphorus
  • an n-type polysilicon layer is generated from the intrinsic crystalline silicon layer and the n-type amorphous silicon layer as a polysilicon layer located on the silicon oxide film and containing an n-type dopant (e.g., phosphorus).
  • the solar cell element may have any of the following first, second, fifth and sixth configurations.
  • defects can be reduced in a solar cell element having the POLO structure of the above-mentioned structure 1 formed using an n-type amorphous silicon layer as a doped amorphous silicon layer, as in the first and fifth embodiments.
  • the solar cell element includes a silicon substrate, a silicon oxide film, and an n-type polysilicon layer.
  • the silicon substrate has a first semiconductor region as a first region, which is a region of n-type semiconductor as a first conductivity type.
  • the silicon oxide film is an oxide film in contact with the first semiconductor region.
  • the n-type polysilicon layer is an n-type polysilicon layer that is in contact with the surface of the silicon oxide film opposite to the first semiconductor region and contains an n-type dopant (e.g., phosphorus).
  • the n-type polysilicon layer includes a region (oxide film side region) as a second region on the side of the silicon oxide film that is in contact with the silicon oxide film.
  • the distribution of the concentration of the n-type dopant (e.g., phosphorus) in the direction (first direction) from the surface of the n-type polysilicon layer opposite to the silicon substrate toward the silicon substrate has a maximum first peak and a second peak.
  • the second peak is located at a position 3 nm or more away from the position of the first peak in the direction from the first semiconductor region through the silicon oxide film toward the oxide film side region.
  • the solar cell element includes a silicon substrate and an n-type polysilicon layer.
  • the silicon substrate has a first semiconductor region as a first region, which is a region of n-type semiconductor as a first conductivity type.
  • the n-type polysilicon layer is an n-type polysilicon layer that is in contact with the silicon substrate and contains an n-type dopant (e.g., phosphorus).
  • the silicon substrate includes a silicon oxide film.
  • the silicon oxide film is an oxide film that is located between the first semiconductor region and the n-type polysilicon layer and is in contact with each of the first semiconductor region and the n-type polysilicon layer.
  • the n-type polysilicon layer includes a region (oxide film side region) as a second region on the side of the silicon oxide film that is in contact with the silicon oxide film.
  • the distribution of the concentration of the n-type dopant (e.g., phosphorus) in the direction (first direction) from the surface of the n-type polysilicon layer opposite the silicon substrate toward the silicon substrate has a maximum first peak and a second peak.
  • the second peak is located at a position 3 nm or more away from the position of the first peak in the direction from the first semiconductor region through the silicon oxide film toward the oxide film side region.
  • the solar cell element includes a silicon substrate, a silicon oxide film, and an n-type polysilicon layer.
  • the silicon substrate has a first semiconductor region as a first region, which is a region of n-type semiconductor as a first conductivity type.
  • the silicon oxide film is an oxide film in contact with the first semiconductor region.
  • the n-type polysilicon layer is an n-type polysilicon layer that is in contact with the surface of the silicon oxide film opposite to the first semiconductor region and contains an n-type dopant (e.g., phosphorus).
  • the n-type polysilicon layer is a layer generated from the intrinsic crystalline silicon layer and the n-type amorphous silicon layer by performing a heat treatment on an intrinsic crystalline silicon layer as a first layer of intrinsic crystalline silicon located on the silicon oxide film, and an n-type amorphous silicon layer as a second layer of amorphous silicon located on the intrinsic crystalline silicon layer, having a thickness greater than that of the intrinsic crystalline silicon layer, and containing an n-type dopant (e.g., phosphorus).
  • an n-type dopant e.g., phosphorus
  • This heat treatment is a process that causes the n-type dopant (e.g., phosphorus) contained in the n-type amorphous silicon layer to diffuse toward the intrinsic crystalline silicon layer and the silicon oxide film, thereby promoting the crystallization of the amorphous silicon in the n-type amorphous silicon layer.
  • n-type dopant e.g., phosphorus
  • the solar cell element includes a silicon substrate and an n-type polysilicon layer.
  • the silicon substrate has a first semiconductor region as a first region, which is a region of an n-type semiconductor as a first conductive type.
  • the n-type polysilicon layer is an n-type polysilicon layer that is in contact with the silicon substrate and contains an n-type dopant (e.g., phosphorus).
  • the silicon substrate includes a silicon oxide film.
  • the silicon oxide film is an oxide film that is located between the first semiconductor region and the n-type polysilicon layer and is in contact with each of the first semiconductor region and the n-type polysilicon layer.
  • the n-type polysilicon layer is a layer generated from the intrinsic crystalline silicon layer and the n-type amorphous silicon layer by performing a heat treatment on an intrinsic crystalline silicon layer as a first layer of intrinsic crystalline silicon located on the silicon oxide film, and an n-type amorphous silicon layer as a second layer of amorphous silicon located on the intrinsic crystalline silicon layer, having a thickness greater than that of the intrinsic crystalline silicon layer, and containing an n-type dopant (e.g., phosphorus).
  • an n-type dopant e.g., phosphorus
  • This heat treatment is a process that promotes the crystallization of the amorphous silicon in the n-type amorphous silicon layer while diffusing the n-type dopant (e.g., phosphorus) contained in the n-type amorphous silicon layer toward the intrinsic crystalline silicon layer and the silicon oxide film.
  • n-type dopant e.g., phosphorus
  • the second peak may be present at a position 3 nm to 10 nm away from the position showing the first peak in the direction from the first semiconductor region through the silicon oxide film toward the oxide film side region.
  • the second peak may be present at a position 3 nm to 8 nm away from the position showing the first peak, or may be present at a position 3 nm to 7 nm away from the position showing the first peak, in the direction from the first semiconductor region through the silicon oxide film toward the oxide film side region.
  • the concentration distribution of the n-type dopant (e.g., phosphorus) in the direction (first direction) from the surface of the n-type polysilicon layer opposite the silicon substrate toward the silicon substrate in the region from the oxide film side region of the silicon oxide film side of the n-type polysilicon layer through the silicon oxide film to the first semiconductor region may be a result measured using, for example, SIMS.
  • the oxide film side region may be the region closest to the silicon oxide film among the N regions (N is a natural number equal to or greater than 2) when the n-type polysilicon layer is equally divided into N regions in a direction (first direction) from the surface of the n-type polysilicon layer opposite the silicon substrate toward the silicon substrate.
  • N may be, for example, 2, 3, or any number equal to or greater than 4.
  • the any number equal to or greater than 4 may be 6.
  • the oxide film side region may be a region of the n-type polysilicon layer that is 10 nm or less away from the silicon oxide film.
  • the POLO structure of Structure 2 When the POLO structure of Structure 2 is applied to either the first POLO structure or the second POLO structure, the POLO structure of Structure 2 may be formed by carrying out the following steps 1A to 4A in the order described.
  • the manufacturing method of a solar cell element may include the following steps 1A, 2A, 3A, and 4A.
  • defects can be reduced in a solar cell element having the POLO structure of Structure 2, which is formed using an n-type amorphous silicon layer as a doped amorphous silicon layer, as in the second and third embodiments.
  • a silicon oxide film is formed as an oxide film in contact with a first semiconductor region, which is a region of a p-type semiconductor as a first conductivity type, located inside the silicon substrate as a substrate of crystalline silicon and in a portion along the surface of the silicon substrate or on the surface of the silicon substrate.
  • Step 2A An intrinsic crystalline silicon layer is formed on the silicon oxide film as the first layer of intrinsic crystalline silicon.
  • Step 3A An n-type amorphous silicon layer is formed on the intrinsic crystalline silicon layer as a second layer of amorphous silicon having a thickness greater than that of the intrinsic crystalline silicon layer and containing an n-type dopant (e.g., phosphorus) as a second conductivity type different from the first conductivity type.
  • the n-type amorphous silicon layer may be formed, for example, by using a PECVD method.
  • Step 4A A heat treatment is carried out to diffuse the n-type dopant (e.g., phosphorus) contained in the n-type amorphous silicon layer toward the intrinsic crystalline silicon layer and the silicon oxide film while promoting the crystallization of the amorphous silicon of the n-type amorphous silicon layer.
  • n-type dopant e.g., phosphorus
  • the solar cell element may have any of the following configurations 1A, 2A, 5A, and 6A.
  • defects can be reduced in a solar cell element having the above-mentioned POLO structure of the above-mentioned structure 2 formed using an n-type amorphous silicon layer as a doped amorphous silicon layer, as in the above-mentioned second and third embodiments.
  • the solar cell element includes a silicon substrate, a silicon oxide film, and an n-type polysilicon layer.
  • the silicon substrate has a first semiconductor region as a first region, which is a region of a p-type semiconductor as a first conductivity type.
  • the silicon oxide film is an oxide film in contact with the first semiconductor region.
  • the n-type polysilicon layer is an n-type polysilicon layer that is in contact with the surface of the silicon oxide film opposite to the first semiconductor region and contains an n-type dopant (e.g., phosphorus) as a second conductivity type different from the first conductivity type.
  • n-type dopant e.g., phosphorus
  • the n-type polysilicon layer includes a region (oxide film side region) as a second region on the side of the silicon oxide film that is in contact with the silicon oxide film.
  • the distribution of the concentration of the n-type dopant (e.g., phosphorus) in the direction (first direction) from the surface of the n-type polysilicon layer opposite to the silicon substrate toward the silicon substrate has a maximum first peak and a second peak.
