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WO2018109878A1 - Batterie solaire et procédé de fabrication de batterie solaire - Google Patents

Batterie solaire et procédé de fabrication de batterie solaire Download PDF

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Publication number
WO2018109878A1
WO2018109878A1 PCT/JP2016/087274 JP2016087274W WO2018109878A1 WO 2018109878 A1 WO2018109878 A1 WO 2018109878A1 JP 2016087274 W JP2016087274 W JP 2016087274W WO 2018109878 A1 WO2018109878 A1 WO 2018109878A1
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Prior art keywords
film
solar cell
silicon substrate
diffusion layer
diffusion
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English (en)
Japanese (ja)
Inventor
陽一郎 西本
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Mitsubishi Electric Corp
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Mitsubishi Electric Corp
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Priority to PCT/JP2016/087274 priority Critical patent/WO2018109878A1/fr
Priority to JP2018556100A priority patent/JP6647425B2/ja
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Anticipated expiration legal-status Critical
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    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10F—INORGANIC SEMICONDUCTOR DEVICES SENSITIVE TO INFRARED RADIATION, LIGHT, ELECTROMAGNETIC RADIATION OF SHORTER WAVELENGTH OR CORPUSCULAR RADIATION
    • H10F10/00—Individual photovoltaic cells, e.g. solar cells
    • H10F10/10—Individual photovoltaic cells, e.g. solar cells having potential barriers
    • H10F10/14—Photovoltaic cells having only PN homojunction potential barriers
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10F—INORGANIC SEMICONDUCTOR DEVICES SENSITIVE TO INFRARED RADIATION, LIGHT, ELECTROMAGNETIC RADIATION OF SHORTER WAVELENGTH OR CORPUSCULAR RADIATION
    • H10F71/00—Manufacture or treatment of devices covered by this subclass
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10F—INORGANIC SEMICONDUCTOR DEVICES SENSITIVE TO INFRARED RADIATION, LIGHT, ELECTROMAGNETIC RADIATION OF SHORTER WAVELENGTH OR CORPUSCULAR RADIATION
    • H10F77/00—Constructional details of devices covered by this subclass
    • H10F77/30—Coatings
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E10/00—Energy generation through renewable energy sources
    • Y02E10/50—Photovoltaic [PV] energy
    • Y02E10/547—Monocrystalline silicon PV cells
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P70/00—Climate change mitigation technologies in the production process for final industrial or consumer products
    • Y02P70/50—Manufacturing or production processes characterised by the final manufactured product

Definitions

  • the present invention relates to a solar cell using crystalline silicon and a method for manufacturing the solar cell.
  • One structure of a solar cell has a conductivity opposite to the conductivity type of the crystalline silicon substrate on the light receiving surface, which is the surface on which the sunlight of a crystalline silicon (Si) substrate including single crystal or polycrystal is incident.
  • a pn junction is formed on the light receiving surface side by diffusing impurities to be a mold.
  • a high-concentration diffusion layer having the same conductivity type as that of the substrate is provided on the back surface, and recombination of minority carriers is suppressed by the back surface field effect to achieve high output.
  • This high-concentration diffusion layer on the back surface is called a BSF (Back Surface Field) layer.
  • the BSF layer is formed by combining a baking process of aluminum (Al) paste with the formation of the back electrode and forming a high-concentration diffusion layer by diffusion of aluminum during baking. Formation is realized.
  • the crystalline silicon substrate may be referred to as a silicon substrate or a substrate, and the solar battery cell as a cell.
  • the silicon substrate occupies most of the material cost, thinning the substrate is effective in reducing the cost.
  • the formation of the BSF layer at the time of forming the back electrode by firing the aluminum paste causes a large warp in the substrate after firing, and the substrate can be thinned with the current cell structure. Is difficult.
  • a PERC (Passive Emitter and Rear Cell) cell which has been known as a high conversion efficiency cell, has not warped even if the substrate is thin.
  • the passivation film is disposed on the back surface of the substrate, the back electrode is connected to the substrate through a contact hole, and the substrate is made of Al (Al) formed by contact with silicon. This is because the area of the Si alloy portion is reduced.
  • the high conversion efficiency of the PERC cell is due to the passivation film disposed on the back surface, but a passivation film suitable for the p-type surface has not been found for a while.
