WO2014112053A1 - Solar cell and method for manufacturing same - Google Patents

Abstract

This solar cell is provided with: a semiconductor substrate (2) of a first conductivity type, which has, on one surface, an n-type impurity diffusion layer (3) wherein an impurity element of a second conductivity type is diffused; a light receiving surface-side electrode (12) which is formed on the one surface side of the semiconductor substrate (2) and is electrically connected to the n-type impurity diffusion layer (3); a back-side silver sputtering film (8) which is formed on a region of the other surface of the semiconductor substrate (2), has a light reflectance higher than an aluminum electrode that is formed from an aluminum paste, and reflects the light transmitted through the semiconductor substrate (2) from the one surface of the semiconductor substrate (2); and a conductive film (22) which serves as a connection layer for connecting a tab wire that electrically connects the other surface of the semiconductor substrate (2) and another solar cell (1) with each other, and which is bonded to a region of the other surface of the semiconductor substrate (2), said region being the region other than the back-side silver sputtering film (8).

Description

Solar cell and manufacturing method thereof

The present invention relates to a solar battery cell and a manufacturing method thereof.

Conventional bulk silicon solar cells (hereinafter sometimes referred to as solar cells) are generally manufactured by the following method. First, for example, a p-type silicon substrate is prepared as a first conductivity type substrate. Then, the damaged layer on the silicon surface generated when the silicon substrate is sliced from the cast ingot is removed with a thickness of 10 μm to 20 μm with an alkaline solution such as sodium hydroxide or potassium hydroxide of several wt% to 20 wt%, for example.

Next, a surface uneven structure called texture is formed on the surface from which the damage layer has been removed. On the surface side (light-receiving surface side) of the solar battery cell, such a texture is usually formed in order to suppress light reflection and capture as much sunlight as possible onto the p-type silicon substrate. As a method for producing the texture, for example, there is a method called an alkali texture method. In the alkaline texture method, anisotropic etching is performed with a solution in which an additive that promotes anisotropic etching such as IPA (isopropyl alcohol) is added to a low concentration alkali solution such as sodium hydroxide or potassium hydroxide of several wt%. Then, the texture is formed so that the silicon (111) surface appears.

Subsequently, as a diffusion treatment, the p-type silicon substrate is treated for several tens of minutes at, for example, 800 ° C. to 900 ° C. in a mixed gas atmosphere of, for example, phosphorus oxychloride (POCl ₃ ), nitrogen, and oxygen, and the second surface is uniformly applied to the entire surface. An n-type layer is formed as a conductive impurity layer. By setting the sheet resistance of the n-type layer uniformly formed on the silicon surface to about 30 to 80 Ω / □, good electric characteristics of the solar cell can be obtained.

Here, since the n-type layer is uniformly formed on the silicon surface, the front surface and the back surface are in an electrically connected state. In order to cut off this electrical connection, the end face region of the p-type silicon substrate is etched by dry etching, for example. As another method, end face separation of the p-type silicon substrate may be performed by a laser. Thereafter, the p-type silicon substrate is immersed in a hydrofluoric acid aqueous solution, and the glassy material (PSG) deposited on the surface during the diffusion treatment is removed by etching.

Next, an insulating film such as a silicon oxide film, a silicon nitride film, or a titanium oxide film is formed with a uniform thickness on the surface of the n-type layer as an insulating film (antireflection film) for the purpose of preventing reflection. In the case of forming a silicon nitride film as the antireflection film, for example, it is formed by plasma CVD using silane (SiH ₄ ) gas and ammonia (NH ₃ ) gas as raw materials under conditions of 300 ° C. or higher and reduced pressure. The refractive index of the antireflection film is about 2.0 to 2.2, and the optimum film thickness is about 70 nm to 90 nm. It should be noted that the antireflection film formed in this way is an insulator, and merely forming the surface-side electrode thereon does not act as a solar cell.

Next, using a grid electrode forming mask and a bus electrode forming mask, a silver paste to be a surface side electrode is applied to the shape of the grid electrode and the bus electrode on the antireflection film by a screen printing method and dried. Here, the silver paste for the surface-side electrode is formed on an insulating film for the purpose of preventing reflection.

Next, the back aluminum electrode paste containing aluminum, glass, etc., which becomes the back aluminum electrode, and the back silver paste which becomes the back silver bus electrode are screen-printed into the shape of the back aluminum electrode and the shape of the back silver bus electrode on the back surface of the substrate, respectively. Apply and dry.

Next, the electrode paste applied to the front and back surfaces of the silicon substrate is simultaneously fired at about 600 ° C. to 900 ° C. for several minutes to several tens of seconds. As a result, a grid electrode and a bus electrode are formed on the front surface side of the silicon substrate as surface side electrodes, and a back aluminum electrode and a back silver bus electrode are formed on the back surface side of the silicon substrate as back surface side electrodes. Here, on the surface side of the silicon substrate, the silver material comes into contact with silicon and re-solidifies while the antireflection film is melted with the glass material contained in the silver paste. Thereby, electrical connection between the surface side electrode and the silicon substrate (n-type layer) is ensured. Such a process is called a fire-through method. Further, the back aluminum electrode paste also reacts with the back surface of the silicon substrate to compensate for the n-type layer formed by diffusion immediately below the back aluminum electrode, thereby forming a P + layer. By carrying out such a process, a bulk type silicon solar battery cell is formed.

And in the module process, after applying the flux to the location where the tab wires for electrically connecting the solar cells are attached, heat at 200 ° C. or higher is applied to the solar cells and the soldered tab wires, A plurality of solar cells are electrically connected by bonding tab wires. Here, the solder cannot be directly connected to the aluminum electrode. For this reason, the back silver electrode, the soldered tab wire, and the flux are required for the tab wire connection on the back surface side of the silicon substrate in the normal module process.

On the other hand, recently, a technology has been proposed in which an aluminum electrode is formed on the entire surface using paste and the tab wire is directly bonded to the silicon on the back surface of the solar cell without the back silver electrode by using a conductive film without using solder. (For example, see Non-Patent Document 1). According to this technology, a silver electrode is not required on the back surface of the solar battery cell, and the solar battery cell and the tab wire can be electrically and mechanically connected at a low temperature of 200 ° C. or less like a double-sided tape. It becomes.