  • the second peak is located at a position 3 nm or more away from the position of the first peak in the direction from the first semiconductor region through the silicon oxide film toward the oxide film side region.
  • the solar cell element comprises a silicon substrate and an n-type polysilicon layer.
  • the silicon substrate has a first semiconductor region as a first region which is a region of p-type semiconductor as a first conductivity type.
  • the n-type polysilicon layer is an n-type polysilicon layer that is in contact with the silicon substrate and contains an n-type dopant (e.g., phosphorus) as a second conductivity type different from the first conductivity type.
  • the silicon substrate includes a silicon oxide film.
  • the silicon oxide film is an oxide film that is located between the first semiconductor region and the n-type polysilicon layer and is in contact with both the first semiconductor region and the n-type polysilicon layer.
  • the n-type polysilicon layer includes a region (oxide film side region) as a second region on the side of the silicon oxide film that is in contact with the silicon oxide film.
  • the distribution of the concentration of the n-type dopant (e.g., phosphorus) in the direction from the surface of the n-type polysilicon layer opposite the silicon substrate toward the silicon substrate (first direction) has a maximum first peak and a second peak.
  • the second peak is located at a position 3 nm or more away from the position showing the first peak in the direction from the first semiconductor region through the silicon oxide film toward the oxide film side region.
  • the solar cell element includes a silicon substrate, a silicon oxide film, and an n-type polysilicon layer.
  • the silicon substrate has a first semiconductor region as a first region, which is a region of a p-type semiconductor as a first conductivity type.
  • the silicon oxide film is an oxide film in contact with the first semiconductor region.
  • the n-type polysilicon layer is an n-type polysilicon layer that is in contact with the surface of the silicon oxide film opposite to the first semiconductor region and contains an n-type dopant (e.g., phosphorus) as a second conductivity type different from the first conductivity type.
  • n-type dopant e.g., phosphorus
  • the n-type polysilicon layer is a layer generated from the intrinsic crystalline silicon layer and the n-type amorphous silicon layer by performing a heat treatment on an intrinsic crystalline silicon layer as a first layer of intrinsic crystalline silicon located on the silicon oxide film, and an n-type amorphous silicon layer as a second layer of amorphous silicon located on the intrinsic crystalline silicon layer, having a thickness greater than that of the intrinsic crystalline silicon layer, and containing an n-type dopant (e.g., phosphorus).
  • an n-type dopant e.g., phosphorus
  • This heat treatment is a process that causes the n-type dopant (e.g., phosphorus) contained in the n-type amorphous silicon layer to diffuse toward the intrinsic crystalline silicon layer and the silicon oxide film, thereby promoting the crystallization of the amorphous silicon in the n-type amorphous silicon layer.
  • n-type dopant e.g., phosphorus
  • the solar cell element comprises a silicon substrate and an n-type polysilicon layer.
  • the silicon substrate has a first semiconductor region as a first region which is a region of p-type semiconductor as a first conductivity type.
  • the n-type polysilicon layer is an n-type polysilicon layer that is in contact with the silicon substrate and contains an n-type dopant (e.g., phosphorus) as a second conductivity type different from the first conductivity type.
  • the silicon substrate includes a silicon oxide film.
  • the silicon oxide film is an oxide film that is located between the first semiconductor region and the n-type polysilicon layer and is in contact with both the first semiconductor region and the n-type polysilicon layer.
  • the n-type polysilicon layer is a layer formed from the intrinsic crystalline silicon layer and the n-type amorphous silicon layer by performing a heat treatment on the intrinsic crystalline silicon layer as a first layer of intrinsic crystalline silicon located on the silicon oxide film, and the n-type amorphous silicon layer as a second layer of amorphous silicon located on the intrinsic crystalline silicon layer, having a thickness greater than that of the intrinsic crystalline silicon layer, and containing an n-type dopant (e.g., phosphorus).
  • an n-type dopant e.g., phosphorus
  • This heat treatment is a process that progresses the crystallization of the amorphous silicon of the n-type amorphous silicon layer while diffusing the n-type dopant (e.g., phosphorus) contained in the n-type amorphous silicon layer toward the intrinsic crystalline silicon layer and the silicon oxide film.
  • n-type dopant e.g., phosphorus
  • the second peak may be present at a position 3 nm to 10 nm away from the position showing the first peak in the direction from the first semiconductor region through the silicon oxide film toward the oxide film side region.
  • the second peak may be present at a position 3 nm to 8 nm away from the position showing the first peak, or may be present at a position 3 nm to 7 nm away from the position showing the first peak, in the direction from the first semiconductor region through the silicon oxide film toward the oxide film side region.
  • the concentration distribution of the n-type dopant (e.g., phosphorus) in the direction (first direction) from the surface of the n-type polysilicon layer opposite the silicon substrate toward the silicon substrate in the region from the oxide film side region of the silicon oxide film side of the n-type polysilicon layer through the silicon oxide film to the first semiconductor region may be a result measured using, for example, SIMS.
  • the oxide film side region may be the region closest to the silicon oxide film among the N regions (N is a natural number equal to or greater than 2) when the n-type polysilicon layer is equally divided into N regions in a direction (first direction) from the surface of the n-type polysilicon layer opposite the silicon substrate toward the silicon substrate.
  • N may be, for example, 2, 3, or any number equal to or greater than 4.
  • the any number equal to or greater than 4 may be 6.
  • the oxide film side region may be a region of the n-type polysilicon layer that is 10 nm or less away from the silicon oxide film.
  • the POLO structure of Structure 3 When the POLO structure of Structure 3 is applied to either the first POLO structure or the second POLO structure, the POLO structure of Structure 3 may be formed by carrying out the following steps 1B to 4B in the order described.
  • the manufacturing method of a solar cell element may include the following steps 1B, 2B, 3B, and 4B.
  • defects can be reduced in a solar cell element having the POLO structure of Structure 3, which is formed using a p-type amorphous silicon layer as a doped amorphous silicon layer, as in the third embodiment.
  • a silicon oxide film is formed as an oxide film in contact with the first semiconductor region, which is a region of a p-type semiconductor as a first conductivity type, located inside the silicon substrate as a substrate of crystalline silicon and in a portion along the surface of the silicon substrate or on the surface of the silicon substrate.
  • Step 2B An intrinsic crystalline silicon layer is formed on the silicon oxide film as the first layer of intrinsic crystalline silicon.
  • a p-type amorphous silicon layer is formed on the intrinsic crystalline silicon layer as a second layer of amorphous silicon having a thickness greater than that of the intrinsic crystalline silicon layer and containing a p-type dopant (e.g., boron).
  • the p-type amorphous silicon layer may be formed, for example, by using a PECVD method.
  • Step 4B A heat treatment is carried out to diffuse the p-type dopant (e.g., boron) contained in the p-type amorphous silicon layer toward the intrinsic crystalline silicon layer and the silicon oxide film while promoting the crystallization of the amorphous silicon of the p-type amorphous silicon layer.
  • a p-type polysilicon layer is generated from the intrinsic crystalline silicon layer and the p-type amorphous silicon layer as a polysilicon layer located on the silicon oxide film and containing a p-type dopant (e.g., boron).
  • the solar cell element may have any of the following configurations 1B, 2B, 5B, and 6B.
  • defects can be reduced in a solar cell element having the POLO structure of the above structure 3 formed using a p-type amorphous silicon layer as a doped amorphous silicon layer, as in the third embodiment.
  • the solar cell element includes a silicon substrate, a silicon oxide film, and a p-type polysilicon layer.
  • the silicon substrate has a first semiconductor region as a first region, which is a region of a p-type semiconductor as a first conductivity type.
  • the silicon oxide film is an oxide film in contact with the first semiconductor region.
  • the p-type polysilicon layer is a p-type polysilicon layer that is in contact with the surface of the silicon oxide film opposite to the first semiconductor region and contains a p-type dopant (e.g., boron).
  • the p-type polysilicon layer includes a region (oxide film side region) as a second region on the side of the silicon oxide film that is in contact with the silicon oxide film.
  • the distribution of the concentration of the p-type dopant (e.g., boron) in the direction (second direction) from the surface of the p-type polysilicon layer opposite to the silicon substrate toward the silicon substrate has a maximum first peak and a second peak.
  • the second peak is located at a position 3 nm or more away from the position of the first peak in the direction from the first semiconductor region through the silicon oxide film toward the oxide film side region.
  • the solar cell element comprises a silicon substrate and a p-type polysilicon layer.
  • the silicon substrate has a first semiconductor region as a first region which is a region of p-type semiconductor as a first conductivity type.
  • the p-type polysilicon layer is a p-type polysilicon layer that is in contact with the silicon substrate and contains a p-type dopant (e.g., boron).
  • the silicon substrate includes a silicon oxide film.
  • the silicon oxide film is an oxide film that is located between the first semiconductor region and the p-type polysilicon layer and is in contact with both the first semiconductor region and the p-type polysilicon layer.
  • the p-type polysilicon layer includes a region (oxide film side region) as a second region on the side of the silicon oxide film that is in contact with the silicon oxide film.
  • the distribution of the concentration of the p-type dopant e.g., boron
  • the second peak is located at a position 3 nm or more away from the position showing the first peak in the direction from the first semiconductor region through the silicon oxide film toward the oxide film side region.