  • an aluminum oxide (Al 2 O 3 ) film is suitable as a passivation film on the back surface, and PERC cells using the Al 2 O 3 film are being mass-produced.
  • TMA Trimethyl Aluminum
  • Al 2 O 3 film which is a raw material for forming the Al 2 O 3 film
  • TMA has a problem that it is a substance that is difficult to use in the production of solar cells.
  • a solar cell that achieves a thin substrate has a BSF layer (B-BSF) made of a boron diffusion layer by diffusing boron (B) on the back surface as shown in Patent Document 1.
  • B-BSF BSF layer
  • Formed solar cells have also been proposed. This is because, since boron does not form an alloy with silicon, it is considered that a solar cell with B-BSF formed is less likely to warp the substrate than an Al-BSF cell with an Al-Si alloy formed on the back surface.
  • solar cells formed with B-BSF have not been put into practical use. The reason why the solar battery cell formed with B-BSF is not put into practical use is the diffusion method of boron and the passivation film on the back surface.
  • Patent Document 1 boron is diffused by vapor phase diffusion.
  • BSG Boron Silicate Glass
  • the substrate surface is clean. There is no hydrophobic surface as a proof of the surface.
  • the reason why the substrate surface after the removal of the BSG film does not become a hydrophobic surface is that a boron silicide layer is formed on the substrate surface. If there is a boron silicide layer on the substrate surface, recombination of hole electron pairs is likely to occur, and a cell having high conversion characteristics cannot be produced.
  • the boron silicide layer generated at the interface between the BSG film and the substrate is a silicon layer with a high boron content and is also called a boron rich layer. Therefore, it is necessary to remove this boron silicide layer, and generally, a process of thermally oxidizing the substrate and removing the oxide film again is performed. However, it is also known that impurities gettered in the boron silicide layer are re-emitted during thermal oxidation, which degrades the crystal quality of the substrate.
  • Patent Document 2 discloses a technique of forming a laminated film of a BSG film and an NSG (Non Doped Silicate Glass) film on a substrate surface and forming a p-type diffusion layer by heat treatment. Is presented.
  • An object of the present invention is to obtain a solar cell that can be thinned, is easy to manufacture, and has high conversion efficiency.
  • a solar cell of the present invention includes a silicon substrate, a diffusion layer provided on the first surface of the silicon substrate, and containing a first conductivity type element, A first glass layer including a first conductivity type element and silicon (hereinafter also referred to as silicon); and a first conductivity type element stacked on the first glass layer. And a passivation film having a second glass layer containing silicon.
  • the present invention it is possible to obtain a solar cell that can be thinned, can be easily manufactured, and has high conversion efficiency.
  • FIG. 1 It is sectional drawing which shows the solar cell of Embodiment 1 typically, and is II sectional drawing of FIG. Top view of solar cell of Embodiment 1
  • Process sectional drawing which shows the manufacturing process of the solar cell of Embodiment 1 Flowchart showing the manufacturing process of the solar cell of the first embodiment.
  • Comparison diagram of open-circuit voltage Voc and short-circuit photocurrent density Jsc of the solar battery of the first embodiment and the solar battery of the comparative example The figure which shows the relationship between the internal quantum efficiency of the solar cell of Embodiment 1, and a wavelength.
  • FIG. 1 is a cross-sectional view schematically showing the solar cell of Embodiment 1, and FIG. 2 is a top view thereof.
  • FIG. 1 is a sectional view taken along line II of FIG.
  • the solar cell 10 of Embodiment 1 includes a BSG film 12 used as a diffusion source for forming a p + -type diffusion layer 14 which is a BSF layer on the back surface 11B side of the p-type single crystal silicon substrate 11 and a cap layer.
  • the used laminated film with the NSG film 13 is left as it is to form a passivation film Pa.
  • the solar cell 10 has a concavo-convex structure having a texture that reduces light reflection on a light receiving surface 11A that is a first main surface of a p-type single crystal silicon substrate 11 that is a first conductivity type semiconductor substrate. Is formed. No texture is formed on the back surface 11B which is the second main surface facing the light receiving surface 11A of the p-type single crystal silicon substrate 11, and a p + -type diffusion layer 14 which is a first conductivity type semiconductor layer is provided. . Then, the BSG film 12 which is the first glass layer used as the diffusion source for forming the p + -type diffusion layer 14 and the NSG film 13 which is the second glass layer used for the cap layer are left, and the passivation is performed.
