WO2009157052A1 - Procédé de fabrication d’un système photovoltaïque - Google Patents

Procédé de fabrication d’un système photovoltaïque Download PDF

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Publication number
WO2009157052A1
WO2009157052A1 PCT/JP2008/061410 JP2008061410W WO2009157052A1 WO 2009157052 A1 WO2009157052 A1 WO 2009157052A1 JP 2008061410 W JP2008061410 W JP 2008061410W WO 2009157052 A1 WO2009157052 A1 WO 2009157052A1
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diffusion layer
photovoltaic device
oxide film
forming step
manufacturing
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PCT/JP2008/061410
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English (en)
Japanese (ja)
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濱本　哲
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三菱電機株式会社
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Priority to PCT/JP2008/061410 priority Critical patent/WO2009157052A1/fr
Publication of WO2009157052A1 publication Critical patent/WO2009157052A1/fr

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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L31/00—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
    • H01L31/18—Processes or apparatus specially adapted for the manufacture or treatment of these devices or of parts thereof
    • H01L31/1804—Processes or apparatus specially adapted for the manufacture or treatment of these devices or of parts thereof comprising only elements of Group IV of the Periodic Table
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L31/00—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
    • H01L31/04—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof adapted as photovoltaic [PV] conversion devices
    • H01L31/06—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof adapted as photovoltaic [PV] conversion devices characterised by potential barriers
    • H01L31/068—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof adapted as photovoltaic [PV] conversion devices characterised by potential barriers the potential barriers being only of the PN homojunction type, e.g. bulk silicon PN homojunction solar cells or thin film polycrystalline silicon PN homojunction solar cells
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L31/00—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
    • H01L31/18—Processes or apparatus specially adapted for the manufacture or treatment of these devices or of parts thereof
    • H01L31/186—Particular post-treatment for the devices, e.g. annealing, impurity gettering, short-circuit elimination, recrystallisation
    • H01L31/1868—Passivation
    • 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 method for manufacturing a photovoltaic device.
  • an impurity having a conductivity type opposite to that of a semiconductor substrate is diffused on the surface of the substrate to form an impurity diffusion layer (hereinafter referred to as a diffusion layer), and a PN junction is formed. It forms (for example, refer patent document 1).
  • a diffusion layer an impurity diffusion layer
  • PN junction a PN junction
  • the impurity concentration (doping concentration) for determining the conduction level is higher.
  • the diffusion layer also functions as a part of an electrode for efficiently extracting the generated current to an external circuit, it is preferable that the dopant concentration is high from that viewpoint.
  • the crystal quality in a silicon semiconductor shows better characteristics as the concentration of impurities present therein is lower. If the dopant concentration is too high, the crystal quality as a semiconductor is greatly reduced and the recombination rate is increased, so that the photovoltaic power is reduced. Therefore, it is important to set the dopant concentration to an appropriate concentration while balancing these three.
  • a thermal diffusion method is often used for forming a diffusion layer.
  • the thermal diffusion method is a method in which a substance containing the element to be diffused is heated to a high temperature in contact with the substrate surface and penetrated into the solid using dissolution in the solid and movement by thermal vibration.
  • phosphorus (P) diffusion is often used.
  • the thermal diffusion method since the diffusion source is in contact with the surface, the dopant concentration in the outermost surface portion is extremely high, and in many cases, the solid solubility (the upper limit at which the element can be dissolved in the solid) Has reached. Such a portion has extremely poor characteristics as a semiconductor, and is a major factor for reducing the photovoltaic power.
  • the present invention has been made in view of the above, and an object of the present invention is to obtain a method for manufacturing a photovoltaic device capable of removing the outermost surface of a diffusion layer formed on the surface of a semiconductor substrate by a thermal diffusion method with good controllability. To do.
  • a method for manufacturing a photovoltaic device comprises diffusing impurities of a second conductivity type on the light incident surface side of a semiconductor substrate of a first conductivity type.
  • An oxide film forming step of forming an oxide film by oxidizing while containing conductive impurities and an oxide film removing step of removing the oxide film are included.
  • the second conductivity type impurity is dissolved.
  • the outermost surface portion which is included near the limit of the degree of crystallinity and is deteriorated, is oxidized and removed without re-diffusion of the impurity of the second conductivity type.
  • the outermost surface portion of the diffusion layer can be removed easily and with good controllability.
  • the resulting photovoltaic device can convert the captured optical energy into electrical energy with high current-voltage characteristics, improve the output characteristics of the photovoltaic device, and obtain a highly efficient photovoltaic device Has the effect of being able to.