  • the solar cell element includes a silicon substrate, a silicon oxide film, and a p-type polysilicon layer.
  • the silicon substrate has a first semiconductor region as a first region, which is a region of a p-type semiconductor as a first conductivity type.
  • the silicon oxide film is an oxide film in contact with the first semiconductor region.
  • the p-type polysilicon layer is a p-type polysilicon layer that is in contact with the surface of the silicon oxide film opposite to the first semiconductor region and contains a p-type dopant (e.g., boron).
  • the p-type polysilicon layer is a layer generated from the intrinsic crystalline silicon layer and the p-type amorphous silicon layer by performing a heat treatment on an intrinsic crystalline silicon layer as a first layer of intrinsic crystalline silicon located on the silicon oxide film, and a p-type amorphous silicon layer as a second layer of amorphous silicon located on the intrinsic crystalline silicon layer, having a thickness greater than that of the intrinsic crystalline silicon layer, and containing a p-type dopant (e.g., boron).
  • a p-type dopant e.g., boron
  • This heat treatment is a process that diffuses the p-type dopant (e.g., boron) contained in the p-type amorphous silicon layer toward the intrinsic crystalline silicon layer and the silicon oxide film, promoting the crystallization of the amorphous silicon in the p-type amorphous silicon layer.
  • p-type dopant e.g., boron
  • the solar cell element comprises a silicon substrate and a p-type polysilicon layer.
  • the silicon substrate has a first semiconductor region as a first region which is a region of p-type semiconductor as a first conductivity type.
  • the p-type polysilicon layer is a p-type polysilicon layer that is in contact with the silicon substrate and contains a p-type dopant (e.g., boron).
  • the silicon substrate includes a silicon oxide film.
  • the silicon oxide film is an oxide film that is located between the first semiconductor region and the p-type polysilicon layer and is in contact with both the first semiconductor region and the p-type polysilicon layer.
  • the p-type polysilicon layer is a layer formed from the intrinsic crystalline silicon layer and the p-type amorphous silicon layer by performing a heat treatment on the intrinsic crystalline silicon layer as a first layer of intrinsic crystalline silicon located on the silicon oxide film, and the p-type amorphous silicon layer as a second layer of amorphous silicon located on the intrinsic crystalline silicon layer, having a thickness greater than that of the intrinsic crystalline silicon layer, and containing a p-type dopant (e.g., boron).
  • a p-type dopant e.g., boron
  • This heat treatment is a process that progresses the crystallization of the amorphous silicon of the p-type amorphous silicon layer while diffusing the p-type dopant (e.g., boron) contained in the p-type amorphous silicon layer toward the intrinsic crystalline silicon layer and the silicon oxide film.
  • p-type dopant e.g., boron
  • the second peak may be present at a position 3 nm to 10 nm away from the position showing the first peak in the direction from the first semiconductor region through the silicon oxide film toward the oxide film side region.
  • the second peak may be present at a position 3 nm to 8 nm away from the position showing the first peak, or may be present at a position 3 nm to 7 nm away from the position showing the first peak, in the direction from the first semiconductor region through the silicon oxide film toward the oxide film side region.
  • the concentration distribution of the p-type dopant (e.g., boron) in the direction (second direction) from the surface of the p-type polysilicon layer opposite the silicon substrate toward the silicon substrate in the region from the oxide film side region of the silicon oxide film side of the p-type polysilicon layer through the silicon oxide film to the first semiconductor region may be the result of measurement using, for example, SIMS.
  • the oxide film side region may be the region closest to the silicon oxide film among the N regions (N is a natural number equal to or greater than 2) when the p-type polysilicon layer is equally divided into N regions in a direction (second direction) from the surface of the p-type polysilicon layer opposite the silicon substrate toward the silicon substrate.
  • N may be, for example, 2, 3, or any number equal to or greater than 4.
  • the any number equal to or greater than 4 may be 6.
  • the oxide film side region may be a region of the p-type polysilicon layer that is 10 nm or less away from the silicon oxide film.
  • the POLO structure of Structure 4 When the POLO structure of Structure 4 is applied to either the first POLO structure or the second POLO structure, the POLO structure of Structure 4 may be formed by carrying out the following steps 1C to 4C in the order described below.
  • the manufacturing method of a solar cell element may include the following steps 1C, 2C, 3C, and 4C.
  • defects can be reduced in a solar cell element having the POLO structure of Structure 4, which is formed using a p-type amorphous silicon layer as a doped amorphous silicon layer, as in the fourth and fifth embodiments.
  • a silicon oxide film is formed as an oxide film in contact with the first semiconductor region, which is a first region that is an n-type semiconductor region as a first conductivity type, located inside the silicon substrate as a substrate of crystalline silicon and along the surface of the silicon substrate or on the surface of the silicon substrate.
  • Step 2C An intrinsic crystalline silicon layer is formed on the silicon oxide film as the first layer of intrinsic crystalline silicon.
  • a p-type amorphous silicon layer is formed on the intrinsic crystalline silicon layer as a second layer of amorphous silicon having a thickness greater than that of the intrinsic crystalline silicon layer and containing a p-type dopant (e.g., boron) as a second conductivity type different from the first conductivity type.
  • the p-type amorphous silicon layer may be formed, for example, by using a PECVD method.
  • Step 4C A heat treatment is carried out to diffuse the p-type dopant (e.g., boron) contained in the p-type amorphous silicon layer toward the intrinsic crystalline silicon layer and the silicon oxide film while promoting the crystallization of the amorphous silicon of the p-type amorphous silicon layer.
  • a p-type polysilicon layer is generated from the intrinsic crystalline silicon layer and the p-type amorphous silicon layer as a polysilicon layer located on the silicon oxide film and containing a p-type dopant (e.g., boron).
  • the solar cell element may have any of the following configurations 1C, 2C, 5C, and 6C.
  • defects can be reduced in a solar cell element having the POLO structure of the above structure 4 formed using a p-type amorphous silicon layer as a doped amorphous silicon layer, as in the above fourth and fifth embodiments.
  • the solar cell element includes a silicon substrate, a silicon oxide film, and a p-type polysilicon layer.
  • the silicon substrate has a first semiconductor region as a first region, which is a region of n-type semiconductor as a first conductivity type.
  • the silicon oxide film is an oxide film in contact with the first semiconductor region.
  • the p-type polysilicon layer is a p-type polysilicon layer that is in contact with the surface of the silicon oxide film opposite to the first semiconductor region and contains a p-type dopant (e.g., boron) as a second conductivity type different from the first conductivity type.
  • a p-type dopant e.g., boron
  • the p-type polysilicon layer includes a region (oxide film side region) as a second region on the side of the silicon oxide film that is in contact with the silicon oxide film.
  • the distribution of the concentration of the p-type dopant (e.g., boron) in the direction (second direction) from the surface of the p-type polysilicon layer opposite to the silicon substrate toward the silicon substrate has a maximum first peak and a second peak.
  • the second peak is located at a position 3 nm or more away from the position of the first peak in the direction from the first semiconductor region through the silicon oxide film toward the oxide film side region.
  • the solar cell element comprises a silicon substrate and a p-type polysilicon layer.
  • the silicon substrate has a first semiconductor region as a first region which is a region of n-type semiconductor as a first conductivity type.
  • the p-type polysilicon layer is a p-type polysilicon layer that is in contact with the silicon substrate and contains a p-type dopant (e.g., boron) as a second conductivity type different from the first conductivity type.
  • the silicon substrate includes a silicon oxide film.
  • the silicon oxide film is an oxide film that is located between the first semiconductor region and the p-type polysilicon layer and is in contact with both the first semiconductor region and the p-type polysilicon layer.
  • the p-type polysilicon layer includes a region (oxide film side region) as a second region on the side of the silicon oxide film that is in contact with the silicon oxide film.
  • the distribution of the concentration of the p-type dopant e.g., boron
  • the second peak is located at a position 3 nm or more away from the position showing the first peak in the direction from the first semiconductor region through the silicon oxide film toward the oxide film side region.
  • the solar cell element includes a silicon substrate, a silicon oxide film, and a p-type polysilicon layer.
  • the silicon substrate has a first semiconductor region as a first region, which is a region of an n-type semiconductor as a first conductivity type.
  • the silicon oxide film is an oxide film in contact with the first semiconductor region.
  • the p-type polysilicon layer is a p-type polysilicon layer that is in contact with the surface of the silicon oxide film opposite to the first semiconductor region and contains a p-type dopant (e.g., boron) as a second conductivity type different from the first conductivity type.
  • a p-type dopant e.g., boron
  • the p-type polysilicon layer is a layer generated from the intrinsic crystalline silicon layer and the p-type amorphous silicon layer by performing a heat treatment on an intrinsic crystalline silicon layer as a first layer of intrinsic crystalline silicon located on the silicon oxide film, and a p-type amorphous silicon layer as a second layer of amorphous silicon located on the intrinsic crystalline silicon layer, having a thickness greater than that of the intrinsic crystalline silicon layer, and containing a p-type dopant (e.g., boron).
  • a p-type dopant e.g., boron
  • This heat treatment is a process that diffuses the p-type dopant (e.g., boron) contained in the p-type amorphous silicon layer toward the intrinsic crystalline silicon layer and the silicon oxide film, promoting the crystallization of the amorphous silicon in the p-type amorphous silicon layer.
