WO2014010745A1 - 太陽電池素子及びその製造方法 - Google Patents

太陽電池素子及びその製造方法 Download PDF

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WO2014010745A1
WO2014010745A1 PCT/JP2013/069224 JP2013069224W WO2014010745A1 WO 2014010745 A1 WO2014010745 A1 WO 2014010745A1 JP 2013069224 W JP2013069224 W JP 2013069224W WO 2014010745 A1 WO2014010745 A1 WO 2014010745A1
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passivation layer
solar cell
semiconductor substrate
cell element
forming
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PCT/JP2013/069224
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English (en)
French (fr)
Japanese (ja)
Inventor
明博 織田
吉田　誠人
野尻　剛
倉田　靖
田中　徹
修一郎 足立
剛 早坂
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日立化成株式会社
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Priority to JP2014524903A priority Critical patent/JPWO2014010745A1/ja
Priority to CN201380036463.7A priority patent/CN104428901B/zh
Publication of WO2014010745A1 publication Critical patent/WO2014010745A1/ja

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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
    • H01L31/02—Details
    • H01L31/0216—Coatings
    • H01L31/02161—Coatings for devices characterised by at least one potential jump barrier or surface barrier
    • H01L31/02167—Coatings for devices characterised by at least one potential jump barrier or surface barrier for 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
    • H01L31/02—Details
    • H01L31/0224—Electrodes
    • H01L31/022408—Electrodes for devices characterised by at least one potential jump barrier or surface barrier
    • H01L31/022425—Electrodes for devices characterised by at least one potential jump barrier or surface barrier for 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
    • H01L31/04—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
    • H01L31/1804—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
    • 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 element and a manufacturing method thereof.
  • a p-type silicon substrate having a texture structure formed on the light-receiving surface side is prepared so as to promote the light confinement effect and increase the efficiency, and then in a mixed gas atmosphere of phosphorus oxychloride (POCl 3 ), nitrogen and oxygen
  • POCl 3 phosphorus oxychloride
  • the n-type diffusion layer is uniformly formed on the surface of the p-type silicon substrate by performing several tens of minutes at 800 ° C. to 900 ° C.
  • n-type diffusion layers are formed not only on the light-receiving surface of the p-type silicon substrate, but also on the side and back surfaces.
  • n-type diffusion layer formed on the side surface needs to be converted into a p + -type diffusion layer.
  • an aluminum paste containing aluminum powder, glass frit, liquid medium, organic binder, etc. is applied to the whole or a part of the back surface, and this is heat-treated (fired) to form an aluminum electrode, thereby forming an n-type diffusion.
  • the ohmic contact is obtained at the same time as making the layer a p + -type diffusion layer.
  • the aluminum electrode formed from the aluminum paste has low conductivity. Therefore, in order to reduce the sheet resistance, the aluminum electrode formed on the entire back surface usually must have a thickness of about 10 ⁇ m to 20 ⁇ m after heat treatment (firing). Furthermore, since the thermal expansion coefficient differs greatly between silicon and aluminum, a large internal stress is generated in the silicon substrate during the heat treatment (firing) and cooling in the silicon substrate on which the aluminum electrode is formed, and the grain boundary Cause damage, crystal defect growth and warpage.
  • an aluminum paste is applied to a part of the surface opposite to the light receiving surface of the silicon substrate (hereinafter also referred to as “back surface”) to partially form a p + -type diffusion layer and an aluminum electrode.
  • a point contact technique has been proposed (see, for example, Japanese Patent No. 3107287).
  • a SiO 2 film or the like has been proposed as a backside passivation layer (see, for example, Japanese Patent Application Laid-Open No. 2004-6565).
  • As a passivation effect by forming such a SiO 2 film there is an effect of terminating the dangling bonds of silicon atoms in the back surface layer portion of the silicon substrate and reducing the surface state density causing recombination.
  • Such a passivation effect is generally called a field effect, and an aluminum oxide (Al 2 O 3 ) film or the like has been proposed as a material having a negative fixed charge (see, for example, Japanese Patent No. 4767110).
  • Such a passivation layer is generally formed by a method such as an ALD (Atomic Layer Deposition) method or a CVD (Chemical Vapor Deposition) method (for example, Journal of Applied Physics, 104 (2008), 113703-1). 113703-7).
  • a solar cell with high efficiency has been proposed by changing the concentration of the impurity diffusion layer between the region directly under the electrode and other regions (for example, E. Lee et. Al. , “Exceeding” 19% “efficient” 6 ”inch” screen “printed” crystalline, “silicon” solar “cells” with “selective“ emitter ”, Revewable Energy, 42 (2012) 95)
  • the present invention has been made in view of the above-described conventional problems, and provides a solar cell element that has excellent conversion efficiency and suppresses deterioration of solar cell characteristics over time, and a method for manufacturing the solar cell element. Let it be an issue.