R. Kopecek, et al. “INDUSTRIAL LARGE AREA N-TYPE SOLAR CELLS WITH ALUMINUM REAR EMITTER WITH STABLE EFFICIENCIES” Photovoltaic Specialists Conference (PVSC), 2010 35th IEEE 1423-1426

However, in the above-described conventional technology, the aluminum electrode formed using the aluminum paste has low light reflectance, and light incident on the light receiving surface side, transmitted through the solar cell, and reached the back surface of the solar cell. Low reflectivity. As a result, there has been a problem that the light reaching the back surface of the solar battery cell cannot be effectively used, and the photoelectric conversion efficiency cannot be improved by light reflection on the back surface.

The present invention has been made in view of the above, and is a solar cell in which the connection of a tab wire to an electrode is easy and the photoelectric conversion efficiency is improved by light reflection on the back surface, and a method for manufacturing the solar cell. The purpose is to obtain.

In order to solve the above-described problems and achieve the object, a solar battery cell according to the present invention includes a first conductivity type semiconductor substrate having an impurity diffusion layer in which a second conductivity type impurity element is diffused on one surface side. A light receiving surface side electrode electrically connected to the impurity diffusion layer and formed on one surface side of the semiconductor substrate, and a light reflectance higher than that of an aluminum electrode formed of an aluminum paste, and the other surface of the semiconductor substrate A light reflection layer that is formed in a partial region on the side and reflects light transmitted through the semiconductor substrate from one surface side of the semiconductor substrate; electrically connects the other surface side of the semiconductor substrate and other solar cells. A conductive film that is a connection layer for connecting tab wires to be connected to each other and that is attached on a region excluding the light reflection layer on the other surface side of the semiconductor substrate.

According to the present invention, there is an effect that it is possible to obtain a solar cell in which the tab wire can be easily connected to the electrode and the photoelectric conversion efficiency is improved by the light reflection on the back surface.

FIG. 1-1 is a diagram schematically showing the configuration of the solar battery cell according to the first embodiment of the present invention. FIG. 1-2 is a diagram schematically showing the configuration of the solar battery cell according to the first embodiment of the present invention. FIG. 1-3 is a diagram schematically showing a configuration of the solar battery cell according to the first embodiment of the present invention. FIG. 1-4 is a diagram schematically showing the configuration of the solar battery cell according to the first embodiment of the present invention. FIG. 1-5 is a diagram schematically illustrating the configuration of the solar battery cell according to the first embodiment of the present invention. FIG. 2 is a flowchart for explaining an example of the manufacturing process of the solar battery cell according to the embodiment of the present invention and a method of connecting a tab to the back surface of the solar battery cell. FIGS. 3-1 is process drawing which shows typically an example of the manufacturing process of the photovoltaic cell concerning Embodiment 1 of this invention. FIGS. FIGS. 3-2 is process drawing which shows typically an example of the manufacturing process of the photovoltaic cell concerning Embodiment 1 of this invention. FIGS. FIGS. 3-3 is process drawing which shows typically an example of the manufacturing process of the photovoltaic cell concerning Embodiment 1 of this invention. FIGS. FIGS. 3-4 is process drawing which shows typically an example of the manufacturing process of the photovoltaic cell concerning Embodiment 1 of this invention. FIGS. FIGS. 3-5 is process drawing which shows typically an example of the manufacturing process of the photovoltaic cell concerning Embodiment 1 of this invention. FIGS. FIGS. 3-6 is process drawing which shows typically an example of the manufacturing process of the photovoltaic cell concerning Embodiment 1 of this invention. FIGS. FIGS. 3-7 is process drawing which shows typically an example of the manufacturing process of the photovoltaic cell concerning Embodiment 1 of this invention. FIGS. FIGS. 3-8 is process drawing which shows typically an example of the manufacturing process of the photovoltaic cell concerning Embodiment 1 of this invention. FIGS. FIGS. 3-9 is process drawing which shows typically an example of the manufacturing process of the photovoltaic cell concerning Embodiment 1 of this invention. FIGS. FIGS. 3-10 is process drawing which shows typically an example of the manufacturing process of the photovoltaic cell concerning Embodiment 1 of this invention. FIGS. FIGS. 3-11 is process drawing which shows typically an example of the manufacturing process of the photovoltaic cell concerning Embodiment 1 of this invention. FIGS. FIG. 3-12 is a process diagram schematically showing an example of the manufacturing process of the solar battery cell according to the first embodiment of the present invention. FIGS. 3-13 is process drawing which shows typically an example of the manufacturing process of the photovoltaic cell concerning Embodiment 1 of this invention. FIGS. FIG. 4A is a process diagram schematically showing a process of connecting a tab to the back surface of the solar battery cell in the module process. FIG. 4-2 is a process diagram schematically showing a process of connecting the tab to the back surface of the solar battery cell in the module process. FIG. 4-3 is a process diagram schematically showing a process of connecting the tab to the back surface of the solar battery cell in the module process. FIG. 4-4 is a process diagram schematically showing a process of connecting the tab to the back surface of the solar battery cell in the module process. FIG. 4-5 is a process diagram schematically showing a process of connecting the tab to the back surface of the solar battery cell in the module process. FIG. 5-1 is a top view schematically showing an aluminum foil with a conductive film according to the second embodiment of the present invention. FIG. 5-2 is a cross-sectional view schematically showing the aluminum foil with a conductive film according to the second embodiment of the present invention, and is a cross-sectional view of the main part in the CC direction of FIG. FIG. 6-1 is a process diagram schematically illustrating a process of connecting a tab to the back surface of the solar battery cell when using the aluminum foil with a conductive film according to the second embodiment of the present invention. FIG. 6-2 is a process diagram schematically showing a process of connecting a tab to the back surface of the solar battery cell when using the aluminum foil with a conductive film according to the second embodiment of the present invention. FIG. 7-1 is a bottom view of the semiconductor substrate schematically showing the method for forming the high light reflection film according to the third embodiment of the present invention. FIG. 7-2 is a bottom view of the semiconductor substrate schematically showing the method for forming the high light reflection film according to the third embodiment of the present invention. FIG. 7-3 is a bottom view of the semiconductor substrate schematically showing the method for forming the high light reflection film according to the third embodiment of the present invention. FIG. 7-4 is a bottom view of the semiconductor substrate schematically showing the method for forming the high light reflection film according to the third embodiment of the present invention. FIGS. 8-1 is sectional drawing which shows typically the manufacturing method of the photovoltaic cell concerning Embodiment 4 of this invention. FIGS. FIGS. 8-2 is sectional drawing which shows typically the manufacturing method of the photovoltaic cell concerning Embodiment 4 of this invention. FIGS.