  • p-type dopant e.g., boron
  • the solar cell element comprises a silicon substrate and a p-type polysilicon layer.
  • the silicon substrate has a first semiconductor region as a first region which is a region of n-type semiconductor as a first conductivity type.
  • the p-type polysilicon layer is a p-type polysilicon layer that is in contact with the silicon substrate and contains a p-type dopant (e.g., boron) as a second conductivity type different from the first conductivity type.
  • the silicon substrate includes a silicon oxide film.
  • the silicon oxide film is an oxide film that is located between the first semiconductor region and the p-type polysilicon layer and is in contact with both the first semiconductor region and the p-type polysilicon layer.
  • the p-type polysilicon layer is a layer formed from the intrinsic crystalline silicon layer and the p-type amorphous silicon layer by performing a heat treatment on the intrinsic crystalline silicon layer as a first layer of intrinsic crystalline silicon located on the silicon oxide film, and the p-type amorphous silicon layer as a second layer of amorphous silicon located on the intrinsic crystalline silicon layer, having a thickness greater than that of the intrinsic crystalline silicon layer, and containing a p-type dopant (e.g., boron).
  • a p-type dopant e.g., boron
  • This heat treatment is a process that progresses the crystallization of the amorphous silicon of the p-type amorphous silicon layer while diffusing the p-type dopant (e.g., boron) contained in the p-type amorphous silicon layer toward the intrinsic crystalline silicon layer and the silicon oxide film.
  • p-type dopant e.g., boron
  • the second peak may be present at a position 3 nm to 10 nm away from the position showing the first peak in the direction from the first semiconductor region through the silicon oxide film toward the oxide film side region.
  • the second peak may be present at a position 3 nm to 8 nm away from the position showing the first peak, or may be present at a position 3 nm to 7 nm away from the position showing the first peak, in the direction from the first semiconductor region through the silicon oxide film toward the oxide film side region.
  • the concentration distribution of the p-type dopant (e.g., boron) in the direction (second direction) from the surface of the p-type polysilicon layer opposite the silicon substrate toward the silicon substrate in the region from the oxide film side region of the silicon oxide film side of the p-type polysilicon layer through the silicon oxide film to the first semiconductor region may be a result measured using, for example, SIMS.
  • the oxide film side region may be the region closest to the silicon oxide film among the N regions (N is a natural number equal to or greater than 2) when the p-type polysilicon layer is equally divided into N regions in a direction (second direction) from the surface of the p-type polysilicon layer opposite the silicon substrate toward the silicon substrate.
  • N may be, for example, 2, 3, or any number equal to or greater than 4.
  • the any number equal to or greater than 4 may be 6.
  • the oxide film side region may be a region of the p-type polysilicon layer that is 10 nm or less away from the silicon oxide film.
  • Figure 43 is a cross-sectional view that shows an example of the configuration of a back-contact type solar cell element 1E.
  • the solar cell element 1E has a plate-like shape with a surface (also called the first element surface or front surface) 1f facing the +Z direction and a surface (also called the second element surface or back surface) 1b facing the -Z direction.
  • the solar cell element 1E has a silicon substrate 2E as a substrate.
  • the silicon substrate 2E may be a crystalline silicon substrate.
  • the silicon substrate 2E has a first surface 2f, a second surface 2b on the opposite side to the first surface 2f, and an end surface connecting the first surface 2f and the second surface 2b.
  • the first surface 2f faces in the +Z direction
  • the second surface 2b faces in the -Z direction.
  • the silicon substrate 2E has a first semiconductor region 21A and a second semiconductor region 22E.
  • the second semiconductor region 22E is located inside the silicon substrate 2E and is located in a part of the portion along the second surface 2b, and the first semiconductor region 21A is located in almost the entire area of the silicon substrate 2E except for the second semiconductor region 22E.
  • the second semiconductor region 22E is located, for example, in a plurality of strip-shaped portions each along the +Y direction among the portion located inside the silicon substrate 2E and along the second surface 2b.
  • Each of the first semiconductor region 21A and the second semiconductor region 22E is a p-type semiconductor region containing a p-type dopant as the first conductivity type.
  • a group 13 element such as boron is applied as the p-type dopant.
  • the concentration of the p-type dopant in the second semiconductor region 22E is higher than the concentration of the p-type dopant in the first semiconductor region 21A.
  • a fine uneven structure may be formed on the first surface 2f of the silicon substrate 2E.
  • the solar cell element 1E includes, on the second surface 2b side of the silicon substrate 2E, a silicon oxide film 3E as an oxide film, and an n-type polysilicon layer 4E as a polysilicon layer containing an n-type dopant as a second conductivity type different from the first conductivity type.
  • the silicon oxide film 3E is in contact with the first semiconductor region 21A of the silicon substrate 2E.
  • the silicon oxide film 3E is not in contact with the second semiconductor region 22E.
  • the silicon oxide film 3E is separated from the second semiconductor region 22E.
  • the silicon oxide film 3E is not located in the region along the second semiconductor region 22E on the second surface 2b side of the first semiconductor region 21A.
  • the state in which the silicon oxide film 3E is separated from the second semiconductor region 22E may be achieved, for example, by adjusting the position where the silicon oxide film 3E is formed, or by etching the portion of the silicon substrate 2E on the second surface 2b side.
  • the silicon oxide film 3E may be located on the surface of the silicon substrate 2E on the second surface 2b side, or may be located inside the silicon substrate 2E and in a portion along the second surface 2b.
  • the solar cell element 1E includes the silicon substrate 2E, the silicon oxide film 3E, and the n-type polysilicon layer 4E.
  • the solar cell element 1E includes the silicon substrate 2E including the silicon oxide film 3E and the n-type polysilicon layer 4E.
  • the silicon oxide film 3E is located in a state in which it covers a part of the first semiconductor region 21A from the second surface 2b side.
  • the silicon oxide film 3E is a silicon oxide film.
  • the thickness of the silicon oxide film 3 may be set to, for example, 3 nm or less, or 2 nm or less.
  • the n-type polysilicon layer 4E is in contact with the silicon oxide film 3E.
  • the silicon oxide film 3E is in contact with each of the first semiconductor region 21A and the n-type polysilicon layer 4E.
  • the n-type polysilicon layer 4E is located on the silicon oxide film 3E. More specifically, the n-type polysilicon layer 4E is in contact with the surface of the silicon oxide film 3E opposite to the first semiconductor region 21A.
  • the n-type polysilicon layer 4E is located in a state of covering the surface of the silicon oxide film 3E opposite to the first semiconductor region 21A.
  • the silicon oxide film 3E is located between the first semiconductor region 21A and the n-type polysilicon layer 4E.
  • This n-type polysilicon layer 4E is a layer of polycrystalline silicon doped with an impurity element (doped polysilicon layer).
  • the n-type polysilicon layer 4E contains an n-type dopant as a dopant of a second conductivity type different from the first conductivity type.
  • the n-type polysilicon layer 4E is a layer of n-type polycrystalline silicon.
  • the n-type polysilicon layer 4E is located in a state of covering the silicon oxide film 3E from the opposite side to the first semiconductor region 21A.
  • a group 15 element such as phosphorus is applied as the n-type dopant.
  • the solar cell element 1E may have three first portions P1n, or may have any number of first portions P1n greater than or equal to two.
  • the first portions P1n may be connected to each other, or may not be connected to each other.
  • the thickness direction of the n-type polysilicon layer 4E may be the same as the thickness directions of the silicon substrate 2E and the silicon oxide film 3E, that is, the first thickness direction along the +Z direction, or the second thickness direction along the -Z direction.
  • the thickness of the n-type polysilicon layer 4E is set, for example, in the range of several tens of nm to several hundreds of nm.
  • the thickness of the n-type polysilicon layer 4E may be set in the range of 30 nm to 250 nm.
  • the solar cell element 1E also has a passivation film 7E, a first anti-reflection film 5, a first electrode 6, and a second electrode 9 on the back surface 1b side.
  • the passivation film 7E is located on the n-type polysilicon layer 4E and the first semiconductor region 21A on the back surface 1b of the solar cell element 1E. More specifically, the passivation film 7E is located in a state where it covers almost the entire surface of the n-type polysilicon layer 4E on the side opposite to the silicon oxide film 3E, except for the area where the first electrode 6 is located. Furthermore, the passivation film 7E is located in a state where it covers the surface on the first semiconductor region 21A between the silicon oxide film 3E and the second semiconductor region 22E on the second surface 2b of the silicon substrate 2E. In other words, the passivation film 7E is in contact with the first semiconductor region 21A of the silicon substrate 2E.
  • a layer of aluminum oxide or a layer of silicon oxide is applied to the passivation film 7E.
  • the passivation film 7E has the role of reducing the recombination of minority carriers generated by photoelectric conversion in response to light irradiation in the solar cell element 1E, for example, by inactivating a part of the second surface 2b of the silicon substrate 2 and a part of the surface on the back surface 1b side of the n-type polysilicon layer 4E.
  • the thickness direction of the passivation film 7E may be the direction along the +Z direction as the first thickness direction, like the thickness direction of the silicon substrate 2E, or the direction along the -Z direction as the second thickness direction.
  • the first anti-reflection film 5 is located on the back surface 1b of the solar cell element 1.
  • the first anti-reflection film 5 is located on the passivation film 7E. More specifically, the first anti-reflection film 5 is located in a state where it covers almost the entire surface of the passivation film 7E opposite the silicon substrate 2E, except for the area where the first electrode 6 is located.