  • a film Pa is formed.
  • an n-type diffusion layer 15 that is a second conductivity type semiconductor layer is formed on a textured uneven structure, and an antireflection film 16 is formed on the n-type diffusion layer 15 by being laminated.
  • a light receiving surface grid electrode 17G and a light receiving surface bus electrode 17B which are first current collecting electrodes on the light receiving surface 11A side, are formed on the antireflection film 16, and the light receiving surface grid electrode 17G and the light receiving surface bus electrode 17B are formed. Is in contact with the n-type diffusion layer 15 through the antireflection film 16.
  • the back surface grid electrode is formed so as to be orthogonal to the back surface bus electrode, and the back surface electrode 18 is configured to penetrate the passivation film Pa.
  • the present inventor has obtained a laminated film of the BSG film 12 formed as a diffusion source and the NSG film 13 formed on the cap layer. It has been found that it is suitable for the passivation film Pa of the p-type diffusion layer by boron diffusion.
  • a laminated film of the BSG film 12 and the NSG film 13 is used as the passivation film Pa. For this reason, since it is not necessary to form the passivation film Pa newly, a solar cell with high conversion efficiency can be manufactured, simplifying a manufacturing process.
  • the Al—Si alloy layer is not formed as in the case of the Al—BSF cell, the occurrence of warpage of the substrate due to the formation of the Al—Si alloy layer can be suppressed, and a thin silicon substrate can be used. Moreover, since the price of material gases such as diborane (B 2 H 6 ) and silane (SiH 4 ) as film forming materials is lower than that of TMA, it can contribute to reduction of power generation cost.
  • material gases such as diborane (B 2 H 6 ) and silane (SiH 4 ) as film forming materials is lower than that of TMA, it can contribute to reduction of power generation cost.
  • the concentration of boron which is the first conductivity type element, continuously changes at the interface between the BSG film 12 and the p + -type diffusion layer 14. For this reason, recombination of electrons and holes hardly occurs, and good interface characteristics can be obtained.
  • the atomic density of the interface and the periphery of the interface can be measured by various measuring apparatuses such as secondary ion mass spectrometry (SIMS).
  • FIG. 3 is a process cross-sectional view illustrating the manufacturing process of the solar cell of the first embodiment.
  • FIG. 4 is a flowchart showing manufacturing steps of the solar cell of the first embodiment.
  • a p-type single crystal silicon substrate 11 is prepared. Regardless of whether it is polycrystalline silicon or single crystal silicon, the substrate for the solar cell is delivered in an as-sliced state, so that damage during slicing remains on the substrate surface. Therefore, first, in the damaged layer removing step S101 shown in FIG. 4, the damaged layer on the surface of the p-type single crystal silicon substrate 11 is removed by etching.
  • etching an alkaline chemical solution is often used from the viewpoint of cost, but there is no problem even if a hydrofluoric acid mixed acid is used.
  • this operation is merely an operation for removing the damaged layer, and it is not necessary to form a minute uneven structure for reducing the reflectance called texture. If the texture is formed at this time, the texture is also formed on the back surface 11B of the p-type single crystal silicon substrate 11, and the characteristics of the solar cell 10 may be deteriorated instead. This point will be described later.
  • a BSG film 12 serving as a diffusion source and an NSG film serving as a cap layer on the back surface 11B side of the p-type single crystal silicon substrate 11 13 are laminated.
  • the p-type single crystal silicon substrate 11 is annealed to diffuse boron in the BSG film 12 into the p-type single crystal silicon substrate 11, and the back surface 11B side A p + -type diffusion layer 14 is formed on the surface layer.
  • the NSG film 13 is not present, boron is also released into the annealing atmosphere, so that the boron concentration in the BSG film 12 is lowered and boron is not effectively diffused into the p-type single crystal silicon substrate 11. Therefore, in order to prevent boron from being released into the annealing atmosphere, an NSG film 13 is formed on the BSG film 12 as a cap layer.
  • the boron concentration in the BSG film 12 is 1.18 wt%
  • the film thicknesses of the BSG film 12 and the NSG film 13 are 70 nm and 300 nm, respectively, and annealing is performed in a nitrogen (N 2 ) atmosphere at 1000 ° C.-60 min. went.