Hereinafter, embodiments of a solar battery cell and a manufacturing method thereof according to the present invention will be described in detail with reference to the drawings. In addition, this invention is not limited to the following description, In the range which does not deviate from the summary of this invention, it can change suitably. In the drawings shown below, the scale of each member may be different from the actual scale for easy understanding. The same applies between the drawings. Further, even a plan view may be hatched to make the drawing easy to see.

Embodiment 1 FIG.
FIGS. 1-1 to 1-5 are diagrams schematically showing the configuration of the solar battery cell 1 according to the first embodiment of the present invention. FIG. 1-1 is a top view of the solar battery cell 1 viewed from the light receiving surface side. FIG. 1-2 is a bottom view of the solar battery cell 1 as viewed from the side opposite to the light receiving surface (back surface). 1-3 is a cross-sectional view of the main part of the solar battery cell 1, and is a cross-sectional view of the main part in the AA direction of FIGS. 1-1 and 1-2. 1-4 is a cross-sectional view of the main part of the solar battery cell 1, and is a cross-sectional view of the main part in the BB direction of FIGS. 1-1 and 1-2. FIG. 1-5 shows the sun as viewed from the side opposite to the light receiving surface (back surface) in a state where the conductive film 22 which is a connection layer for connecting tab wires for electrically connecting the solar cells is attached. 2 is a bottom view of the battery cell 1. FIG. The solar battery cell 1 is a silicon solar battery used for home use or the like.

In the solar cell 1 according to the present embodiment, an n-type impurity diffusion layer 3 is formed by phosphorous diffusion on the light receiving surface side of a semiconductor substrate 2 made of p-type single crystal silicon, and a semiconductor substrate 11 having a pn junction is formed. In addition, an antireflection film 4 made of a silicon nitride film (SiN film) is formed on the n-type impurity diffusion layer 3. The semiconductor substrate 2 is not limited to a p-type single crystal silicon substrate, and an n-type single crystal silicon substrate may be used.

Also, as shown in FIGS. 1-4, a texture structure composed of minute irregularities 2a is formed on the light receiving surface side (n-type impurity diffusion layer 3) and the back surface side of the semiconductor substrate 11. The texture structure increases the area for absorbing light from the outside on the light receiving surface, suppresses the light reflectance on the light receiving surface, and confines light.

The antireflection film 4 is made of an insulating film for the purpose of preventing reflection, such as a silicon nitride film (SiN film), a silicon oxide film (SiO ₂ film), or a titanium oxide film (TiO ₂ ) film. In addition, a plurality of long and narrow surface silver grid electrodes 5 are provided side by side on the light receiving surface side of the semiconductor substrate 11, and a surface silver bus electrode 6 electrically connected to the surface silver grid electrode 5 is substantially the same as the surface silver grid electrode 5. They are provided so as to be orthogonal to each other, and are respectively electrically connected to the n-type impurity diffusion layer 3 at the bottom portion. The front silver grid electrode 5 and the front silver bus electrode 6 are made of a silver material.

The front silver grid electrode 5 has a width of about 100 μm to 200 μm, for example, and is arranged substantially in parallel at intervals of about 2 mm, and collects electricity generated inside the semiconductor substrate 11. Further, the front silver bus electrodes 6 have a width of, for example, about 1 mm to 3 mm and are arranged in a number of 2 to 4 per solar battery cell, and the electricity collected by the front silver grid electrode 5 is taken out to the outside. The front silver grid electrode 5 and the front silver bus electrode 6 constitute a light receiving surface side electrode 12 as a first electrode. Since the light receiving surface side electrode 12 blocks sunlight incident on the semiconductor substrate 11, it is desirable to reduce the area as much as possible from the viewpoint of improving the power generation efficiency, and a comb-shaped surface as shown in FIG. In general, the silver grid electrode 5 and the bar-shaped front silver bus electrode 6 are arranged.

For the electrode material of the light receiving surface side electrode of the silicon solar battery cell, a silver paste is usually used, for example, lead boron glass is added. This glass has a frit shape and is composed of, for example, lead (Pb) 5-30 wt%, boron (B) 5-10 wt%, silicon (Si) 5-15 wt%, and oxygen (O) 30-60 wt%. Furthermore, zinc (Zn), cadmium (Cd), etc. may be mixed by several wt%. Such lead boron glass has a property of melting by heating at several hundred degrees C. (for example, 800.degree. C.) and eroding silicon at that time. In general, in a method for manufacturing a crystalline silicon solar battery cell, a method of obtaining electrical contact between a silicon substrate and a silver paste by using the characteristics of the glass frit is used.

On the other hand, a back surface passivation film 7, which is a back surface insulating film made of a silicon nitride film (SiN film), is formed on the entire back surface (surface opposite to the light receiving surface) of the semiconductor substrate 11, and high light is applied on the back surface passivation film 7. A back silver sputtering film 8 which is a reflective film is provided. A back aluminum electrode 9, which is a second electrode made of an aluminum material, is provided surrounded by the back surface passivation film 7 and the back silver sputtering film 8. The back aluminum electrode 9 has a comb shape like the light receiving surface side of the semiconductor substrate 11 so that current collection from the back surface of the semiconductor substrate 11 can be efficiently performed. The intersection part is formed in a substantially square shape. The square portions are arranged in substantially the same direction as the front silver bus electrode 6. Since the back silver sputtering film 8 is disposed over the entire back surface of the semiconductor substrate 11, even when the electrode pattern of the back aluminum electrode 9 is broken, electricity can be collected and also has a role of assisting the electrode. . As shown in FIG. 1-5, tab wires 21 made of a conductive material for electrically connecting the solar cells 1 to each other are connected to the back aluminum electrode 9 in the module process.

In addition, a P + layer (BSF (Back Surface Field) layer) 10 containing a high concentration impurity is formed in a lower region of the back aluminum electrode 9 in the surface layer portion on the back surface (surface opposite to the light receiving surface) of the semiconductor substrate 11. Is formed. The P + layer 10 is provided to obtain the BSF effect, and the electron concentration of the p-type layer (semiconductor substrate 2) is increased by an electric field having a band structure so that electrons in the p-type layer (semiconductor substrate 2) do not disappear. .

In the solar cell 1 configured as described above, sunlight is applied to the pn junction surface (the junction surface between the semiconductor substrate 2 and the n-type impurity diffusion layer 3) of the semiconductor substrate 11 from the light receiving surface side of the solar cell 1. Then, holes and electrons are generated. The generated electrons move toward the n-type impurity diffusion layer 3 and the holes move toward the P + layer 10 due to the electric field at the pn junction. As a result, the number of electrons in the n-type impurity diffusion layer 3 becomes excessive and the number of holes in the P + layer 10 becomes excessive. As a result, photovoltaic power is generated. This photovoltaic power is generated in the direction of biasing the pn junction in the forward direction, the light receiving surface side electrode 12 connected to the n-type impurity diffusion layer 3 becomes a negative pole, and the back aluminum electrode 9 connected to the P + layer 10 becomes a positive pole. Thus, a current flows through an external circuit (not shown).