  • FIG. 1-1 is a top view of the photovoltaic device.
  • FIG. 1-2 is a rear view of the photovoltaic device.
  • 1-3 is a cross-sectional view taken along the line AA of FIG. 1-2.
  • FIG. 2-1 is a perspective view schematically showing one example of a processing procedure of the manufacturing method of the photovoltaic device according to the first embodiment (No. 1).
  • FIG. 2-2 is a perspective view schematically showing one example of a processing procedure of the manufacturing method of the photovoltaic device according to the first embodiment (No. 2).
  • FIG. 2-3 is a perspective view schematically showing one example of a processing procedure of the manufacturing method of the photovoltaic device according to the first embodiment (No. 3).
  • FIG. 2-4 is a perspective view schematically showing one example of a processing procedure of the manufacturing method of the photovoltaic device according to the first embodiment (No. 4).
  • FIG. 2-5 is a perspective view schematically showing an example of a processing procedure of the manufacturing method of the photovoltaic device according to the first embodiment (No. 5).
  • FIG. 2-6 is a perspective view schematically showing one example of a processing procedure of the manufacturing method of the photovoltaic device according to the first embodiment (No. 6).
  • FIG. 3-1 is a sectional view schematically showing an example of a processing procedure of the manufacturing method of the photovoltaic device according to the first embodiment (No. 1).
  • FIG. 1 is a sectional view schematically showing an example of a processing procedure of the manufacturing method of the photovoltaic device according to the first embodiment (No. 1).
  • FIG. 3-2 is a sectional view schematically showing an example of a processing procedure of the manufacturing method of the photovoltaic device according to the first embodiment (No. 2).
  • FIG. 3-3 is a sectional view schematically showing one example of a processing procedure of the manufacturing method of the photovoltaic device according to the first embodiment (No. 3).
  • FIG. 3-4 is a sectional view schematically showing an example of a processing procedure of the manufacturing method of the photovoltaic device according to the first embodiment (part 4).
  • FIG. 3-5 is a sectional view schematically showing one example of a processing procedure of the manufacturing method of the photovoltaic device according to the first embodiment (No. 5).
  • FIG. 3-6 is a sectional view schematically showing one example of a processing procedure of the manufacturing method of the photovoltaic device according to the first embodiment (No. 6).
  • FIG. 4 is a diagram showing the relationship between the thickness of the oxide film and the oxidation treatment time at each heat treatment temperature.
  • FIG. 5 is a diagram showing the diffusion coefficient of phosphorus in silicon.
  • FIG. 6 is a diagram showing the solid solubility of phosphorus in silicon.
  • FIG. 7-1 is a perspective view schematically showing an example of a processing procedure of the method for manufacturing a photovoltaic device according to the second embodiment (No. 1).
  • FIG. 7-2 is a perspective view schematically showing an example of a processing procedure of the method for manufacturing a photovoltaic device according to the second embodiment (No. 2).
  • FIG. 1 is a perspective view schematically showing an example of a processing procedure of the method for manufacturing a photovoltaic device according to the second embodiment (No. 2).
  • FIG. 7-1 is a perspective view
  • FIG. 7-3 is a perspective view schematically showing one example of a processing procedure of the method for manufacturing a photovoltaic device according to the second embodiment (No. 3).
  • FIG. 7-4 is a perspective view schematically showing an example of a processing procedure of the method for manufacturing a photovoltaic device according to the second embodiment (part 4).
  • FIG. 7-5 is a perspective view schematically showing one example of a processing procedure of the manufacturing method of the photovoltaic device according to the second embodiment (No. 5).
  • FIG. 7-6 is a perspective view schematically showing an example of a processing procedure of the method for manufacturing a photovoltaic device according to the second embodiment (No. 6).
  • FIG. 7-3 is a perspective view schematically showing one example of a processing procedure of the method for manufacturing a photovoltaic device according to the second embodiment (No. 3).
  • FIG. 7-4 is a perspective view schematically showing an example of a processing procedure of the method for manufacturing a photovoltaic device according to the second embodiment (part 4).
  • FIG. 7-7 is a perspective view schematically showing one example of a processing procedure of the method for manufacturing a photovoltaic device according to the second embodiment (No. 7).
  • 7-8 is a perspective view schematically showing an example of a processing procedure of the method for manufacturing a photovoltaic device according to the second embodiment (No. 8).
  • FIG. FIG. 7-9 is a perspective view schematically showing an example of a processing procedure of the method for manufacturing a photovoltaic device according to the second embodiment (No. 9).