  • the first anti-reflection film 5 is, for example, a silicon nitride film.
  • the first anti-reflection film 5 has, for example, a role of protecting the passivation film 7E and a role of reducing the reflection of light on the back surface 1b of the solar cell element 1 together with the passivation film 7E.
  • the thickness direction of the first anti-reflection film 5 may be a direction along the +Z direction as the first thickness direction, as well as the thickness directions of the silicon substrate 2E, the silicon oxide film 3E, and the n-type polysilicon layer 4E, or a direction along the -Z direction as the second thickness direction.
  • the passivation film 7E and the first anti-reflection film 5 serve to separate the p-type second semiconductor region 22E from the n-type polysilicon layer 4E.
  • the first electrode 6 is located on the back surface 1b of the solar cell element 1E.
  • the first electrode 6 has a role of collecting carriers (e.g., electrons) generated by photoelectric conversion in response to light irradiation in the solar cell element 1E on the back surface 1b of the solar cell element 1E and extracting electricity to the outside of the solar cell element 1E.
  • the first electrode 6 is located on the n-type polysilicon layer 4E and is located in a state of penetrating the first anti-reflection film 5 and the passivation film 7E.
  • the first electrode 6 is in contact with the n-type polysilicon layer 4E inside a through hole (also called a third through hole) that penetrates the first anti-reflection film 5 and the passivation film 7E.
  • a through hole also called a third through hole
  • the form in which the first electrode 6 is located on the n-type polysilicon layer 4E may include a form in which the first electrode 6 reaches into a recess located on the first electrode 6 side of the n-type polysilicon layer 4E.
  • the third through-hole may be formed, for example, by a method such as laser beam irradiation or etching using photolithography, or by firing through the first anti-reflection film 5 and the passivation film 7E when the first electrode 6 is formed.
  • the first electrode 6 may have, for example, a plurality of first busbar electrodes each having a longitudinal direction along the +Y direction.
  • the first electrode 6 may further have, for example, a number of first finger electrodes each intersecting with the first busbar electrode for each first busbar electrode.
  • Each of the multiple first finger electrodes has a longitudinal direction along the +X direction and is thinner than the first busbar electrode.
  • the first electrode 6 contains, for example, a metal as a main component.
  • the metal as a main component of the first electrode 6 is, for example, any one of silver, copper, a metal mixture of aluminum and silver, and a metal mixture of titanium, lead, and silver.
  • the second electrode 9 is located on the back surface 1b side of the solar cell element 1E.
  • the second electrode 9 is an electrode for collecting carriers (e.g., holes) generated by photoelectric conversion in response to light irradiation in the solar cell element 1E on the back surface 1b side of the solar cell element 1E and extracting electricity to the outside of the solar cell element 1E.
  • the second electrode 9 is located on the second surface 2b of the second semiconductor region 22E of the silicon substrate 2E and is located in a state of penetrating the first anti-reflection film 5 and the passivation film 7E.
  • the second electrode 9 is in contact with the second surface 2b of the second semiconductor region 22E inside a through hole (also called a fourth through hole) that penetrates the first anti-reflection film 5 and the passivation film 7E.
  • the fourth through hole may be formed, for example, by a method such as irradiation of a laser beam or etching using a photolithography method, or may be formed by firing through the first anti-reflection film 5 and the passivation film 7E when the second electrode 9 is formed.
  • the second electrode 9 may have, for example, multiple second busbar electrodes each having a longitudinal direction along the +Y direction.
  • the second electrode 9 contains, for example, a metal as a main component.
  • the metal as a main component of the second electrode 9 is, for example, any one of silver, copper, a metal mixture of aluminum and silver, and a metal mixture of titanium, lead, and silver.
  • the solar cell element 1E has a passivation film 7 and a second anti-reflection film 8 on the front surface 1f side of the silicon substrate 2.
  • the passivation film 7 is located on the first surface 2f of the silicon substrate 2E. More specifically, the passivation film 7 is located in a state where it covers substantially the entire surface of the first surface 2f of the silicon substrate 2. In other words, the passivation film 7 is in contact with the first semiconductor region 21A of the silicon substrate 2E. For example, an aluminum oxide layer or a silicon oxide layer is applied to the passivation film 7. For example, the passivation film 7 has a role of reducing the recombination of minority carriers generated by photoelectric conversion in response to irradiation of light in the silicon substrate 2E by inactivating the first surface 2f of the silicon substrate 2E.
  • the thickness direction of the passivation film 7 may be the direction along the +Z direction as the first thickness direction, as in the thickness direction of the silicon substrate 2E, or the direction along the -Z direction as the second thickness direction.
  • the second anti-reflection film 8 is located on the front surface 1f of the solar cell element 1E.
  • the second anti-reflection film 8 is located on the passivation film 7. More specifically, the second anti-reflection film 8 is located in a state where it covers almost the entire surface of the passivation film 7 opposite the silicon substrate 2E.
  • the second anti-reflection film 8 is, for example, a silicon nitride film.
  • the second anti-reflection film 8, together with the passivation film 7, serves to reduce the reflectance of light irradiated to the front surface 1f of the solar cell element 1E.
  • the thickness direction of the second anti-reflection film 8 may be the direction along the +Z direction as the first thickness direction, as is the direction of the thickness of the silicon substrate 2E and the passivation film 7, or the direction along the -Z direction as the second thickness direction.
  • the first portion P1n having an example of the POLO structure according to the above structure 2 in the solar cell element 1E having the above configuration can be formed by performing the above steps 1A to 4A in the order described above.
  • the manufacturing method of the solar cell element 1E may have the above steps 1A, 2A, 3A, and 4A.
  • the manufacturing method of the solar cell element 1E may have the following step 1A corresponding to the above step 1A, the following step 2A corresponding to the above step 2A, the following step 3A corresponding to the above step 3A, and the following step 4A corresponding to the above step 4A. This can reduce defects in a solar cell element having the POLO structure of the above structure 2 formed using an n-type amorphous silicon layer as the doped amorphous silicon layer.
  • a silicon oxide film 3E is formed as an oxide film in contact with a first semiconductor region 21A located inside a silicon substrate 2E as a crystalline silicon substrate including a first region 21A that is a region of a p-type semiconductor as a first conductivity type, and along the surface of the silicon substrate 2E or on the surface of the silicon substrate 2E.
  • Step 2A An intrinsic crystalline silicon layer is formed on the silicon oxide film 3E as the first layer of intrinsic crystalline silicon.
  • Step 3A An n-type amorphous silicon layer is formed on the intrinsic crystalline silicon layer as a second layer of amorphous silicon having a thickness greater than that of the intrinsic crystalline silicon layer and containing an n-type dopant (e.g., phosphorus) as a second conductivity type different from the first conductivity type.
  • the n-type amorphous silicon layer may be formed, for example, by using a PECVD method.
  • Step 4A A heat treatment is performed to diffuse the n-type dopant (e.g., phosphorus) contained in the n-type amorphous silicon layer toward the intrinsic crystalline silicon layer and silicon oxide film 3E while promoting the crystallization of the amorphous silicon of the n-type amorphous silicon layer.
  • an n-type polysilicon layer 4E is generated from the intrinsic crystalline silicon layer and the n-type amorphous silicon layer as a polysilicon layer located on the silicon oxide film 3E and containing an n-type dopant (e.g., phosphorus).
  • the solar cell element 1E including the first portion P1n having an example of the POLO structure according to the above structure 2 may have any of the above configurations 1A, 2A, 5A, and 6A.
  • the solar cell element 1E may have any of the following configurations 1A corresponding to the above configuration 1A, 2A corresponding to the above configuration 2A, 5A corresponding to the above configuration 5A, and 6A corresponding to the above configuration 6A. This can reduce defects in a solar cell element having the POLO structure of the above structure 2 formed using an n-type amorphous silicon layer as the doped amorphous silicon layer.
  • Solar cell element 1E comprises silicon substrate 2E, silicon oxide film 3E, and n-type polysilicon layer 4E.
  • Silicon substrate 2E has first semiconductor region 21A as a first region, which is a region of p-type semiconductor as a first conductivity type.
  • Silicon oxide film 3E is an oxide film in contact with first semiconductor region 21A.
  • N-type polysilicon layer 4E is in contact with the surface of silicon oxide film 3E opposite to first semiconductor region 21A, and is an n-type polysilicon layer containing n-type dopant (e.g., phosphorus) as a second conductivity type different from the first conductivity type.
  • n-type dopant e.g., phosphorus
  • N-type polysilicon layer 4E includes region (oxide film side region) 4E1 as a second region on the side of silicon oxide film 3E in contact with silicon oxide film 3E.
  • the distribution of the concentration of the n-type dopant (e.g., phosphorus) in the first thickness direction from the surface of the n-type polysilicon layer 4E opposite the silicon substrate 2E toward the silicon substrate 2E has a maximum first peak and a second peak.
  • the second peak is located at a position 3 nm or more away from the position showing the first peak in the direction from the first semiconductor region 21A through the silicon oxide film 3E toward the oxide film side region 4E1.
  • the solar cell element 1E includes a silicon substrate 2E and an n-type polysilicon layer 4E.
  • the silicon substrate 2E has a first semiconductor region 21A as a first region, which is a region of a p-type semiconductor as a first conductivity type.