Hereinafter, the manufacturing method of the photovoltaic cell 1 according to the present embodiment will be described with reference to the drawings. FIG. 2 is a flowchart for explaining an example of the manufacturing process of solar cell 1 according to the embodiment of the present invention and a method of connecting tab wire 21 to the back surface of solar cell 1. FIGS. 3-1 to 3-13 are process diagrams schematically showing an example of the manufacturing process of the solar battery cell 1 according to the first embodiment of the present invention. FIGS. 3-1 to 3-6 are cross-sectional views of relevant parts corresponding to the AA and BB directions in FIGS. 1-1 and 1-2. 3-7 and 3-10 are bottom views. 3-8 and FIG. 3-11 are cross-sectional views of relevant parts corresponding to the direction AA in FIGS. 1-1 and 1-2. 3-9, FIG. 3-12, and FIG. 3-13 are principal part sectional views corresponding to the BB direction of FIG. 1-1 and FIG. 1-2. FIGS. 4A to 4E are process diagrams schematically showing a process of connecting the tab wire 21 to the back surface of the solar battery cell 1. FIGS.

First, for example, a p-type single crystal silicon substrate having a thickness of several hundred μm is prepared as the semiconductor substrate 2 (FIG. 3A). Since the p-type single crystal silicon substrate is manufactured by slicing an ingot formed by cooling and solidifying molten silicon with a wire saw, damage at the time of slicing remains on the surface. Therefore, the p-type single crystal silicon substrate is etched near the surface of the p-type single crystal silicon substrate by etching the surface by immersing the surface in an acid or heated alkaline solution, for example, an aqueous sodium hydroxide solution. Remove the damage area that exists in the. For example, the surface is removed by a thickness of 10 μm to 20 μm with an alkali solution such as sodium hydroxide or potassium hydroxide of several wt% to 20 wt%. Here, as a p-type silicon substrate used for the semiconductor substrate 2, a p-type single crystal silicon substrate having a specific resistance of 0.1Ω · cm to 5Ω · cm and having a (100) plane orientation will be described as an example.

Following damage removal, an additive that promotes anisotropic etching such as IPA (isopropyl alcohol) is added to the same alkaline low concentration solution, such as several wt% sodium hydroxide or potassium hydroxide. Anisotropic etching is performed with the solution. By this anisotropic etching, a micro-concave pattern 2a having a substantially quadrangular pyramid shape is formed on the light-receiving surface side and back surface side of the p-type single crystal silicon substrate so that the silicon (111) surface is exposed, thereby forming a texture structure. (Step S10, FIG. 3-2). That is, the texture structure is formed on the front and back surfaces of the p-type single crystal silicon substrate by wet etching (alkali texture method) using an alkaline solution.

Next, a pn junction is formed in the semiconductor substrate 2 (step S20, FIG. 3-3). That is, a group V element such as phosphorus (P) is diffused into the semiconductor substrate 2 to form the n-type impurity diffusion layer 3 having a thickness of several hundred nm. Here, a pn junction is formed by diffusing phosphorus oxychloride (POCl ₃ ) by thermal diffusion with respect to a p-type single crystal silicon substrate having a texture structure on the surface.

In this diffusion step, the p-type single crystal silicon substrate is placed in a mixed gas atmosphere of, for example, phosphorus oxychloride (POCl ₃ ) gas nitrogen gas and oxygen gas at a high temperature of, for example, 800 ° C. to 900 ° C. for several tens of minutes. Then, the n-type impurity diffusion layer 3 in which phosphorus (P) is diffused is uniformly formed in the surface layer of the p-type single crystal silicon substrate by thermal diffusion. Good electrical characteristics of the solar cell can be obtained when the sheet resistance range of the n-type impurity diffusion layer 3 formed on the surface of the semiconductor substrate 2 is about 30Ω / □ to 80Ω / □.

Here, the n-type impurity diffusion layer 3 is formed on the entire surface of the semiconductor substrate 2. For this reason, the front surface (light receiving surface) and the back surface of the semiconductor substrate 2 are in an electrically connected state. Therefore, in order to cut off this electrical connection, the end face region of the semiconductor substrate 2 is etched by dry etching, for example (FIG. 3-4). Further, a glassy (phosphosilicate glass, PSG: Phospho-Silicate Glass) layer deposited on the surface during the diffusion process is formed on the surface immediately after the formation of the n-type impurity diffusion layer 3. For this reason, the semiconductor substrate 2 is immersed in a hydrofluoric acid aqueous solution or the like to remove the PSG layer by etching.

Next, in order to improve the photoelectric conversion efficiency, an insulating film such as a silicon oxide film, a silicon nitride film, and a titanium oxide film is formed with a uniform thickness as an antireflection film 4 on one surface of the semiconductor substrate 11 on the light receiving surface side ( Step S30, FIG. 3-4). The film thickness and refractive index of the antireflection film 4 are set to values that most suppress light reflection. The antireflection film 4 is formed by using, for example, a plasma CVD method, using a mixed gas of silane (SiH ₄ ) gas and ammonia (NH ₃ ) gas as a raw material, and at 300 ° C. or higher and under reduced pressure. 4, a silicon nitride film is formed. The refractive index is, for example, about 2.0 to 2.2, and the optimum antireflection film thickness is, for example, 70 nm to 90 nm.

In addition, as the antireflection film 4, two or more films having different refractive indexes may be laminated. In addition to the plasma CVD method, the antireflection film 4 may be formed by vapor deposition, thermal CVD, or the like. It should be noted that the antireflection film 4 formed in this manner is an insulator, and simply forming the light receiving surface side electrode 12 on the surface does not act as a solar battery cell.

Next, the n-type impurity diffusion layer 3 formed on the back surface of the semiconductor substrate 2 is removed by diffusion of phosphorus (P). Thus, the semiconductor substrate 2 made of p-type single crystal silicon which is the first conductivity type layer, and the n-type impurity diffusion layer 3 which is the second conductivity type layer formed on the light receiving surface side of the semiconductor substrate 2, A semiconductor substrate 11 having a pn junction is obtained (FIGS. 3-5). In the case where the n-type impurity diffusion layer 3 is formed only on one surface of the semiconductor substrate 2, the above-described etching of the end surface region of the semiconductor substrate 2 and the removal of the n-type impurity diffusion layer 3 formed on the back surface of the semiconductor substrate 2 are performed. Is unnecessary.