  • FIG. 7-10 is a perspective view schematically showing one example of a processing procedure of the method for manufacturing the photovoltaic device according to the second embodiment (No. 10).
  • FIG. 10 is a perspective view schematically showing one example of a processing procedure of the method for manufacturing the photovoltaic device according to the second embodiment (No. 10).
  • FIGS. 8-1 is sectional drawing which shows typically an example of the process sequence of the manufacturing method of the photovoltaic device by this Embodiment 2 (the 1).
  • FIG. 8-2 is a sectional view schematically showing an example of a processing procedure of the manufacturing method of the photovoltaic device according to the second embodiment (No. 2).
  • FIG. 8-3 is a sectional view schematically showing an example of a processing procedure of the manufacturing method of the photovoltaic apparatus according to the second embodiment (No. 3).
  • FIG. 8-1 is sectional drawing which shows typically an example of the process sequence of the manufacturing method of the photovoltaic device by this Embodiment 2 (the 1).
  • FIG. 8-2 is a sectional view schematically showing an example of a processing procedure of the manufacturing method of the photovoltaic device according to the second embodiment (No. 2).
  • FIG. 8-3 is a sectional view schematically showing an example of a processing procedure of the manufacturing method of the photovoltaic apparatus according to the second embodiment (No. 3).
  • FIGS. 8-4 is a sectional view schematically showing an example of a processing procedure of the manufacturing method of the photovoltaic apparatus according to the second embodiment (part 4).
  • FIG. 8-5 is a sectional view schematically showing an example of a processing procedure of the manufacturing method of the photovoltaic apparatus according to the second embodiment (No. 5).
  • FIGS. 8-6 is sectional drawing which shows typically an example of the process sequence of the manufacturing method of the photovoltaic device by this Embodiment 2 (the 6).
  • FIGS. 8-7 is sectional drawing which shows typically an example of the process sequence of the manufacturing method of the photovoltaic device by this Embodiment 2 (the 7).
  • FIGS. 8-8 is sectional drawing which shows typically an example of the process sequence of the manufacturing method of the photovoltaic device by this Embodiment 2 (the 8).
  • FIGS. 8-9 is sectional drawing which shows typically an example of the process sequence of the manufacturing method of the photovoltaic device by this Embodiment 2 (the 9).
  • FIGS. 8-10 is sectional drawing which shows typically an example of the process sequence of the manufacturing method of the photovoltaic device by this Embodiment 2 (the 10).
  • FIG. 8-11 is a sectional view schematically showing an example of a processing procedure of the manufacturing method of the photovoltaic device according to the second embodiment (No. 11).
  • Photovoltaic device 101 P-type silicon substrate 102 N-type diffusion layer 102a Outermost surface portion 102H High-concentration N-type diffusion layer 102L Low-concentration N-type diffusion layer 103 Silicon oxide film 109 Antireflection film 110 P + layer 111 Surface electrode 112 Grid electrode 113 Bus electrode 120 Back surface electrode 121 Back side extraction electrode 122 Back side current collecting electrode 131 Etching-resistant film 140a Texture structure formation region 140b Electrode formation region 141 Opening 142 Recess
  • FIGS. 1-1 to 1-3 are diagrams schematically showing an example of the overall configuration of the photovoltaic device
  • FIG. 1-1 is a top view of the photovoltaic device
  • FIG. 1 is a back view of the electromotive force device
  • FIG. 1-3 is a cross-sectional view taken along the line AA of FIG.
  • the photovoltaic device 100 includes a P-type silicon substrate (hereinafter also simply referred to as a silicon substrate) 101 as a semiconductor substrate, and an N-type impurity on one main surface (light-receiving surface) side of the P-type silicon substrate 101. And a P + layer 110 containing P-type impurities at a higher concentration than the silicon substrate 101 on the surface on the other main surface (back surface) side.
  • the photovoltaic device 100 includes an antireflection film 109 that prevents reflection of incident light on the light receiving surface of the photoelectric conversion layer, and a light receiving surface for locally collecting electricity generated by the photoelectric conversion layer.
  • the grid electrode 112 made of silver or the like provided, the bus electrode 113 made of silver or the like provided almost orthogonally to the grid electrode 112 for taking out the electricity collected by the grid electrode 112, and the photoelectric conversion layer
  • a back side extraction electrode 121 made of aluminum or the like provided on almost the entire back surface of the P-type silicon substrate 101 for the purpose of taking out electricity and reflecting incident light transmitted through the photoelectric conversion layer, and electricity generated in the back side extraction electrode 121
  • a back side collecting electrode 122 made of silver or the like for collecting current.