  • the n-type polysilicon layer 4E is an n-type polysilicon layer that is in contact with the silicon substrate 2E and contains an n-type dopant (e.g., phosphorus) as a second conductivity type different from the first conductivity type.
  • the silicon substrate 2E includes a silicon oxide film 3E.
  • the silicon oxide film 3E is an oxide film that is located between the first semiconductor region 21A and the n-type polysilicon layer 4E and is in contact with each of the first semiconductor region 21A and the n-type polysilicon layer 4E.
  • the n-type polysilicon layer 4E includes a region (oxide film side region) 4E1 as a second region on the side of the silicon oxide film 3E that is in contact with the silicon oxide film 3E.
  • the distribution of the concentration of the n-type dopant (e.g., phosphorus) in the first thickness direction from the surface of the n-type polysilicon layer 4E opposite the silicon substrate 2E toward the silicon substrate 2E has a maximum first peak and a second peak.
  • the second peak is located at a position 3 nm or more away from the position showing the first peak in the direction from the first semiconductor region 21A through the silicon oxide film 3E toward the oxide film side region 4E1.
  • Solar cell element 1E comprises silicon substrate 2E, silicon oxide film 3E, and n-type polysilicon layer 4E.
  • Silicon substrate 2E has first semiconductor region 21A as a first region which is a region of p-type semiconductor as a first conductivity type.
  • Silicon oxide film 3E is an oxide film in contact with first semiconductor region 21A.
  • n-type polysilicon layer 4E is in contact with the surface of silicon oxide film 3E opposite first semiconductor region 21A and is an n-type polysilicon layer containing an n-type dopant (e.g., phosphorus) as a second conductivity type different from the first conductivity type.
  • n-type dopant e.g., phosphorus
  • the n-type polysilicon layer 4E is a layer formed from the intrinsic crystalline silicon layer and the n-type amorphous silicon layer by performing a heat treatment on the intrinsic crystalline silicon layer as the first layer of intrinsic crystalline silicon located on the silicon oxide film 3E and the n-type amorphous silicon layer as the second layer of amorphous silicon located on the intrinsic crystalline silicon layer, having a thickness greater than that of the intrinsic crystalline silicon layer, and containing an n-type dopant (e.g., phosphorus).
  • an n-type dopant e.g., phosphorus
  • This heat treatment is a process that progresses the crystallization of the amorphous silicon of the n-type amorphous silicon layer while diffusing the n-type dopant (e.g., phosphorus) contained in the n-type amorphous silicon layer toward the intrinsic crystalline silicon layer and the silicon oxide film 3E.
  • n-type dopant e.g., phosphorus
  • Solar cell element 1E comprises silicon substrate 2E and n-type polysilicon layer 4E.
  • Silicon substrate 2E has first semiconductor region 21A as a first region which is a region of p-type semiconductor as a first conductivity type.
  • N-type polysilicon layer 4E is in contact with silicon substrate 2E and is an n-type polysilicon layer containing an n-type dopant (e.g., phosphorus) as a second conductivity type different from the first conductivity type.
  • Silicon substrate 2E includes silicon oxide film 3E.
  • Silicon oxide film 3E is an oxide film located between first semiconductor region 21A and n-type polysilicon layer 4E and in contact with both first semiconductor region 21A and n-type polysilicon layer 4E.
  • the n-type polysilicon layer 4E is a layer formed from the intrinsic crystalline silicon layer and the n-type amorphous silicon layer by performing a heat treatment on the intrinsic crystalline silicon layer as the first layer of intrinsic crystalline silicon located on the silicon oxide film 3E and the n-type amorphous silicon layer as the second layer of amorphous silicon located on the intrinsic crystalline silicon layer, having a thickness greater than that of the intrinsic crystalline silicon layer, and containing an n-type dopant (e.g., phosphorus).
  • an n-type dopant e.g., phosphorus
  • This heat treatment is a process that progresses the crystallization of the amorphous silicon of the n-type amorphous silicon layer while diffusing the n-type dopant (e.g., phosphorus) contained in the n-type amorphous silicon layer toward the intrinsic crystalline silicon layer and the silicon oxide film 3E.
  • n-type dopant e.g., phosphorus
  • the second peak may be present at a position 3 nm to 10 nm away from the position showing the first peak in the direction from the first semiconductor region 21A through the silicon oxide film 3E toward the oxide film side region 4E1.
  • the second peak may be present at a position 3 nm to 8 nm away from the position showing the first peak, or may be present at a position 3 nm to 7 nm away from the position showing the first peak, in the direction from the first semiconductor region 21A through the silicon oxide film 3E toward the oxide film side region 4E1.
  • the concentration distribution of the n-type dopant (e.g., phosphorus) in the first thickness direction as the direction from the surface of the n-type polysilicon layer 4E on the opposite side to the silicon substrate 2E toward the silicon substrate 2E for the region from the oxide film side region 4E1 on the silicon oxide film 3E side of the n-type polysilicon layer 4E through the silicon oxide film 3E to the first semiconductor region 21A may be a result measured using, for example, SIMS.
  • the oxide film side region 4E1 may be the region closest to the silicon oxide film 3E among the N regions (N is a natural number equal to or greater than 2) when the n-type polysilicon layer 4E is equally divided into N regions in the first thickness direction.
  • N may be, for example, two, three, or any number equal to or greater than four.
  • the any number equal to or greater than four may be six.
  • the oxide film side region 4E1 may be a region of the n-type polysilicon layer 4E that is 10 nm or less away from the silicon oxide film 3E.
  • Figure 44 is a cross-sectional view that shows an example of the configuration of another back-contact type solar cell element 1F.
  • the solar cell element 1F is based on the solar cell element 1E illustrated in FIG. 43, but has a configuration in which the silicon substrate 2E is changed to the silicon substrate 2F, the name of the silicon oxide film 3E is changed to the first silicon oxide film 3F1, and the second semiconductor region 22E includes a portion in which the second silicon oxide film 3F2 and the p-type polysilicon layer 10F are stacked.
  • the solar cell element 1F may have two first portions P1n, or may have any number of first portions P1n greater than or equal to two.
  • the first portions P1n may be connected to each other, or may not be connected to each other.
  • the length (also called width) in the X direction of the portion where the second silicon oxide film 3F2 and the p-type polysilicon layer 10F are stacked in the example of FIG. 44 is shown to be greater than the length (also called width) in the X direction of the second semiconductor region 22E in the example of FIG. 43.
  • the silicon substrate 2F is based on the silicon substrate 2E of the solar cell element 1E illustrated in FIG. 43, with the second semiconductor region 22E removed and the first semiconductor region 21A occupying substantially the entire area of the silicon substrate 2F.
  • the solar cell element 1F includes, on the second surface 2b side of the silicon substrate 2F, a second silicon oxide film 3F2 as an oxide film, and a p-type polysilicon layer 10F as a polysilicon layer containing a p-type dopant as a first conductivity type.
  • the second silicon oxide film 3F2 is in contact with the first semiconductor region 21A of the silicon substrate 2F.
  • the second silicon oxide film 3F2 is not in contact with the first silicon oxide film 3F1.
  • the first silicon oxide film 3F1 and the second silicon oxide film 3F2 are located in a form in which they are separated without being in contact with each other.
  • the state in which the first silicon oxide film 3F1 and the second silicon oxide film 3F2 are separated may be realized, for example, by adjusting the position where the first silicon oxide film 3F1 is formed, by adjusting the position where the second silicon oxide film 3F2 is formed, or by etching the oxide film formed on the second surface 2b side of the silicon substrate 2F.
  • the second silicon oxide film 3F2 may be located on the surface on the second surface 2b side of the silicon substrate 2F, or may be located inside the silicon substrate 2F and in a portion along the second surface 2b.
  • the solar cell element 1F when the second silicon oxide film 3F2 is located on the surface of the second surface 2b side of the silicon substrate 2F, the solar cell element 1F includes the silicon substrate 2F, the second silicon oxide film 3F2, and the p-type polysilicon layer 10F.
  • the solar cell element 1F when the second silicon oxide film 3F2 is located inside the silicon substrate 2F and in a portion along the second surface 2b, the solar cell element 1F includes the silicon substrate 2F including the second silicon oxide film 3F2, and the p-type polysilicon layer 10F.
  • the second silicon oxide film 3F2 is located in a state in which it covers a part of the first semiconductor region 21A from the second surface 2b side.
  • the second silicon oxide film 3F2 is a silicon oxide film.
  • the thickness of the second silicon oxide film 3F2 may be set to, for example, 3 nm or less, or 2 nm or less.
  • the p-type polysilicon layer 10F is in contact with the second silicon oxide film 3F2.
  • the second silicon oxide film 3F2 is in contact with each of the first semiconductor region 21A and the p-type polysilicon layer 10F.
  • the p-type polysilicon layer 10F is located on the second silicon oxide film 3F2. More specifically, the p-type polysilicon layer 10F is in contact with the surface of the second silicon oxide film 3F2 opposite to the first semiconductor region 21A.
  • the p-type polysilicon layer 10F is located in a state in which it covers the surface of the second silicon oxide film 3F2 opposite to the first semiconductor region 21A. In the example of FIG.
  • the p-type polysilicon layer 10F is not in contact with the n-type polysilicon layer 4E.
  • the n-type polysilicon layer 4E and the p-type polysilicon layer 10F are located in a form in which they are separated from each other without being in contact with each other.