  • the p-type diffusion region and the n-type diffusion region are arranged apart from each other, each having a plurality of rectangular portions having a short side and a long side,
  • the plurality of rectangular portions that the p-type diffusion region has are arranged such that the direction of the long sides of the plurality of rectangular portions is along the direction of the long sides of the plurality of rectangular portions that the n-type diffusion region has,
  • the solar cell element according to ⁇ 2> wherein the plurality of rectangular portions included in the p-type diffusion region and the plurality of rectangular portions included in the n-type diffusion region are alternately arranged.
  • ⁇ 4> The solar cell element according to ⁇ 2> or ⁇ 3>, which is a back contact type solar cell element.
  • ⁇ 6> The solar cell element according to ⁇ 5>, wherein the first impurity diffusion layer and the second impurity diffusion layer are an n-type diffusion layer or a p-type diffusion layer.
  • ⁇ 7> The solar cell element according to any one of ⁇ 1> to ⁇ 6>, wherein the passivation layer includes aluminum oxide having an amorphous structure.
  • ⁇ 8> The solar cell element according to any one of ⁇ 1> to ⁇ 7>, wherein a density of the passivation layer is 1.0 g / cm 3 to 8.0 g / cm 3 .
  • ⁇ 9> The solar cell element according to any one of ⁇ 1> to ⁇ 8>, wherein an average thickness of the passivation layer is 5 nm to 50 ⁇ m.
  • the passivation layer is a heat-treated product of a composition for forming a passivation layer containing an organoaluminum compound.
  • organoaluminum compound includes an organoaluminum compound represented by the following general formula (I).
  • each R 1 independently represents an alkyl group having 1 to 8 carbon atoms.
  • n represents an integer of 0 to 3.
  • X 2 and X 3 each independently represent an oxygen atom or a methylene group.
  • R 2 , R 3 and R 4 each independently represents a hydrogen atom or an alkyl group having 1 to 8 carbon atoms.
  • each R 1 is independently an alkyl group having 1 to 4 carbon atoms.
  • n is an integer of 1 to 3
  • R 4 is independently a hydrogen atom or an alkyl group having 1 to 4 carbon atoms.
  • composition for forming a passivation layer is any one of ⁇ 11> to ⁇ 13>, wherein the content of the organoaluminum compound represented by the general formula (I) is 0.5% by mass to 80% by mass
  • composition for forming a passivation layer is any one of ⁇ 11> to ⁇ 13>, wherein the content of the organoaluminum compound represented by the general formula (I) is 0.1% by mass to 50% by mass
  • liquid medium includes at least one selected from the group consisting of a terpene solvent, an ester solvent, an ether solvent, and an alcohol solvent.
  • composition for forming a passivation layer further contains an organic compound represented by the following general formula (II).
  • ⁇ 19> forming a light receiving surface electrode on a light receiving surface of a semiconductor substrate having a light receiving surface and a back surface opposite to the light receiving surface; Forming a back electrode on the back surface of the semiconductor substrate; Forming a composition layer by applying a passivation layer forming composition containing an organoaluminum compound on the back surface of the semiconductor substrate; and The method for producing a solar cell element according to any one of ⁇ 1> and ⁇ 7> to ⁇ 18>, further comprising a step of heat-treating the composition layer to form a passivation layer containing aluminum oxide.
  • the p of the semiconductor substrate having a light receiving surface and a back surface opposite to the light receiving surface, and having a p-type diffusion region containing a p-type impurity and an n-type diffusion region containing an n-type impurity on the back surface.
  • ⁇ 21> forming a region of a first impurity diffusion layer in a part of the light receiving surface of a semiconductor substrate having a light receiving surface and a back surface opposite to the light receiving surface; Forming a region of a second impurity diffusion layer having an impurity concentration lower than that of the first impurity diffusion layer on the light receiving surface; Forming a light-receiving surface electrode on the first impurity diffusion layer; Forming a back electrode on the back surface; Providing a passivation layer forming composition containing an organoaluminum compound on at least one of the light receiving surface and the back surface to form a composition layer; and The method for producing a solar cell element according to any one of ⁇ 5> to ⁇ 18>, further comprising a step of heat-treating the composition layer to form a passivation layer containing aluminum oxide.
  • ⁇ 22> The method for producing a solar cell element according to any one of ⁇ 19> to ⁇ 21>, wherein the heat treatment is performed at a temperature of 400 ° C. or higher.
  • ⁇ 23> The step according to any one of ⁇ 19> to ⁇ 22>, wherein the step of forming the composition layer includes applying the passivation layer forming composition to a semiconductor substrate by a screen printing method.
  • a battery element manufacturing method A battery element manufacturing method.
  • the present invention it is possible to provide a solar cell element that has excellent conversion efficiency and suppresses deterioration of solar cell characteristics over time, and a method for manufacturing the solar cell element.