  • the grid electrode 112 and the bus electrode 113 on the light receiving surface side are combined, hereinafter, also referred to as the surface electrode 111, and the back side extraction electrode 121 and the back side collector electrode 122 on the back side are combined. Then, it is also referred to as a back electrode 120.
  • the photovoltaic device 100 configured in this way, sunlight is applied to the PN junction surface (the junction surface between the P-type silicon substrate 101 and the N-type diffusion layer 102) from the light-receiving surface side of the photovoltaic device 100. And holes and electrons are generated. Due to the electric field in the vicinity of the PN junction surface, the generated electrons move toward the N-type diffusion layer 102 and the holes move toward the P + layer 110. As a result, electrons are excessive in the N-type diffusion layer 102 and holes are excessive in the P + layer 110. As a result, photovoltaic power is generated.
  • This photovoltaic power is generated in a direction in which the PN junction is biased in the forward direction, the front electrode 111 connected to the N-type diffusion layer 102 becomes a negative pole, and the back electrode 120 connected to the P + layer 110 becomes a positive pole. Current flows in the external circuit that does not.
  • FIGS. 2-1 to 2-6 are perspective views schematically showing an example of the processing procedure of the manufacturing method of the photovoltaic device according to the first embodiment.
  • FIGS. 3-1 to 3-6 are It is sectional drawing which shows typically an example of the process sequence of the manufacturing method of the photovoltaic apparatus by this Embodiment 1.
  • a silicon substrate 101 is prepared (FIGS. 2-1 and 3-1). Here, it is assumed that a P-type polycrystalline silicon substrate that is most frequently used for consumer photovoltaic devices is used.
  • the silicon substrate 101 is manufactured by slicing a polycrystalline silicon ingot with a multi-wire saw and removing damage during slicing by wet etching using an acid or alkali solution.
  • the thickness of the silicon substrate 101 after removing the damage is 200 ⁇ m, and the dimensions are 150 mm ⁇ 150 mm.
  • a texture shape is formed simultaneously with or subsequent to the removal of damage. This is to provide an uneven shape on the surface of the silicon substrate 101 as a measure for efficiently absorbing light incident on the silicon substrate 101 inside.
  • the silicon substrate 101 after removing the damage is put into a thermal oxidation furnace, heated in an atmosphere of phosphorus (P) as an N-type impurity, and phosphorus is diffused at a high concentration on the surface of the silicon substrate 101, so that N-type diffusion is performed.
  • the layer 102 is formed (FIGS. 2-2 and 3-2).
  • phosphorus oxychloride (POCl 3 ) is used to form a phosphorus atmosphere and diffuse at 800 to 850 ° C.
  • the N-type diffusion layer 102 is controlled so that the sheet resistance is 30 to 80 ⁇ / ⁇ , preferably 40 to 60 ⁇ / ⁇ .
  • the phosphorus glass layer formed by heating in the presence of phosphorus oxychloride vapor is removed in a hydrofluoric acid solution.
  • the outermost surface portion 102a in the thickness range of about 10 nm from the surface of the N-type diffusion layer 102 has reached the limit or close to the limit of the solid solubility of phosphorus in the silicon substrate 101, and has characteristics as a semiconductor. This is a very bad part.
  • the silicon substrate 101 on which the N-type diffusion layer 102 is formed is put into an oxidation furnace in which a high-concentration ozone atmosphere can be introduced, and the outermost surface portion 102a of the N-type diffusion layer 102 is oxidized by taking in the phosphorus contained therein. (FIGS. 2-3 and 3-3).
  • a silicon oxide film 103 containing phosphorus is formed on the outermost surface of the N-type diffusion layer 102, but the lower portion remains the N-type diffusion layer 102.
  • the silicon thermal oxidation in this high-concentration ozone atmosphere is described in detail in Japanese Patent Application Laid-Open No. 2003-209108.
  • FIG. 4 is a diagram showing the relationship between the thickness of the oxide film and the oxidation treatment time at each heat treatment temperature. As shown in FIG. 4, for example, a thermal oxide film having a thickness of 10 nm can be formed in about 14 minutes at 500 ° C. and in about 9 minutes at 590 ° C.
  • FIG. 5 is a diagram showing the diffusion coefficient of phosphorus in silicon
  • FIG. 6 is a diagram showing the solid solubility of phosphorus in silicon.
  • the outermost surface portion 102a of the N-type diffusion layer 102 is in a state in which phosphorus is contained up to the solid solubility limit as shown in FIG. 6 by the diffusion treatment, but as shown in FIG.