Next, a back surface passivation film 7 made of a silicon nitride film (SiN film) is formed on the back surface side of the semiconductor substrate 11 (step S40, FIGS. 3-6). A back surface passivation film 7 made of a silicon nitride film (SiN film) having a refractive index of 1.9 to 2.2 and a thickness of 60 nm to 300 nm is formed on the silicon surface exposed on the back surface side of the semiconductor substrate 11 by, for example, plasma CVD. Form a film. By forming the back surface passivation film 7 as described above, the carrier recombination speed on the back surface of the semiconductor substrate 11 can be suppressed, and a sufficient back surface interface can be realized for high output.

Next, in the back surface passivation film 7, an opening 7a is formed in a region where a back aluminum paste for forming the back aluminum electrode 9 is applied (step S50, FIG. 3-7, FIG. 3-8, FIG. 3-9). The opening 7a is formed using, for example, a laser or an etching paste. If the back aluminum paste to be used can fire through the back surface passivation film 7, this step is not necessary. The opening 7a is formed in a comb-like pattern as shown in FIG. 3-7, for example. 3-8 is a cross-sectional view of the main part in the AA direction in FIG. 3-7. 3-9 is a cross-sectional view of the principal part in the BB direction in FIG. 3-7.

Next, electrodes are formed by screen printing. First, the light-receiving surface side electrode 12 is produced (before firing). That is, a silver paste, which is an electrode material paste containing glass frit, is applied to the shape of the front silver grid electrode 5 and the front silver bus electrode 6 on the antireflection film 4 that is the light receiving surface of the semiconductor substrate 11 by screen printing. Thereafter, the silver paste is dried (step S60).

Next, a back aluminum paste as an electrode material paste is applied to the shape of the back aluminum electrode 9 by screen printing on the back side of the semiconductor substrate 11 and dried (step S70). Here, the back aluminum paste is printed by filling the openings 7 a provided in the back surface passivation film 7.

Thereafter, the electrode paste on the front and back surfaces of the semiconductor substrate 11 is simultaneously fired at, for example, 600 ° C. to 900 ° C., so that the antireflection film 4 is melted with the glass material contained in the silver paste on the front side of the semiconductor substrate 11. During this time, the silver material comes into contact with the silicon and re-solidifies. Thereby, the surface silver grid electrode 5 and the surface silver bus electrode 6 as the light-receiving surface side electrode 12 are obtained, and conduction between the light-receiving surface side electrode 12 and the silicon of the semiconductor substrate 11 is ensured (step S80, FIG. 3). -10, Fig. 3-11, Fig. 3-12). Such a process is called a fire-through method. 3-11 is a cross-sectional view of the main part in the AA direction in FIG. 3-10. 3-12 is a cross-sectional view of the principal part in the BB direction in FIG. 3-10.

Also, the back aluminum paste reacts with the silicon of the semiconductor substrate 11 to obtain the back aluminum electrode 9, and the P + layer 10 is formed immediately below the back aluminum electrode 9. Further, the silver material of the silver paste comes into contact with silicon and re-solidifies to obtain the back silver electrode 8. In the figure, only the front silver grid electrode 5 and the back aluminum electrode 9 are shown.

Next, a back silver sputtering film 8 is formed as a high light reflection film on the back surface passivation film 7 on the back surface of the semiconductor substrate 11 by sputtering (step S90, FIG. 3-13). Note that there is no particular problem even if silver is sputtered on the back aluminum electrode 9.

By performing the above steps, the solar battery cell 1 according to the present embodiment shown in FIGS. 1-1 to 1-4 is obtained. In addition, the order of arrangement of the paste, which is an electrode material, on the semiconductor substrate 11 may be switched between the light receiving surface side and the back surface side.

Next, a method of connecting the tab wire 21 to the back surface of the solar battery cell 1 formed in this way will be described. FIG. 4A is a bottom view of the solar battery cell 1 viewed from the side opposite to the light receiving surface (back surface).

First, the conductive film 22 is stuck on the line where the square portions of the back aluminum electrode 9 on the back surface of the solar battery cell 1 are arranged (step S100, FIG. 4-2). The conductive film 22 is a film-like anisotropic conductive adhesive, and is composed of an adhesive (binder) for fixing between conductive members and conductive particles uniformly dispersed in the binder. Both surfaces of the conductive film 22 have adhesiveness, and the other surface side of the conductive film 22 in a state where the tabbed separator 23 is attached to the one surface side is used as the back aluminum on the back surface of the solar battery cell 1. It sticks on the line in which the square part of the electrode 9 was located in a line.

Next, the tab-attached separator 23 attached to one side of the conductive film 22 is peeled off (step S110, FIG. 4-3, FIG. 4-4).

Next, the tab wire 21 is bonded to the one surface side of the conductive film 22 exposed by peeling off the tab attaching side separator 23 (step S120), and a temperature of 200 ° C. or lower and a predetermined pressing force are applied to the tab wire 21, for example. . Thus, one end side of the tab wire 21 is electrically and mechanically connected to the back aluminum electrode 9 on the back surface of the solar battery cell 1 through the conductive film 22 (step S130, FIG. 4-5). Note that the other end side of the tab wire 21 is electrically connected to another solar battery cell or the like.

As described above, in the first embodiment, the back silver sputtering film 8 which is a high light reflection film having a higher light reflectivity than the aluminum electrode formed of aluminum paste is provided as the light reflection film on the back surface. Thereby, compared with the conventional photovoltaic cell provided with the aluminum electrode formed with the aluminum paste on the entire back surface, the light reflectance on the back surface can be improved, and the solar cell 1 is transmitted and reaches the back surface. The light thus used can be effectively utilized, and the photoelectric conversion efficiency can be improved by light reflection on the back surface.

In the first embodiment, the tab wire 21 is electrically and mechanically connected to the back aluminum electrode 9 on the back surface of the solar battery cell 1 using the conductive film 22. Therefore, the back silver electrode on the back surface, the soldered tab wire and the flux, which are necessary for the tab line connection on the back surface side of the silicon substrate in the normal module process, are not required, and the connection of the tab wire 21 to the solar cell 1 is easy. become. And since silver is an expensive material, the photovoltaic cell 1 can be implement | achieved cheaply by the back silver electrode of a back surface becoming unnecessary.