  • the substrate temperature may be 900 ° C. to 1100 ° C. If the substrate temperature is less than 900 ° C., sufficient diffusion cannot be achieved. On the other hand, there is no problem even if the substrate temperature exceeds 1100 ° C. However, since sufficient diffusion is possible at 1000 ° C., the merit of further increasing the temperature is small considering the cost.
  • annealing was performed in an N 2 atmosphere, but a small amount of phosphorus oxychloride (POCl 3 ) and oxygen (O 2 ) may be flowed during annealing or cooling.
  • the contamination source may be diffused from the surface of the p-type single crystal silicon substrate 11 into the p-type single crystal silicon substrate 11 to deteriorate the crystal quality.
  • POCl 3 and O 2 By flowing POCl 3 and O 2 during annealing or cooling, a phosphorus diffusion layer is formed on the surface of the p-type single crystal silicon substrate 11, and the gettering effect by this phosphorus diffusion layer reduces the influence of contamination from the apparatus. Can be expected to do.
  • this phosphorus diffusion layer is removed by etching in the next texture forming step, it does not affect the subsequent steps. Since phosphorus is more easily diffused than boron, this phosphorus diffusion layer is likely to be thick, but if the phosphorus diffusion layer becomes too thick, it will be difficult to remove in the texture forming process, so that the phosphorus diffusion layer will not be too thick. It is necessary to keep in mind.
  • This diffusion method is solid phase diffusion using the BSG film 12 as a diffusion source.
  • Boron such as boron bromide (BBr 3 ) and boron chloride (BCl 3 ) in addition to solid phase diffusion is used for boron diffusion.
  • a cell using boron diffusion by vapor phase diffusion for example, a cell in which boron diffusion is performed by vapor phase diffusion on an n-type single crystal silicon substrate and a pn junction is formed uses a film formed by a CVD method. The conversion efficiency and other characteristics are lower than those of a cell in which a pn junction is formed by the diffusion method described above. This is due to the difference in the surface state of the n-type single crystal silicon substrate after diffusion.
  • a boron silicide layer which is a boron-rich layer, is formed even if the BSG film formed during diffusion is removed, and carriers are recombined in this boron silicide layer. End up. Therefore, it is necessary to remove this boron silicide layer, and generally, a process of thermally oxidizing the substrate and removing the oxide film again is performed. However, during thermal oxidation, impurities gettered to the boron silicide layer are re-emitted and the crystal quality is degraded. For this reason, it is difficult to obtain high cell characteristics by boron vapor phase diffusion.
  • the boron concentration in the BSG film can be controlled at the time of film formation. Therefore, the formation of a boron silicide layer can be suppressed by selecting an appropriate concentration. it can.
  • the presence or absence of the boron silicide layer can be determined by removing the BSG film with hydrofluoric acid (HF) after diffusion. If a boron silicide layer is formed, a hydrophilic surface appears, and if a boron silicide layer is not formed, a hydrophobic surface appears.
  • formation of a boron silicide layer can be prevented by selecting an appropriate boron concentration in the BSG film.
  • boron diffusion it is desirable to perform boron diffusion using a laminated film of a BSG film and an NSG film obtained by CVD film formation rather than vapor phase diffusion.
  • vapor phase diffusion it is difficult to control the concentration of the BSG film, and a boron-rich layer is easily formed.
  • adjust the supply timing such as supplying a boron-containing gas for diffusion when the temperature rises to an appropriate temperature in the step of heating the substrate. It is necessary to devise measures such as increasing the boron concentration in the gas or lightly oxidizing the surface by adding a small amount of oxygen.
  • the boron concentration in the CVD BSG film 12 is 0.5 wt% to 3 wt%. If the boron concentration in the BSG film 12 exceeds 3 wt%, the surface of the p-type single crystal silicon substrate 11 becomes a hydrophilic surface, and good cell characteristics cannot be obtained. On the other hand, unless the boron concentration in the BSG film 12 is less than 0.5 wt%, desired boron diffusion cannot be performed on the surface of the p-type single crystal silicon substrate 11.
  • the boron concentration of the vapor phase diffusion BSG film is generally 5 wt% or more.
  • the BSG film 12 and the NSG film 13 also circulate around the film formation surface, so that boron is also diffused to the portion where the BSG film 12 has circulated.