  • the diffusion coefficient of phosphorus decreases rapidly as the temperature is low, and at a temperature of 700 ° C. or lower, preferably 600 ° C. or lower, which extends this graph, phosphorus can hardly move in the silicon crystal. Therefore, the oxidation of the silicon substrate (N-type diffusion layer 102) proceeds in such a manner that phosphorus is taken in along with the oxidation.
  • the outermost surface portion 102a to be removed can be changed to the silicon oxide film 103 while containing phosphorus.
  • the oxidation temperature is 300 to 700 ° C. where the diffusion coefficient of phosphorus is small and an oxidation rate of a certain level or more is obtained, preferably 400 to 600 ° C.
  • the thickness of the silicon oxide film 103 to be formed is 5 to 20 nm, Desirable is controlled in the range of 8 to 15 nm.
  • the silicon oxide film 103 on the outermost surface after oxidation is unnecessary and is removed (FIGS. 2-4 and 3-4).
  • Hydrofluoric acid dissolves the silicon oxide film, but does not dissolve the silicon crystal itself. Therefore, when this hydrofluoric acid is used, the dissolution reaction stops when the silicon oxide film 103 containing phosphorus on the outermost surface is removed, so that only the portion with poor crystallinity to be removed can be removed with good controllability.
  • the antireflection film 109 a SiN film is formed on the cell surface by plasma CVD (Chemical Vapor Deposition) method (FIGS. 2-5 and 3-5).
  • the film thickness and refractive index are set to values that most suppress light reflection. Note that two or more layers having different refractive indexes may be stacked as the antireflection film 109. Moreover, you may form by different film-forming methods, such as a sputtering method.
  • a paste mixed with aluminum is formed by screen printing on the entire surface of the back surface of the silicon substrate 101 other than the position where the back side collecting electrode 122 is formed, and the paste mixed with silver is formed at a predetermined position (back side collector) on the back surface of the silicon substrate 101.
  • the paste is mixed with silver on the surface of the silicon substrate 101 by the screen printing method.
  • the silicon substrate 101 is baked. For example, the firing process is performed at 760 ° C. in an air atmosphere, and the front electrode 111 is formed on the front surface and the back electrode 120 is formed on the back surface (FIGS. 2-6 and 3-6). At this time, the surface electrode 111 penetrates the antireflection film 109 and contacts the N-type diffusion layer 102 at the joint portion.
  • the N-type diffusion layer 102 can obtain a good resistive junction with the surface electrode 111.
  • aluminum diffuses from the paste mixed with aluminum formed on the back surface into the silicon substrate 101 to form the P + layer 110 having the BSF function on the back surface side of the silicon substrate 101 and used for forming the P + layer 110.
  • the missing aluminum in the paste is formed as the back side extraction electrode 121.
  • the photovoltaic device is manufactured through the above steps.
  • the heat treatment is performed in a high-concentration ozone atmosphere at a temperature of 700 ° C. or less at which phosphorus hardly diffuses. Only the outermost surface of the N-type diffusion layer 102 can be oxidized to form the silicon oxide film 103 containing phosphorus. Further, by etching this silicon oxide film 103 with hydrofluoric acid, only the silicon oxide film 103 can be etched without etching the P-type silicon substrate 101 (N-type diffusion layer 102). This has the effect that the portion of the N-type diffusion layer 102 having the highest phosphorus concentration and poor crystallinity can be removed easily and with good controllability.
  • the photovoltaic device 100 formed in this way has improved crystallinity at the outermost surface portion 102a of the N-type diffusion layer 102, so that a high photovoltaic power can be realized.
  • the output characteristics of the device 100 are improved, and the photovoltaic device 100 having high efficiency can be obtained.
  • the outermost surface portion 102a having poor crystallinity of the N-type diffusion layer 102 is removed, the efficiency is improved, and the photovoltaic device 100 to be manufactured contributes to the extension of the lifetime and the yield by the amount of addition. can do. As a result, the raw material can be reduced.
  • FIG. 7-1 to 7-11 are perspective views schematically showing an example of the processing procedure of the method for manufacturing a photovoltaic device according to the second embodiment.
  • FIGS. 8-1 to 8-11 are FIGS.
  • FIG. 5 is a cross-sectional view schematically showing an example of a processing procedure of the method for manufacturing a photovoltaic device according to the second embodiment.
  • FIGS. 7-1 to 8-11 for example, a part of the periphery of one grid electrode 112 of the photovoltaic device 100 of FIG. 1 is shown enlarged.