Therefore, according to the first embodiment, the photoelectric conversion efficiency is improved by light reflection on the back surface, and the solar battery cell 1 in which the tab wire 21 can be easily connected to the back aluminum electrode 9 can be obtained at low cost. This makes it possible to easily tab the solar cell 1 with high photoelectric conversion efficiency.

Embodiment 2. FIG.
Embodiment 2 demonstrates the other high light reflective film of the back surface of a photovoltaic cell. According to International Publication No. 2010/150358, a technique using an aluminum foil as a conventional high light reflection film is proposed. On the other hand, International Publication No. 2010/150358 does not specifically mention the tab line connection method. In the second embodiment, a method for connecting tab wires when an aluminum foil is used as the high light reflection film will be described.

FIG. 5A is a top view schematically showing the aluminum foil 31 with a conductive film according to the second embodiment. FIG. 5-2 is a cross-sectional view schematically showing the aluminum foil 31 with a conductive film according to the second embodiment, and is a main-portion cross-sectional view in the CC direction of FIG. 5-1. The aluminum foil 31 with a conductive film according to the second embodiment is configured by holding the conductive film 22 on one side of an aluminum foil 32 having a surface shape equivalent to that of the semiconductor substrate 11.

On the aluminum foil 32, there are two regions corresponding to the connection region of the tab wire 21 on the back surface of the solar battery cell 1, that is, the attachment region of the conductive film 22. It has an opening 32a that is generally smaller than the sticking area) and has an equivalent shape. The two conductive films 22 are held on one side of the aluminum foil 32 so that the other side covers the opening 32a with the tab-attached separator 23 attached to the one side. Yes. The conductive film 22 is temporarily bonded to the outer peripheral region of the opening 32a in the aluminum foil 32 by the adhesive force on the other surface side.

Next, a method for connecting the tab wires 21 using the aluminum foil 31 with a conductive film will be described. 6A and 6B are process diagrams schematically showing a process of connecting a tab to the back surface of the solar battery cell when using the aluminum foil 31 with the conductive film according to the second embodiment. FIG. 6A is a bottom view showing the state of the semiconductor substrate 11 at the end of the baking process of step S80 in the first embodiment, and shows the same state as FIG. 3-10. After the firing step, in the state shown in FIG. 6A, the aluminum foil 31 with a conductive film is attached to the back surface of the semiconductor substrate 11 with the surface on which the tab-attached separator 23 is attached facing outward (FIG. 6- 2).

At this time, the position of the opening 32a (the position of the conductive film 22) is aligned and adhered to the line where the square portions of the back aluminum electrode 9 are arranged on the back surface of the semiconductor substrate 11. The aluminum foil 31 with a conductive film is temporarily bonded to the back surface of the semiconductor substrate 11 by the adhesive force of the other surface of the conductive film 22 exposed from the opening 32a.

Next, the tab attaching side separator 23 is peeled off, and the tab wire 21 is adhered to one side of the conductive film 22 exposed by peeling off the tab attaching side separator 23, and heating and heating are performed in the same manner as in the first embodiment. Apply pressure. Thereby, the tab wire 21 is electrically and mechanically connected to the back aluminum electrode 9 on the back surface of the solar battery cell 1 through the conductive film 22.

Then, when the solar battery cell 1 is laminated using a sealing material in the subsequent module process, the aluminum foil 32 part is brought into close contact with and adhered to the back surface passivation film 7 on the back surface of the solar battery cell 1.

As described above, in the second embodiment, the aluminum foil 32 which is a high light reflection film having a higher light reflectivity than the aluminum electrode formed of aluminum paste is provided as the light reflection film on the back surface. Thereby, compared with the conventional photovoltaic cell provided with the aluminum electrode formed with the aluminum paste on the entire back surface, the light reflectance on the back surface can be improved, and the solar cell 1 is transmitted and reaches the back surface. The light thus used can be effectively utilized, and the photoelectric conversion efficiency can be improved by light reflection on the back surface.

In the second embodiment, similarly to the first embodiment, the tab wire 21 is electrically and mechanically connected to the back aluminum electrode 9 on the back surface of the solar battery cell 1 using the conductive film 22. . Therefore, the back silver electrode on the back surface, the soldered tab wire and the flux, which are necessary for the tab line connection on the back surface side of the silicon substrate in the normal module process, are not required, and the connection of the tab wire 21 to the solar cell 1 is easy. become. And since silver is an expensive material, the photovoltaic cell 1 can be implement | achieved cheaply by the back silver electrode of a back surface becoming unnecessary.

And in Embodiment 2, the simplification of a manufacturing process is realizable by using the aluminum foil 31 with an electroconductive film in which the electroconductive film 22 and the aluminum foil 32 which is a high light reflection film were integrated.

Therefore, according to the second embodiment, similar to the first embodiment, the photoelectric conversion efficiency is improved by the light reflection on the back surface, and the solar battery cell in which the tab wire 21 can be easily connected to the back aluminum electrode 9. 1 is obtained at low cost. This makes it possible to easily tab the solar cell 1 with high photoelectric conversion efficiency.

Embodiment 3 FIG.
Embodiment 3 demonstrates the other high light reflective film of the back surface of a photovoltaic cell. In Embodiment 3, an example will be described in which a high light reflection film having a higher light reflectivity than an aluminum electrode formed of an aluminum paste is formed using a liquid material. 7A to 7D are bottom views of the semiconductor substrate 11 schematically showing the method for forming the high light reflection film according to the third embodiment. FIG. 7-1 is a bottom view showing the state of the semiconductor substrate 11 at the end of the baking step of step S80 in the first embodiment, and shows the same state as FIG. 3-10.

In the state of FIG. 7A, the conductive film 22 is stuck on the line where the square portions of the back aluminum electrode 9 on the back surface of the solar battery cell 1 are arranged. Here, in Embodiment 3, the other surface side of the conductive film 22 in a state where the liquid repellent tab-attached separator 41 having liquid repellency such as hydrophobicity is attached to the one surface side. It adheres on the line where the square portions of the back aluminum electrode 9 on the back surface of the solar battery cell 1 are arranged (FIG. 7-2).

Next, the high light reflection film intermediate material 42, which is a chemical solution that functions as a high light reflection film by solidifying with heat or light without peeling off the liquid repellent tab-attached separator 41, is applied using a coating method such as spin coating. It is applied to the back surface of the solar battery cell 1 (FIG. 7-3). At this time, the surface of the liquid repellent tabbed side separator 41 is provided with a liquid repellent property that repels the high light reflective film intermediate material 42, so that the surface of the liquid repellent tabbed side separator 41 has a high light reflective film. The intermediate material 42 is not applied. Thereby, the high light reflection film intermediate material 42 can be selectively applied to a region other than the connection portion of the tab wire 21 on the back surface of the solar battery cell 1.