  • the wraparound film and the boron diffusion layer formed by the wrapping BSG film 12 are removed by etching when the texture 11T is formed.
  • stage S5 in FIG. 3 and step S105 in FIG. 4 in order to form a pn junction, phosphorus (P) is diffused by vapor phase diffusion on the texture 11T surface on the light receiving surface 11A side to form an n-type diffusion layer. 15 is formed.
  • the BSG film 12 and the NSG film 13 exhibit the function of a diffusion mask.
  • the PSG (Phospho Silicate Glass) film formed on the light receiving surface 11A side in the diffusion step is removed.
  • the BSG film 12 and the NSG film 13 can withstand the PSG film removal after the diffusion.
  • a BSG film and an NSG film which are oxide films formed by a CVD method, have a higher etching rate than a thermal oxide film formed by thermal oxidation, but BSG formed by the manufacturing process of the solar cell of the first embodiment. Since the film 12 and the NSG film 13 have undergone an annealing process at the time of boron diffusion, the etching rate becomes comparable to that of the thermal oxide film, and remains without being removed even after the PSG film is removed.
  • an antireflection film 16 made of a silicon nitride film is formed on the light receiving surface 11A side by CVD.
  • the light receiving surface electrode 17 and the back electrode 18 are formed on the light receiving surface 11A and the back surface 11B by printing.
  • step S108 in FIG. 4 After printing the light-receiving surface electrode 17 and the back surface electrode 18, heat treatment is performed, and as shown in step S108 in FIG. 4, the light-receiving surface electrode 17 contacts the n-type diffusion layer 15 and the back surface electrode 18 is p + type by fire-through. A contact is formed in contact with the diffusion layer 14 to complete the solar cell shown in FIGS.
  • the shape of the back electrode 18 is not particularly specified, and may be determined according to the thicknesses of the BSG film 12 and the NSG film 13. If thinly fabricating the NSG film 13, the back electrode 18, after printing form with silver aluminum (AgAl) paste, fire-through that is, through the BSG film 12 and the NSG film 13 by heat treatment, p + -type The diffusion layer 14 can be contacted.
  • FIG. 5 is a diagram showing a modification of the solar cell of the first embodiment. If the NSG film 13 is thick and difficult to fire through, the modified solar cell 20 is opened in the BSG film 12 and the NSG film 13 with a laser as shown in FIG.
  • the back electrode 18 is formed by printing in the same manner as the solar cell 10 of the first embodiment.
  • FIG. 6 is a comparison diagram of the open circuit voltage Voc and the short-circuit photocurrent density Jsc of the cells of the solar battery of the first embodiment and the solar battery of the comparative example.
  • the open circuit voltage Voc is a voltage when the current flowing to the outside is 0 A
  • the short-circuit photocurrent density Jsc is a current when the voltage applied to the outside is 0 V.
  • FIG. 6 compares the presence or absence of the texture on the back surface and the difference in the passivation film on the back surface.
  • PECVD-SiN which is a silicon nitride film formed by plasma CVD (Plasma Enhanced Chemical Vapor Deposition: PECVD)
  • PECVD Plasma Enhanced Chemical Vapor Deposition
  • FIG. 7 is a diagram showing the internal quantum efficiency (Internal Quantum Efficiency) of the solar cell of the first embodiment.
  • FIG. 8 is a diagram showing the internal quantum of the solar cell using the current plasma CVD silicon nitride for the passivation film on the back surface. It is a figure which shows efficiency. 7 and 8 both show the internal quantum efficiency of the Al-BSF cell as a comparison object.
  • the internal quantum efficiency is the ratio between the carriers generated by light irradiation and the extracted current, and can be regarded as the sensitivity of the solar cell.
  • FIG. 8 is a diagram showing the internal quantum efficiency (Internal Quantum Efficiency) of the solar cell of the first embodiment.
  • FIG. 8 is a diagram showing the internal quantum of the solar cell using the current plasma CVD silicon nitride for the passivation film on the back surface. It is a figure which shows efficiency. 7 and 8 both show the internal quantum efficiency of the Al-BSF cell as a comparison object.
  • the internal quantum efficiency is the ratio between the carriers generated
  • curve A1 indicates that there is no back surface texture when the laminated film of the BSG film 12 and NSG film 13 of Embodiment 1 is used as a passivation film
  • curve A2 indicates that there is a back surface texture
  • curve P1 indicates a comparison.