  • a P-type silicon substrate from which damage has been removed is prepared (FIGS. 7-1 and 8-1). Thereafter, the silicon substrate 101 after removal of the damage is put into a thermal oxidation furnace, heated in an atmosphere of phosphorus as an N-type impurity, and phosphorus is diffused at a high concentration on the surface of the silicon substrate 101, whereby a high-concentration N-type diffusion layer is formed.
  • 102H is formed (FIGS. 7-2 and 8-2).
  • phosphorus oxychloride is used to form a phosphorus atmosphere and diffused at 800 to 850 ° C.
  • the surface sheet resistance of the high concentration N-type diffusion layer 102H is controlled to be 30 to 60 ⁇ / ⁇ .
  • a film 131 having etching resistance (hereinafter referred to as an etching resistant film) 131 is formed on the high-concentration N-type diffusion layer 102H formed on one main surface (FIGS. 7-3 and 8-3).
  • the etching resistant film 131 is a material having resistance when the silicon substrate 101 is textured and etched later, and is a silicon nitride film (hereinafter, referred to as a SiN film), a silicon oxide (SiO 2 , SiO) film, a silicon oxynitride ( An SiON) film, an amorphous silicon ( réelle-Si) film, a diamond-like carbon film, a resin film, or the like can be used.
  • an SiN film having a thickness of 80 nm formed by plasma CVD is used as the etching resistant film 131.
  • the film thickness is 80 nm
  • an appropriate film thickness can be selected from the etching conditions at the time of texture / etching and the removability of the SiN film in the subsequent process.
  • an opening 141 that is a fine hole is formed in the texture structure forming region 140a on the etching resistant film 131 (FIGS. 7-4 and 8-4).
  • the surface of the underlying silicon substrate 101 (high-concentration N-type diffusion layer 102H) is exposed at the opening 141 portion.
  • the opening 141 is not formed in the electrode forming region 140b where the light incident side electrode (surface electrode) of the photovoltaic device 100 is to be formed without forming the texture structure.
  • the opening 141 can be formed by a laser irradiation method, a photolithography method used in a semiconductor process, or the like.
  • the vicinity of the surface of the silicon substrate 101 including the high-concentration N-type diffusion layer 102H is etched through the opening 141 opened in the etching resistant film 131 to form the recess 142 (FIGS. 7-5 and 8-5).
  • a concave portion 142 is formed on the surface of the silicon substrate 101 at the concentric position with the fine opening 141 as the center.
  • a mixed solution of hydrofluoric acid and nitric acid is used as an etching solution.
  • the mixing ratio is hydrofluoric acid 1: nitric acid 20: water 10.
  • the mixing ratio of the etching liquid can be changed to an appropriate mixing ratio depending on the desired etching rate and etching shape.
  • the high concentration N-type diffusion layer 102H in that portion is simultaneously removed. That is, of the surface of the recess 142 formed by this etching, the high concentration N-type diffusion layer 102H is formed on the substrate surface side, but no impurity is introduced in a deeper region.
  • the electrode formation region 140b where the surface electrode 111 is to be formed is in a state where the high-concentration N-type diffusion layer 102H remains. Further, as shown in FIGS. 7-5 and 8-5, the high-concentration N-type diffusion layer 102H can be left also in the portion between the adjacent recesses 142. Thus, the generated current is guided to the surface electrode 111 (grid electrode 112) through a low-resistance current path.
  • the silicon substrate 101 is again put into a thermal oxidation furnace and heated in the presence of phosphorus oxychloride vapor.
  • a low concentration N-type diffusion layer 102L in which phosphorus is diffused at a low concentration is formed on the surface of the recess 142 (FIGS. 7-7 and 8-7).
  • the diffusion temperature at this time is 800 to 850 ° C.
  • the high-concentration N-type diffusion layer 102H remains in the electrode formation region 140b at the time of the etching, the high-concentration N-type diffusion layer 102H remains almost as it is even if the low-concentration diffusion is performed again.
  • the high concentration N type diffusion layer 102H is removed during etching, and the low concentration N type diffusion layer 102L is formed on the surface of the concave portion 142.
  • the surface sheet resistance of the low concentration N-type diffusion layer 102L is controlled to be 60 to 150 ⁇ / ⁇ .
  • the phosphorus glass layer formed by heating in the presence of phosphorus oxychloride vapor is removed in a hydrofluoric acid solution. Thereafter, in this state, ozone oxidation is performed in the same manner as in the first embodiment, and the uppermost surface portions of the high-concentration N-type diffusion layer 102H and the low-concentration N-type diffusion layer 102L are oxidized including phosphorus. As a result, a silicon oxide film 103 containing phosphorus is formed on the outermost surfaces of the high-concentration N-type diffusion layer 102H and the low-concentration N-type diffusion layer 102L (FIGS. 7-8 and 8-8).