Next, after drying the high light reflective film intermediate material 42, the liquid repellent tabbed side separator 41 is peeled off, and the liquid repellent tabbed side separator 41 is peeled off and exposed on the other surface side of the conductive film 22. The tab wire 21 is bonded, and heating and pressing are performed in the same manner as in the first embodiment. Thereby, the tab wire 21 is electrically and mechanically connected to the back aluminum electrode 9 on the back surface of the solar battery cell 1 through the conductive film 22 (FIG. 7-4).

When the high light reflection film intermediate material 42 that functions as a high light reflection film by solidifying with heat is used, the high light reflection film intermediate material 42 is solidified by heating at the time of tab connection, and the high light reflection film 43 is formed. . If the high light reflection film intermediate material 42 is not completely solidified by heating at the time of tab connection, additional heating may be performed after the connection of the tab wire 21 to solidify the high light reflection film intermediate material 42. Further, in the case of using the high light reflection film intermediate material 42 which is a chemical liquid that is solidified by light and functions as a high light reflection film, for example, the high light reflection film intermediate material 42 is solidified by irradiating ultraviolet rays. Is formed. The timing of ultraviolet irradiation may be before the tab wire 21 is bonded and after the tab wire 21 is bonded.

As described above, in the third embodiment, as in the first embodiment, the high light reflection film which is a high light reflection film having a higher light reflectance than the aluminum electrode formed of aluminum paste as the light reflection film on the back surface. 43 is provided. Thereby, compared with the conventional photovoltaic cell provided with the aluminum electrode formed with the aluminum paste on the entire back surface, the light reflectance on the back surface can be improved, and the solar cell 1 is transmitted and reaches the back surface. The light thus used can be effectively utilized, and the photoelectric conversion efficiency can be improved by light reflection on the back surface.

In the third embodiment, similarly to the first embodiment, the tab wire 21 is electrically and mechanically connected to the back aluminum electrode 9 on the back surface of the solar battery cell 1 using the conductive film 22. . Therefore, the back silver electrode on the back surface, the soldered tab wire and the flux, which are necessary for the tab line connection on the back surface side of the silicon substrate in the normal module process, are not required, and the connection of the tab wire 21 to the solar cell 1 is easy. become. And since silver is an expensive material, the photovoltaic cell 1 can be implement | achieved cheaply by the back silver electrode of a back surface becoming unnecessary.

And in Embodiment 3, the back surface aluminum electrode of the back surface of the photovoltaic cell 1 is made into the electroconductive film 22 in the state by which the liquid-repellent tab attachment side separator 41 which has liquid repellency is stuck on the one surface side. 9 is stuck on the line in which the square portions are arranged, and the liquid high light reflection film intermediate material 42 is applied to the back surface of the solar battery cell 1. Thereby, a high light reflection film can be easily formed selectively with respect to a region other than the connection portion of the tab wire 21 on the back surface of the solar battery cell 1.

Therefore, according to the third embodiment, similar to the first embodiment, the photoelectric conversion efficiency is improved by light reflection on the back surface, and the solar battery cell in which the tab wire 21 can be easily connected to the back aluminum electrode 9. 1 is obtained at low cost. This makes it possible to easily tab the solar cell 1 with high photoelectric conversion efficiency.

Embodiment 4 FIG.
In embodiment mentioned above, in order to suppress the recombination rate of the carrier in the back surface of the photovoltaic cell 1, the structure which uses the back surface passivation film 7 was demonstrated. The back surface passivation film 7 is often an insulating film and cannot be electrically connected even if physically connected to the conductive film 22, and does not contribute to current collection on the back surface of the solar battery cell 1. In Embodiment 4, in order to suppress the recombination rate of the back surface of the solar battery cell, a case will be described in which the back surface BSF layer is formed by diffusion of impurities with respect to the back surface of the solar battery cell instead of the back surface passivation film.

FIGS. 8A and 8B are cross-sectional views schematically showing the method for manufacturing the solar battery cell according to the fourth embodiment. FIG. 8-1 is a bottom view showing the state of the semiconductor substrate 11 at the end of removal of the n-type impurity diffusion layer 3 formed on the back surface of the semiconductor substrate 2 in the first embodiment, and is the same as FIG. 3-5 It is a figure which shows a state. In the state of FIG. 8A, boron, which is a p-type impurity, is diffused over the entire surface of the back surface of the semiconductor substrate 11, and the boron diffusion layer 51 is p-type and has a higher impurity concentration than the semiconductor substrate 2. Is formed (FIG. 8-2). The boron diffusion layer 51 becomes a P + layer to form a BSF layer, and reduces the recombination rate of carriers on the back surface of the solar battery cell.

Thereafter, in the same manner as in the first to third embodiments, a high light reflective film on the back surface is formed as the electrode layer, the light receiving surface side electrode 12 is formed, and the conductive film 22 is adhered. Here, in Embodiment 4, since the P + layer is present on the entire back surface of the solar battery cell and the resistance on the back surface side of the solar battery cell is low, the semiconductor substrate 11 is not formed without forming the back aluminum electrode. The conductive film 22 is directly attached to the boron diffusion layer 51 on the back surface of the substrate.

Thereby, a boron diffusion layer 51 for reducing the carrier recombination speed on the back surface of the solar battery cell is provided instead of the back surface passivation film, and a solar battery cell with the conductive film 22 having a high light reflection structure on the back surface is easily manufactured. can do. Then, the tab wire 21 can be easily connected to the solar battery cell 1 by connecting the tab wire 21 in the same manner as in the first to third embodiments. Further, the boron diffusion layer 51 on the back surface of the semiconductor substrate 11 and the conductive film 22 can be directly and physically connected.

By the way, in this case, although the P + layer exists on the entire back surface of the solar battery cell and the resistance on the back surface side of the solar battery cell is low, the current cannot be collected efficiently with only the two tab wires 21. Is also possible. However, the resistance on the back surface side is clearly lower than that of the conventional solar cell provided with the aluminum electrode for collecting current and the silver electrode for tab connection on the back surface. For this reason, even if the shape of the comb-shaped electrode pattern is adopted as the shape of the back surface side electrode as a countermeasure against the decrease in current collection, the number and width of the back surface side electrode can be greatly reduced. Thereby, it leads to the consumption cost reduction of aluminum and silver for electrodes, and an inexpensive solar cell can be realized.