  • curve P2 indicates that there is a back surface texture
  • curve B indicates a case where Al-BSF is used for the back surface passivation film Pa.
  • the short wavelength sensitivity is lower than that of the Al-BSF cell, but this is influenced by the phosphorus diffusion on the light receiving surface 11A side.
  • the sheet resistance tends to be lower in the case where there is a laminated film of BSG film 12 and NSG film 13 or PECVD-SiN on the back surface 11B than in the case where there is no film.
  • phosphorus diffusion was performed on the bare p-type single crystal silicon substrate 11 on which no film was formed under the condition that the sheet resistance was 65 ⁇ / ⁇ . The sheet resistance was about. The cause is unknown, but the short wavelength sensitivity can be dealt with by adjusting the diffusion condition and is irrelevant to the passivation characteristics of the back surface 11B. The short wavelength sensitivity can be improved by selecting an appropriate value for the sheet resistance.
  • the BSG film and the NSG film are stacked on at least a part of the first surface which is one surface of the p-type single crystal silicon substrate, and heat treatment is performed.
  • a comb electrode or a point contact structure in which contact is made by forming a contact hole can be used as the back electrode.
  • a comb electrode using a silver aluminum (AgAl) paste it is difficult to form an Al—Si alloy, and warpage can be suppressed. For this reason, it is possible to reduce the thickness of the substrate.
  • the point contact structure the area of the Al—Si alloy is reduced, so that the thickness of the substrate can be reduced.
  • FIG. 9 is a cross-sectional view showing solar cell 30 of the second embodiment.
  • FIG. 10 is a process cross-sectional view illustrating the manufacturing process of the solar cell of the second embodiment.
  • FIG. 11 is a flowchart showing manufacturing steps of the solar cell of the second embodiment.
  • the solar cell using the p-type single crystal silicon substrate 11 in which the pn junction is arranged on the light receiving surface 11A side has been described, but in the second embodiment, the p-type single crystal silicon substrate 11 is used, A solar cell 30 having a pn junction on the back surface 11B side will be described.
  • the BSG film 12 and the NSG film 13 are on the light receiving surface 11A side, the BSG film 12 and the NSG film 13 must have a role as the antireflection film 16, and the BSG film 12 and the NSG film 13 It is necessary to adjust the film thickness. More specifically, it is necessary to adjust the film thickness including the film thickness ratio of the BSG film 12 and the NSG film 13 and the total film thickness so that the reflectance at 600 nm at which the sunlight spectrum is maximized is minimized.
  • the composition of the antireflection film and the passivation film 16P on the light receiving surface 11A side and the back surface 11B side is different from that of the diffusion layer on the light receiving surface 11A side and the back surface 11B side. Is substantially the same as the method for manufacturing the solar cell of the first embodiment except that is reversed.
  • the antireflection film is composed of a laminated film of the BSG film 12 and the NSG film 13.
  • a p-type single crystal silicon substrate 11 is prepared as shown in stage S1 of FIG. 10, and a p-type single crystal silicon substrate is etched by etching in a damaged layer removing step S101 shown in FIG. 11 Remove the damage layer on the surface.
  • a BSG film 12 serving as a diffusion source and a cap layer are formed on the light receiving surface 11A side of the p-type single crystal silicon substrate 11.
  • the NSG film 13 is laminated and formed.
  • the p-type single crystal silicon substrate 11 is annealed to diffuse boron in the BSG film 12 into the p-type single crystal silicon substrate 11, and to receive the light receiving surface.
  • a p + -type diffusion layer 14 is formed on the surface layer on the 11A side.
  • a small amount of POCl 3 and O 2 may be allowed to flow during annealing or cooling.
  • stage S5 in FIG. 10 and step S105S in FIG. 11 in order to form a pn junction, P (phosphorus) is diffused by vapor phase diffusion into the textured surface on the back surface 11B side to form the n-type diffusion layer 15 Form.
  • the BSG film 12 and the NSG film 13 exhibit the function of a diffusion mask.
  • the PSG film formed on the back surface 11B side in the diffusion step is removed.
  • the BSG film 12 and the NSG film 13 can withstand the PSG film removal after the diffusion.
  • a passivation film 16P made of a silicon nitride film is formed by CVD.