  • the second silicon oxide film 3F2 is located between the first semiconductor region 21A and the p-type polysilicon layer 10F.
  • This p-type polysilicon layer 10F is a layer of polycrystalline silicon doped with an impurity element (doped polysilicon layer).
  • the p-type polysilicon layer 10F contains a p-type dopant as a first conductive type dopant.
  • the p-type polysilicon layer 10F is a layer of p-type polycrystalline silicon.
  • the p-type polysilicon layer 10F is located in a state of covering the second silicon oxide film 3F2 from the opposite side to the first semiconductor region 21A.
  • a group 13 element such as boron is applied as the p-type dopant.
  • the solar cell element 1F may have two second portions P1p and two second busbar electrodes, or may have any number of second portions P1p (two or more) and any number of second busbar electrodes (two or more).
  • the multiple second portions P1p may be connected to each other, or may not be connected to each other.
  • the thickness direction of the p-type polysilicon layer 10F may be a direction along the +Z direction as the first thickness direction, as with the thickness directions of the silicon substrate 2F and the second silicon oxide film 3F2, or may be a direction along the -Z direction as the second thickness direction.
  • the thickness of the p-type polysilicon layer 10F is set, for example, in the range of several tens of nm to several hundreds of nm.
  • the thickness of the p-type polysilicon layer 10F may be set in the range of 30 nm to 250 nm.
  • the passivation film 7E is located on the back surface 1b of the solar cell element 1E, on the n-type polysilicon layer 4E, on the first semiconductor region 21A, and on the p-type polysilicon layer 10F. More specifically, the passivation film 7E is located in a state in which it covers almost the entire surface of the n-type polysilicon layer 4E on the side opposite the first silicon oxide film 3F1, except for the region where the first electrode 6 is located. The passivation film 7E is located in a state in which it covers the surface on the first semiconductor region 21A between the first silicon oxide film 3F1 and the second silicon oxide film 3F2 on the second surface 2b of the silicon substrate 2F.
  • the passivation film 7E is in contact with the first semiconductor region 21A of the silicon substrate 2F. Furthermore, the passivation film 7E is located in a state in which it covers almost the entire surface of the p-type polysilicon layer 10F on the side opposite the second silicon oxide film 3F2, except for the region where the second electrode 9 is located.
  • the passivation film 7E is, for example, an aluminum oxide layer or a silicon oxide layer.
  • the passivation film 7E has the role of reducing the recombination of minority carriers generated by photoelectric conversion in response to irradiation of light in the solar cell element 1F by inactivating, for example, a part of the second surface 2b of the silicon substrate 2, a part of the surface on the back surface 1b side of the n-type polysilicon layer 4E, and a part of the surface on the back surface 1b side of the p-type polysilicon layer 10F.
  • the passivation film 7E and the first anti-reflection film 5 serve to separate the first silicon oxide film 3F1 from the second silicon oxide film 3F2, and to separate the n-type polysilicon layer 4E from the p-type polysilicon layer 10F.
  • the second electrode 9 is located on the p-type polysilicon layer 10F and is positioned in a state in which it penetrates the first anti-reflection film 5 and the passivation film 7E. In other words, the second electrode 9 is in contact with the p-type polysilicon layer 10F inside the through hole (fourth through hole) that penetrates the first anti-reflection film 5 and the passivation film 7E.
  • the form in which the second electrode 9 is located on the p-type polysilicon layer 10F may include a form in which the second electrode 9 reaches into a recess located on the second electrode 9 side of the p-type polysilicon layer 10F.
  • the second electrode 9 may have, for example, a number of second finger electrodes that cross the second busbar electrode for each second busbar electrode. Each of the number of second finger electrodes has a longitudinal direction along the +X direction and is thinner than the second busbar electrode.
  • the second portion P1p having an example of the POLO structure according to the above structure 3 in the solar cell element 1F having the above configuration can be formed by performing the above steps 1B to 4B in the order described above.
  • the manufacturing method of the solar cell element 1F may include the above steps 1B, 2B, 3B, and 4B.
  • the manufacturing method of the solar cell element 1F may include the following step 1B corresponding to the above step 1B, the following step 2B corresponding to the above step 2B, the following step 3B corresponding to the above step 3B, and the following step 4B corresponding to the above step 4B. This can reduce defects in a solar cell element having the POLO structure of the above structure 3 formed using a p-type amorphous silicon layer as the doped amorphous silicon layer.
  • a second silicon oxide film 3F2 is formed as an oxide film in contact with the first semiconductor region 21A located inside a silicon substrate 2F as a crystalline silicon substrate including a first region 21A that is a region of a p-type semiconductor as a first conductivity type and along the surface of the silicon substrate 2F or on the surface of the silicon substrate 2F.
  • Step 2B An intrinsic crystalline silicon layer is formed on the second silicon oxide film 3F2 as a first layer of intrinsic crystalline silicon.
  • a p-type amorphous silicon layer is formed on the intrinsic crystalline silicon layer as a second layer of amorphous silicon having a thickness greater than that of the intrinsic crystalline silicon layer and containing a p-type dopant (e.g., boron) as the first conductivity type.
  • the p-type amorphous silicon layer may be formed, for example, by using a PECVD method.
  • Step 4B A heat treatment is performed to diffuse the p-type dopant (e.g., boron) contained in the p-type amorphous silicon layer toward the intrinsic crystalline silicon layer and the second silicon oxide film 3F2 while promoting the crystallization of the amorphous silicon of the p-type amorphous silicon layer.
  • a p-type polysilicon layer 10F is generated from the intrinsic crystalline silicon layer and the p-type amorphous silicon layer as a polysilicon layer located on the second silicon oxide film 3F2 and containing a p-type dopant (e.g., boron).
  • the solar cell element 1F including the second portion P1p having an example of the POLO structure according to the above structure 3 may have any one of the above configurations 1B, 2B, 5B, and 6B.
  • the solar cell element 1F may have any one of the following configurations 1B corresponding to the above configuration 1B, 2B corresponding to the above configuration 2B, 5B corresponding to the above configuration 5B, and 6B corresponding to the above configuration 6B. This can reduce defects in a solar cell element having the POLO structure of the above structure 3 formed using a p-type amorphous silicon layer as the doped amorphous silicon layer.
  • the solar cell element 1F comprises a silicon substrate 2F, a second silicon oxide film 3F2, and a p-type polysilicon layer 10F.
  • the silicon substrate 2F has a first semiconductor region 21A as a first region, which is a region of a p-type semiconductor as a first conductivity type.
  • the second silicon oxide film 3F2 is an oxide film in contact with the first semiconductor region 21A.
  • the p-type polysilicon layer 10F is in contact with the surface of the second silicon oxide film 3F2 opposite to the first semiconductor region 21A and is a p-type polysilicon layer containing a p-type dopant (e.g., boron) as a first conductivity type.
  • a p-type dopant e.g., boron
  • the p-type polysilicon layer 10F includes a region (oxide film side region) 10F1 as a second region on the side of the second silicon oxide film 3F2 that is in contact with the second silicon oxide film 3F2.
  • the distribution of the concentration of the p-type dopant (e.g., boron) in the first thickness direction from the surface of the p-type polysilicon layer 10F opposite the silicon substrate 2F toward the silicon substrate 2F has a maximum first peak and a second peak.
  • the second peak is located at a position 3 nm or more away from the position showing the first peak in the direction from the first semiconductor region 21A through the second silicon oxide film 3F2 toward the oxide film side region 10F1.
  • the solar cell element 1F includes a silicon substrate 2F and a p-type polysilicon layer 10F.
  • the silicon substrate 2F has a first semiconductor region 21A as a first region, which is a region of a p-type semiconductor as a first conductivity type.
  • the p-type polysilicon layer 10F is a p-type polysilicon layer that is in contact with the silicon substrate 2F and contains a p-type dopant (e.g., boron) as a first conductivity type.
  • the silicon substrate 2F includes a second silicon oxide film 3F2.
  • the second silicon oxide film 3F2 is an oxide film that is located between the first semiconductor region 21A and the p-type polysilicon layer 10F and is in contact with each of the first semiconductor region 21A and the p-type polysilicon layer 10F.
  • the p-type polysilicon layer 10F includes a region (oxide film side region) 10F1 as a second region on the side of the second silicon oxide film 3F2 that is in contact with the second silicon oxide film 3F2.
  • the distribution of the concentration of the p-type dopant (e.g., boron) in the first thickness direction from the surface of the p-type polysilicon layer 10F opposite the silicon substrate 2F toward the silicon substrate 2F has a maximum first peak and a second peak.
  • the second peak is located at a position 3 nm or more away from the position showing the first peak in the direction from the first semiconductor region 21A through the second silicon oxide film 3F2 toward the oxide film side region 10F1.
  • Solar cell element 1F comprises a silicon substrate 2F, a second silicon oxide film 3F2, and a p-type polysilicon layer 10F.
  • Silicon substrate 2F has a first semiconductor region 21A as a first region which is a region of p-type semiconductor as a first conductivity type.
  • Second silicon oxide film 3F2 is an oxide film in contact with first semiconductor region 21A.
  • P-type polysilicon layer 10F is in contact with the surface of second silicon oxide film 3F2 opposite to first semiconductor region 21A and is a p-type polysilicon layer containing a p-type dopant (e.g., boron) as a first conductivity type.