As described above, in the fourth embodiment, as in the first embodiment, a high light reflection film having a higher light reflectance than the aluminum electrode formed of aluminum paste is provided as the light reflection film on the back surface. . Thereby, compared with the conventional solar cell provided with an aluminum electrode formed of an aluminum paste on the entire back surface, the light reflectance on the back surface can be improved, and the solar cell is transmitted and reaches the back surface. Light can be used effectively, and the photoelectric conversion efficiency can be improved by light reflection on the back surface.

In the fourth embodiment, the tab wire 21 is electrically and mechanically connected to the boron diffusion layer 51 on the back surface of the semiconductor substrate 11 using the conductive film 22. Therefore, the back silver electrode on the back surface, the soldered tab wire and the flux, which are necessary for the tab line connection on the back surface side of the silicon substrate in the normal module process, are not required, and the connection of the tab wire 21 to the solar cell 1 is easy. become. Since silver is an expensive material, a solar battery cell can be realized at low cost by eliminating the need for a back silver electrode on the back surface.

And in Embodiment 4, the boron diffusion layer 51 which reduces the recombination rate of the carrier in the back surface of the photovoltaic cell 1 is provided instead of a back surface passivation film. Thereby, the back surface of the semiconductor substrate 11 can be physically and electrically directly connected to the conductive film 22, and good current collection can be realized.

Therefore, according to the fourth embodiment, as in the first embodiment, the photovoltaic conversion efficiency is improved by light reflection on the back surface, and the solar cell in which the tab wire 21 is easily connected to the back surface of the solar battery cell. A cell can be obtained at low cost. Thereby, it is possible to easily tab the solar cell having high photoelectric conversion efficiency.

As described above, the solar cell according to the present invention is useful for realizing a solar cell in which the tab line can be easily connected to the back surface and the photoelectric conversion efficiency is improved by the light reflection on the back surface. .

1 solar cell, 2 semiconductor substrate, 2a minute unevenness, 3 n-type impurity diffusion layer, 4 antireflection film, 5 surface silver grid electrode, 6 surface silver bus electrode, 7a opening, 7 back surface passivation film, 8 back silver sputtering Membrane, 9 back aluminum electrode, 10 P + layer, 11 semiconductor substrate, 12 light receiving surface side electrode, 13 back surface side electrode, 21 tab wire, 22 conductive film, 23 tabbed side separator, 31 aluminum foil with conductive film, 32 Aluminum foil, 32a opening, 41 liquid-repellent tabbed separator, 42 high light reflective film intermediate material, 43 high light reflective film, 51 boron diffusion layer.

Claims (11)

A first conductivity type semiconductor substrate having an impurity diffusion layer in which an impurity element of the second conductivity type is diffused on one side;
A light-receiving surface side electrode electrically connected to the impurity diffusion layer and formed on one surface side of the semiconductor substrate;
Light reflectivity higher than that of an aluminum electrode formed of aluminum paste, and is formed in a partial region on the other surface side of the semiconductor substrate, and reflects light transmitted through the semiconductor substrate from one surface side of the semiconductor substrate. A light reflecting layer
A connection layer for connecting a tab wire for electrically connecting the other surface side of the semiconductor substrate and another solar battery cell, on a region excluding the light reflection layer on the other surface side of the semiconductor substrate. An attached conductive film;
A solar battery cell comprising: A back side electrode mainly composed of aluminum formed in a region different from the formation region of the light reflection layer on the other surface side of the semiconductor substrate;
A first BSF layer formed under the backside electrode in the surface layer on the other surface side of the semiconductor substrate and having a first conductivity type impurity diffused at a higher concentration than the semiconductor substrate;
With
That the conductive film is adhered on the back side electrode;
The solar battery cell according to claim 1. Comprising a passivation film between the surface of the other side of the semiconductor substrate and the light reflecting layer;
The solar battery cell according to claim 2. A second BSF layer in which impurities of the first conductivity type are diffused at a higher concentration than the semiconductor substrate is formed on the entire surface layer on the other surface side of the semiconductor substrate;
The conductive film is directly attached to the second BSF layer;
The solar battery cell according to claim 1. The light reflecting layer is an aluminum foil;
The solar battery cell according to any one of claims 1 to 4, wherein: A first step of forming a second conductivity type impurity diffusion layer on one surface side of the first conductivity type semiconductor substrate;
A light reflection layer that has a higher light reflectivity than an aluminum electrode formed of aluminum paste and reflects light transmitted through the semiconductor substrate from one surface side of the semiconductor substrate is formed in a partial region on the other surface side of the semiconductor substrate. A second step of forming;
A third step of forming an electrode electrically connected to the impurity diffusion layer on one side of the semiconductor substrate;
The conductive film which is a connection layer for connecting a tab wire for electrically connecting the other surface side of the semiconductor substrate and other solar cells is removed from the light reflecting layer on the other surface side of the semiconductor substrate. A fourth step of sticking on the area;
The manufacturing method of the photovoltaic cell characterized by including. Forming a back-side electrode mainly composed of aluminum in a region different from the formation region of the light reflecting layer on the other surface side of the semiconductor substrate;
Forming a first BSF layer in which impurities of a first conductivity type are diffused at a higher concentration than the semiconductor substrate below the back surface side electrode in the surface layer on the other surface side of the semiconductor substrate;
Have
In the fourth step, the conductive film is stuck on the back surface side electrode,
The manufacturing method of the photovoltaic cell of Claim 6 characterized by these. Forming a passivation film between the surface of the other side of the semiconductor substrate and the light reflecting layer in the second step;
The manufacturing method of the photovoltaic cell of Claim 7 characterized by these. Forming a second BSF layer in which impurities of the first conductivity type are diffused at a higher concentration than the semiconductor substrate on the entire surface layer on the other surface side of the semiconductor substrate;
In the fourth step, directly attaching the conductive film to the second BSF layer;
The manufacturing method of the photovoltaic cell of Claim 6 characterized by these. Covering the opening provided in the aluminum foil, the conductive film is attached to one side of the aluminum foil, and the conductive film is attached to the other side of the semiconductor substrate. Forming the light reflecting layer by adhering to the surface layer on the side,
The method for producing a solar battery cell according to any one of claims 6 to 9, wherein: On the surface opposite to the surface attached to the other surface side of the semiconductor substrate in the conductive film, a liquid repellent tabbed side separator having liquid repellency is provided,
After the conductive film is attached to the other surface side of the semiconductor substrate, the light intermediate layer is applied to the other surface side of the semiconductor substrate to solidify the light. Forming a reflective layer;
The method for producing a solar battery cell according to any one of claims 6 to 9, wherein:

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