  • a high concentration N-type diffusion layer 102H is mainly provided below the portion where the electrode portion is provided, and a low concentration N-type diffusion layer 102L is provided at other portions. Therefore, as compared with the first embodiment, a structure that can suppress the influence of the outermost surface portion is employed. However, as long as the thermal diffusion method is taken, even the low-concentration N-type diffusion layer 102L contains phosphorus up to the solid solubility limit at the outermost surface portion, and the effect is avoided to some extent. Absent. Therefore, the output characteristics of the photovoltaic device 100 can be sufficiently improved with respect to the photovoltaic device 100 having the structure in which the concave portion 142 is formed as the texture structure.
  • the thickness to be oxidized may be smaller than that in the first embodiment because the structure capable of suppressing the influence of the outermost surface portion is used. Although it depends on the detailed structure including the surface electrode 111 and productivity, it is appropriate to control in the range of 5 to 15 nm.
  • the silicon oxide film 103 containing phosphorus at the outermost surface portions of the high-concentration N-type diffusion layer 102H and the low-concentration N-type diffusion layer 102L is removed using hydrofluoric acid to expose the silicon portion (FIG. 7- 9, FIG. 8-9), a SiN film as an antireflection film 109 is formed on the surface of the diffusion layer by a film forming method such as a plasma CVD method (FIGS. 7-10 and 8-10).
  • a paste mixed with aluminum is formed by screen printing on the entire surface of the back surface of the silicon substrate 101 other than the position where the back side collecting electrode 122 is formed, and the paste mixed with silver is formed at a predetermined position (back side collector) on the back surface of the silicon substrate 101.
  • the paste is mixed with silver on the surface of the silicon substrate 101 by the screen printing method.
  • a baking process is performed to form the back electrode 120 (the back side extraction electrode 121 and the back side current collecting electrode 122) and the front surface electrode 111 (the grid electrode 112 and the bus electrode 113).
  • the firing process is performed at 760 ° C. in an air atmosphere.
  • the surface electrode 111 penetrates the antireflection film 109 and contacts the high-concentration N-type diffusion layer 102H at the joint portion.
  • the high-concentration N-type diffusion layer 102H can obtain a good resistive junction with the surface electrode 111.
  • aluminum diffuses from the paste mixed with aluminum formed on the back surface into the silicon substrate 101 to form a P + layer 110 having a BSF function on the back surface side of the silicon substrate 101 and used for forming the P + layer 110.
  • the aluminum in the paste that did not exist becomes the back electrode 120 (FIGS. 7-11 and 8-11).
  • the photovoltaic device 100 is manufactured through the above steps.
  • This second embodiment can also obtain the same effects as those of the first embodiment.
  • the silicon substrate used in the first and second embodiments is a P-type silicon substrate, other than a reverse-conductivity type photovoltaic device or silicon substrate that forms a P-type diffusion layer using an N-type silicon substrate.
  • a photovoltaic device using this semiconductor substrate also has the same effect.
  • a polycrystalline silicon substrate is used as the substrate, it goes without saying that the same effect can be obtained by using a single crystal silicon substrate.
  • the thickness of the substrate is 200 ⁇ m is shown here, a substrate that can be self-supported, for example, thinned to about 50 ⁇ m can be used.
  • substrate was also 150 mm x 150 mm was shown, it cannot be overemphasized that the same effect is acquired even if it is larger or smaller than this.
  • the method for manufacturing a photovoltaic device according to the present invention is useful for a solar cell that generates power using sunlight.

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  • Engineering & Computer Science (AREA)
  • Computer Hardware Design (AREA)
  • Physics & Mathematics (AREA)
  • Condensed Matter Physics & Semiconductors (AREA)
  • Electromagnetism (AREA)
  • General Physics & Mathematics (AREA)
  • Microelectronics & Electronic Packaging (AREA)
  • Power Engineering (AREA)
  • Manufacturing & Machinery (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Chemical & Material Sciences (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Sustainable Development (AREA)
  • Photovoltaic Devices (AREA)

Abstract

Dans le procédé selon l’invention de fabrication d’un système photovoltaïque, la surface la plus à l’extérieur d’une couche diffusée formée à la surface d’un substrat semi-conducteur par un procédé de diffusion thermique est retirée avec un excellent contrôle.  Le procédé de fabrication comprend une étape de formation d’une couche diffusée de type N servant à former une couche diffusée de type N (102) en diffusant une impureté de type N sur le côté de la surface de lumière incidente d’un substrat de silicium de type P (101) ; une étape de formation de pellicule d’oxyde de silicium servant à former une pellicule d'oxyde de silicium (103) en oxydant la section de surface la plus à l’extérieur de la couche diffusée de type N (102) à une température à laquelle l’impureté de type N n’est pas diffusée tout en contenant l’impureté de type N diffusée dans la section de surface la plus à l’extérieur ; et une étape de retrait de la pellicule d’oxyde de silicium servant à retirer la  pellicule d’oxyde de silicium (103).