  • a p-type dopant e.g., boron
  • the p-type polysilicon layer 10F is a layer formed from the intrinsic crystalline silicon layer and the p-type amorphous silicon layer by performing a heat treatment on the intrinsic crystalline silicon layer as the first layer of intrinsic crystalline silicon located on the second silicon oxide film 3F2 and the p-type amorphous silicon layer as the second layer of amorphous silicon located on the intrinsic crystalline silicon layer, having a thickness greater than that of the intrinsic crystalline silicon layer, and containing a p-type dopant (e.g., boron).
  • a p-type dopant e.g., boron
  • This heat treatment is a process that progresses the crystallization of the amorphous silicon of the p-type amorphous silicon layer while diffusing the p-type dopant (e.g., boron) contained in the p-type amorphous silicon layer toward the intrinsic crystalline silicon layer and the second silicon oxide film 3F2.
  • the p-type dopant e.g., boron
  • the solar cell element 1F comprises a silicon substrate 2F and a p-type polysilicon layer 10F.
  • the silicon substrate 2F has a first semiconductor region 21A as a first region which is a region of a p-type semiconductor as a first conductivity type.
  • the p-type polysilicon layer 10F is a p-type polysilicon layer that is in contact with the silicon substrate 2F and contains a p-type dopant (e.g., boron) as a first conductivity type.
  • the silicon substrate 2F includes a second silicon oxide film 3F2.
  • the second silicon oxide film 3F2 is an oxide film that is located between the first semiconductor region 21A and the p-type polysilicon layer 10F and is in contact with both the first semiconductor region 21A and the p-type polysilicon layer 10F.
  • the p-type polysilicon layer 10F is a layer formed from the intrinsic crystalline silicon layer and the p-type amorphous silicon layer by performing a heat treatment on the intrinsic crystalline silicon layer as the first layer of intrinsic crystalline silicon located on the second silicon oxide film 3F2 and the p-type amorphous silicon layer as the second layer of amorphous silicon located on the intrinsic crystalline silicon layer, having a thickness greater than that of the intrinsic crystalline silicon layer, and containing a p-type dopant (e.g., boron).
  • a p-type dopant e.g., boron
  • This heat treatment is a process that progresses the crystallization of the amorphous silicon of the p-type amorphous silicon layer while diffusing the p-type dopant (e.g., boron) contained in the p-type amorphous silicon layer toward the intrinsic crystalline silicon layer and the second silicon oxide film 3F2.
  • the p-type dopant e.g., boron
  • the second peak may be located at a position 3 nm to 10 nm away from the position showing the first peak in the direction from the first semiconductor region 21A through the second silicon oxide film 3F2 toward the oxide film side region 10F1.
  • the second peak may be located at a position 3 nm to 8 nm away from the position showing the first peak, or may be located at a position 3 nm to 7 nm away from the position showing the first peak, in the direction from the first semiconductor region 21A through the second silicon oxide film 3F2 toward the oxide film side region 10F1.
  • the distribution of the concentration of p-type dopant (e.g., boron) in the first thickness direction, which is the direction from the surface of the p-type polysilicon layer 10F opposite the silicon substrate 2F toward the silicon substrate 2F, in the region from the oxide film side region 10F1 on the second silicon oxide film 3F2 side of the p-type polysilicon layer 10F through the second silicon oxide film 3F2 to the first semiconductor region 21A, may be the result of measurement using, for example, SIMS.
  • the oxide film side region 10F1 may be the region closest to the second silicon oxide film 3F2 among the N regions.
  • N may be, for example, two, three, or any number equal to or greater than four.
  • the any number equal to or greater than four may be six.
  • the oxide film side region 10F1 may be a region of the p-type polysilicon layer 10F that is 10 nm or less away from the second silicon oxide film 3F2.
  • a specific example in which the concentration distribution of a specific n-type dopant (e.g., phosphorus) in a first direction of a sample related to a POLO structure and the concentration distribution of a specific p-type dopant (e.g., boron) in a second direction of a sample related to a POLO structure are measured using SIMS, but this is not limited to the above.
  • a specific example in which the concentration distribution of a dopant measured using SIMS is used is given, but this is not limited to the above.
  • SIMS multiple discrete positions in the first direction of a sample are targeted, and the concentration of a specific n-type dopant is measured in sequence, so long as data on the concentration distribution of a specific n-type dopant in the first direction of a sample can be obtained, an analysis method other than SIMS may be adopted. Also, for example, as with SIMS, if data on the distribution of the concentration of a specific p-type dopant in the second direction of a sample can be obtained by sequentially measuring the concentration of a specific p-type dopant at multiple discrete positions in the second direction of a sample, other analysis methods other than SIMS may be used.
  • the distribution of the dopant concentration measured using an analysis method other than SIMS may be used instead of the distribution of the dopant concentration measured using SIMS.
  • the other analysis method for example, a three-dimensional atom probe method or the like may be used.

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Abstract

Un élément de batterie solaire (1) est équipé d'un substrat (2), d'un film d'oxyde (3) et d'une couche de polysilicium (4). Le substrat (2) présente une première région (21) qui est une région semi-conductrice d'un premier type de conductivité. Le film d'oxyde (3) est en contact avec la première région (21). La couche de polysilicium (4) est en contact avec une surface du film d'oxyde (3) sur le côté opposé à la première région (21). La couche de polysilicium (4) contient un dopant. La couche de polysilicium (4) comprend une seconde région (41). La seconde région (41) est une région côté film d'oxyde de la couche de polysilicium (4) en contact avec le film d'oxyde (3). Dans une région allant de la seconde région (41) à la première région (21) à travers le film d'oxyde (3), la distribution de la concentration de dopant dans la couche de polysilicium (4) dans une direction allant d'une surface sur le côté opposé au substrat (2) vers le substrat (2) présente un premier pic maximal (Pk1) et un second pic maximal (Pk2). Dans la distribution de la concentration de dopant, le second pic (Pk2) se situe à une distance d'au moins 3 nm à partir d'une position indiquant le premier pic (Pk1) dans une direction allant de la première région (21) à la seconde région (41) à travers le film d'oxyde (3). Le dopant est du premier type de conductivité ou d'un second type de conductivité différent du premier type de conductivité.
PCT/JP2024/022041 2023-06-20 2024-06-18 Élément de batterie solaire et procédé de fabrication d'élément de batterie solaire Pending WO2024262492A1 (fr)

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Citations (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2017017323A (ja) * 2015-06-30 2017-01-19 エルジー エレクトロニクス インコーポレイティド 太陽電池及びその製造方法
JP2017135386A (ja) * 2016-01-29 2017-08-03 エルジー エレクトロニクス インコーポレイティド 太陽電池の製造方法
WO2017145633A1 (fr) * 2016-02-22 2017-08-31 パナソニックＩｐマネジメント株式会社 Élément de batterie solaire et procédé de fabrication d'élément de batterie solaire
US20180226521A1 (en) * 2017-02-06 2018-08-09 Alliance For Sustainable Energy, Llc Doped passivated contacts
WO2019021545A1 (fr) * 2017-07-28 2019-01-31 三菱電機株式会社 Photopile et son procédé de fabrication
US20200279970A1 (en) * 2017-02-10 2020-09-03 Tempress Ip B.V. Method of Manufacturing a Passivated Solar Cell and Resulting Passivated Solar Cell
JP2021516873A (ja) * 2018-11-27 2021-07-08 チンアオ ソーラー カンパニー リミテッド 結晶シリコン太陽電池及びその製造方法、太陽光発電モジュール
JP7148753B1 (ja) * 2022-04-11 2022-10-05 ジョジアン ジンコ ソーラー カンパニー リミテッド 太陽電池、光起電力モジュールおよび太陽電池の製造方法

Patent Citations (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2017017323A (ja) * 2015-06-30 2017-01-19 エルジー エレクトロニクス インコーポレイティド 太陽電池及びその製造方法
JP2017135386A (ja) * 2016-01-29 2017-08-03 エルジー エレクトロニクス インコーポレイティド 太陽電池の製造方法
WO2017145633A1 (fr) * 2016-02-22 2017-08-31 パナソニックＩｐマネジメント株式会社 Élément de batterie solaire et procédé de fabrication d'élément de batterie solaire
US20180226521A1 (en) * 2017-02-06 2018-08-09 Alliance For Sustainable Energy, Llc Doped passivated contacts
US20200279970A1 (en) * 2017-02-10 2020-09-03 Tempress Ip B.V. Method of Manufacturing a Passivated Solar Cell and Resulting Passivated Solar Cell
WO2019021545A1 (fr) * 2017-07-28 2019-01-31 三菱電機株式会社 Photopile et son procédé de fabrication
JP2021516873A (ja) * 2018-11-27 2021-07-08 チンアオ ソーラー カンパニー リミテッド 結晶シリコン太陽電池及びその製造方法、太陽光発電モジュール
JP7148753B1 (ja) * 2022-04-11 2022-10-05 ジョジアン ジンコ ソーラー カンパニー リミテッド 太陽電池、光起電力モジュールおよび太陽電池の製造方法

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
BAEK, JONG-HOON ET AL.: "Passivation improvement of nitric acid oxide by ozone post-treatment for tunnel oxide passivated contacts silicon solar cells", APPLIED SURFACE SCIENCE, vol. 489, 2019, pages 330 - 335, XP085737987, DOI: 10.1016/j.apsusc.2019.05.369 *

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