  • the light receiving surface electrode 17 and the back surface electrode 18 are formed by printing.
  • step S108 of FIG. 11 after the light-receiving surface electrode 17 and the back surface electrode 18 are printed, heat treatment is performed, and contacts are formed by fire-through to complete the solar cell 30 of the second embodiment shown in FIG. To do.
  • the process is started from the removal of the damaged layer as in FIG. 3, but the damaged layer may be removed by texture etching. In this case, there is no change in the other processes except that the texture 11T is formed on the light receiving surface 11A. As shown in FIG. 10, when the damaged layer is simply removed, the texture 11T is not formed on the light receiving surface 11A side. In that case, an alternative technique for preventing reflection, such as using an antireflection film, is used.
  • solar cell 30 of Embodiment 2 it goes without saying that manufacturing workability is good, and a laminated film having high passivation properties is used as an antireflection film and a passivation film on the light receiving surface side, and NSG.
  • the interface between the film 13 and the BSG film 12 is also reflective and scattering. Therefore, according to the solar cell 30 of Embodiment 2, the light collection rate and the internal quantum efficiency are improved, and a solar cell with high conversion efficiency can be obtained.
  • a thin solar cell without warping can be obtained. In the case of a thin solar cell, whether or not the interface between the passivation film and the semiconductor substrate or the semiconductor layer is clean often affects the characteristics. Since one surface of the single crystal silicon substrate 11 is covered, a clean interface can be maintained.
  • Embodiment 3 FIG.
  • the cells using the p-type single crystal silicon substrate 11 have been described. However, these cells are naturally applicable to cells using an n-type silicon substrate.
  • boron diffusion is performed using a laminated film of a BSG film and an NSG film, and the BSG film used as the diffusion source is used as a passivation film for the boron diffusion layer.
  • the BSG film and the NSG film are on the light receiving surface side, it is necessary that the BSG film and the NSG film have a role of an antireflection film. It is necessary to adjust the film thickness, surface state, and film quality of the NSG film.
  • Embodiment 4 FIG. Next, the solar cell of Embodiment 4 is demonstrated.
  • the light receiving surface side electrode and the back surface electrode are respectively disposed on the light receiving surface that is the first main surface and the back surface that is the second main surface of the substrate constituting the solar battery cell.
  • the lamination of the BSG film and the NSG film is also applied to boron diffusion in a so-called IBC (Interdigitated Back Contact) cell in which electrodes of both electrodes are arranged on the second surface 11b which is the back surface of the solar cell.
  • IBC Interdigitated Back Contact
  • a membrane can be applied.
  • 12 is a cross-sectional view showing the solar cell of the fourth embodiment using the IBC cell structure, FIG.
  • FIG. 13 is a process cross-sectional view showing the manufacturing process of the solar cell of the fourth embodiment
  • FIG. 14 is the fourth embodiment. It is a flowchart which shows the manufacturing process of this solar cell.
  • an n-type single crystal silicon substrate 11n is used, an n-type diffusion layer 15 is formed on part of the first surface 11a side and the second surface 11b side, and the first A p + -type diffusion layer 14 is formed on a part of the second surface 11b.
  • a first electrode 17R and a second electrode 18S are formed on the back surface 11B of the solar cell.
  • the laminated film of the BSG film 12 and the NSG film 13 is formed on the surface excluding the light receiving portion. That is, a part of the back surface 11 ⁇ / b> B also forms a pn junction with the n-type diffusion layer 15 to form a light receiving portion.
  • a feature of solar cell 40 of the fourth embodiment is that p + -type diffusion layer 14, that is, a laminated film of BSG film 12 and NSG film 13 used for forming the boron diffusion layer is used as a passivation film for the boron diffusion layer.
  • an n-type single crystal silicon substrate 11n is prepared as shown in the stage S1 of FIG. 13, and the n-type single crystal silicon substrate is etched by etching in the damage layer removing step S101 shown in FIG. The damage layer on the 11n surface is removed.
  • a BSG film 12 serving as a diffusion source is formed on a part on the second surface 11b side of the n-type single crystal silicon substrate 11n by the CVD apparatus.
  • the NSG film 13 as a cap layer is formed by being laminated.
  • a mask is formed on a part of the second surface 11b side so that the BSG film 12 and the NSG film 13 are not formed.