PCT/JP2008/061410 2008-06-23 2008-06-23 Procédé de fabrication d’un système photovoltaïque WO2009157052A1 (fr)

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WO2011132340A1 (fr) * 2010-04-21 2011-10-27 三菱電機株式会社 Procédé de fabrication d'un substrat à faible réflexion, procédé de fabrication d'un dispositif photovoltaïque, et dispositif photovoltaïque
WO2011145479A1 (fr) * 2010-05-18 2011-11-24 三菱電機株式会社 Procédé de rugosification d'un substrat, et procédé de fabrication d'un appareil à force motrice photovoltaïque
WO2012117558A1 (fr) * 2011-03-03 2012-09-07 三菱電機株式会社 Dispositif photovoltaïque, procédé de fabrication correspondant et module photovoltaïque
RU2586265C2 (ru) * 2014-07-04 2016-06-10 Федеральное Государственное Бюджетное Образовательное Учреждение Высшего Профессионального Образования "Дагестанский Государственный Технический Университет" (Дгту) Способ осаждения тонких пленок на поверхности подложек для изготовления солнечных элементов
CN114242836A (zh) * 2021-12-10 2022-03-25 环晟光伏(江苏)有限公司 一种提升硅片转换效率的预处理方法
US11735678B2 (en) * 2019-03-29 2023-08-22 Maxeon Solar Pte. Ltd. Solar cells having hybrid architectures including differentiated p-type and n-type regions with offset contacts

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WO2011132340A1 (fr) * 2010-04-21 2011-10-27 三菱電機株式会社 Procédé de fabrication d'un substrat à faible réflexion, procédé de fabrication d'un dispositif photovoltaïque, et dispositif photovoltaïque
JP5430751B2 (ja) * 2010-04-21 2014-03-05 三菱電機株式会社 低反射基板の製造方法、および光起電力装置の製造方法
WO2011145479A1 (fr) * 2010-05-18 2011-11-24 三菱電機株式会社 Procédé de rugosification d'un substrat, et procédé de fabrication d'un appareil à force motrice photovoltaïque
JP5377762B2 (ja) * 2010-05-18 2013-12-25 三菱電機株式会社 基板の粗面化方法
DE112012001067T5 (de) 2011-03-03 2013-11-28 Mitsubishi Electric Corp. Photovoltaikvorrichtung, Herstellungsverfahren für diese, und Photovoltaikmodul
CN103370795A (zh) * 2011-03-03 2013-10-23 三菱电机株式会社 光伏装置及其制造方法、光伏模块
KR20130111605A (ko) 2011-03-03 2013-10-10 미쓰비시덴키 가부시키가이샤 광기전력 장치 및 그 제조 방법, 광기전력 모듈
WO2012118201A1 (fr) * 2011-03-03 2012-09-07 三菱電機株式会社 Dispositif photovoltaïque, son procédé de fabrication et module photovoltaïque
WO2012117558A1 (fr) * 2011-03-03 2012-09-07 三菱電機株式会社 Dispositif photovoltaïque, procédé de fabrication correspondant et module photovoltaïque
JP5622925B2 (ja) * 2011-03-03 2014-11-12 三菱電機株式会社 光起電力装置およびその製造方法、光起電力モジュール
US9252305B2 (en) 2011-03-03 2016-02-02 Mitsubishi Electric Corporation Photovoltaic device, manufacturing method thereof, and photovoltaic module
RU2586265C2 (ru) * 2014-07-04 2016-06-10 Федеральное Государственное Бюджетное Образовательное Учреждение Высшего Профессионального Образования "Дагестанский Государственный Технический Университет" (Дгту) Способ осаждения тонких пленок на поверхности подложек для изготовления солнечных элементов
US11735678B2 (en) * 2019-03-29 2023-08-22 Maxeon Solar Pte. Ltd. Solar cells having hybrid architectures including differentiated p-type and n-type regions with offset contacts
CN114242836A (zh) * 2021-12-10 2022-03-25 环晟光伏(江苏)有限公司 一种提升硅片转换效率的预处理方法

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