  • n-type single crystal silicon substrate 11n is annealed, and boron in BSG film 12 is changed to n-type single crystal silicon substrate 11n.
  • a p + -type diffusion layer 14 is selectively formed on a part of the second surface 11b side by diffusion.
  • the entire surface on the first surface 11a side and the second surface are formed using the BSG film 12 and NSG film 13 on the first surface 11a side as an etching mask.
  • the texture 11T is formed on a part of the surface 11b side.
  • stage S5 in FIG. 13 and step S105SS in FIG. 14 in order to form a pn junction, phosphorus is diffused in the texture surfaces on both sides to form the n-type diffusion layer 15.
  • the BSG film 12 and the NSG film 13 function as a diffusion mask.
  • the PSG film formed on the second surface 11b side in the diffusion step is removed.
  • the BSG film 12 and the NSG film 13 can withstand the PSG film removal after the diffusion.
  • an antireflection film 16 made of a silicon nitride film is formed by CVD.
  • the first electrode 17R and the second electrode 18S are formed by printing as shown in the stage S7 in FIG. 13 and the step S107S in FIG.
  • the NSG film 13 or the antireflection film 16 is thickly stacked on both the first surface 11a side and the second surface 11b side, the film remaining on the second surface 11b until the time of electrode formation is thick. Difficult to fire through.
  • the BSG film 12 and the NSG film 13 are opened with a laser, the contact hole h is formed, the point contact is formed, and then the same as in the solar cell of the first embodiment.
  • the first electrode 17R is formed by printing.
  • FIGS. 12 and 13 are schematic views assuming the use of the n-type single crystal silicon substrate 11n, but a substrate such as a p-type single crystal silicon substrate may be used. In that case, as shown in the first to third embodiments, some process adjustment is required.
  • a p-type single crystal silicon substrate is used as the substrate constituting the solar cell.
  • p-type silicon tends to have a reduced lifetime due to metal impurities, and thus special attention must be paid to contamination. Therefore, the process of removing the laminated film of the BSG film and NSG film used as the diffusion source and forming another passivation film again makes the process complicated and may contaminate the substrate. It leads to increase in sex. Therefore, using the laminated film of the BSG film and the NSG film used as the diffusion source is also effective in reducing the possibility of substrate contamination.
  • boron is used as the first conductivity type element used as the impurity.
  • the present invention is not limited to boron, and n-type impurities such as phosphorus are used as the first conductivity type element. It is also possible to apply.
  • a phosphorus-containing film such as a PSG film formed by a CVD method is used, but a coating film may be used when the impurity concentration can be controlled.
  • the configuration described in the above embodiment shows an example of the contents of the present invention, and can be combined with another known technique, and can be combined with other configurations without departing from the gist of the present invention. It is also possible to omit or change the part.

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  • Photovoltaic Devices (AREA)

Abstract

L'invention concerne une batterie solaire pourvue d'un film de passivation (Pa) qui comprend un film stratifié présentant : une couche de diffusion de type p+ (14) qui est disposée sur une surface arrière (11B) d'un substrat de silicium monocristallin de type p (11) et contient du bore à une concentration supérieure à la concentration en impuretés du substrat de silicium monocristallin de type p (11), le bore étant un élément d'un premier type d'électroconduction ; un film BSG (12), qui est une première couche de verre qui est stratifiée sur la surface arrière (11B) en contact avec la couche de diffusion de type p+ (14) et contient du bore et du silicium ; et un film NSG (13), qui est une seconde couche de verre qui est stratifiée sur le film BSG (12) et contient du silicium, mais pas de bore. En outre, une couche de diffusion de type n (15) est disposée sur la surface arrière (11B) ou sur une surface de réception de lumière (11A).
PCT/JP2016/087274 2016-12-14 2016-12-14 Batterie solaire et procédé de fabrication de batterie solaire Ceased WO2018109878A1 (fr)

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JP2025503057A (ja) * 2022-03-25 2025-01-30 ジァンスー ルネルギー センチュリー フォウトウヴォルテイク テクノロジー カンパニー リミテッド 低コストの接触パッシベーション全裏面電極太陽電池及びその製造方法
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JP7730101B1 (ja) * 2024-06-21 2025-08-27 Ｇｍｇ Ｔｒａｄｉｎｇ株式会社 太陽電池セル

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