  • the term “process” is not limited to an independent process, and is included in the term if the intended purpose of the process is achieved even when it cannot be clearly distinguished from other processes.
  • a numerical range indicated by using “to” indicates a range including the numerical values described before and after “to” as the minimum value and the maximum value, respectively.
  • the content of each component in the composition means the total amount of the plurality of substances present in the composition unless there is a specific notice when there are a plurality of substances corresponding to each component in the composition.
  • the term “layer” includes a configuration of a shape formed in part in addition to a configuration of a shape formed on the entire surface when observed as a plan view.
  • a first solar cell element of the present invention includes a light receiving surface and a semiconductor substrate having a back surface opposite to the light receiving surface, a light receiving surface electrode disposed on the light receiving surface of the semiconductor substrate, and a back surface of the semiconductor substrate.
  • a back electrode disposed on the semiconductor substrate; and a passivation layer disposed on the back surface of the semiconductor substrate and containing aluminum oxide.
  • a solar cell element having a passivation layer containing aluminum oxide on the back surface has excellent conversion efficiency and suppresses deterioration of solar cell characteristics over time.
  • the second solar cell element of the present invention has a light receiving surface and a back surface opposite to the light receiving surface, and a p-type diffusion region containing a p-type impurity and an n-type diffusion containing an n-type impurity on the back surface.
  • a semiconductor substrate having a region, a first metal electrode provided on the p-type diffusion region, a second metal electrode provided on the n-type diffusion region, and part or all of the back surface of the semiconductor substrate
  • a passivation layer provided in the region and containing aluminum oxide.
  • a solar cell element having a passivation layer containing an electrode and aluminum oxide on the back surface is excellent in conversion efficiency and suppresses deterioration of solar cell characteristics over time.
  • a third solar cell element of the present invention includes a semiconductor substrate having a light receiving surface and a back surface opposite to the light receiving surface, and a first impurity diffusion disposed on a part of the light receiving surface and having impurities diffused therein.
  • a back surface electrode disposed on the back surface, and a passivation layer disposed on at least one of the light receiving surface and the back surface and containing aluminum oxide.
  • a solar cell element having a passivation layer containing aluminum oxide has excellent conversion efficiency and suppresses deterioration of solar cell characteristics over time.
  • the passivation layer contains aluminum oxide, an excellent passivation effect is exhibited and the lifetime of carriers in the semiconductor substrate is extended, so that high efficiency can be achieved.
  • the fall of the solar cell characteristic for example, conversion efficiency
  • the persistence of the passivation effect by aluminum oxide can be suppressed by the persistence of the passivation effect by aluminum oxide.
  • the deterioration of the solar cell characteristics over time can be evaluated by the solar cell characteristics after being left for a predetermined time in a constant temperature and humidity chamber.
  • the passivation effect of a semiconductor substrate refers to an effective lifetime of minority carriers in a semiconductor substrate on which a passivation layer is formed by using a device such as Nippon Semi-Lab Co., Ltd., WT-2000PVN, etc. It can be evaluated by measuring by the method.
  • the effective lifetime ⁇ is expressed by the following equation (A) by the bulk lifetime ⁇ b inside the semiconductor substrate and the surface lifetime ⁇ s of the semiconductor substrate surface.
  • ⁇ s becomes long, resulting in a long effective lifetime ⁇ .
  • the bulk lifetime ⁇ b is increased and the effective lifetime ⁇ is increased. That is, by measuring the effective lifetime ⁇ , the interface characteristics between the passivation layer and the semiconductor substrate and the internal characteristics of the semiconductor substrate such as dangling bonds can be evaluated.
  • the first solar cell element includes a semiconductor substrate having a light receiving surface and a back surface opposite to the light receiving surface.
  • the semiconductor substrate include those obtained by doping (diffusing) p-type impurities or n-type impurities into silicon, germanium, or the like.
  • the semiconductor substrate may be a p-type semiconductor substrate or an n-type semiconductor substrate. Among these, from the viewpoint of the passivation effect, a semiconductor substrate in which the surface on which the passivation layer is formed (that is, the back surface) is a p-type layer is preferable.
  • the p-type layer on the semiconductor substrate is a p-type layer derived from the p-type semiconductor substrate
  • the p-type layer is formed on the n-type semiconductor substrate or the p-type semiconductor substrate as a p-type diffusion layer or a p + -type diffusion layer. It may be a thing.
  • the p-type layer and the n-type layer are preferably pn-junctioned on the semiconductor substrate. That is, when the semiconductor substrate is a p-type semiconductor substrate, an n-type layer is preferably formed on the light receiving surface or the back surface of the semiconductor substrate. When the semiconductor substrate is an n-type semiconductor substrate, it is preferable that a p-type layer is formed on the light receiving surface or the back surface of the semiconductor substrate.
  • the method for forming the p-type layer or the n-type layer on the semiconductor substrate is not particularly limited, and can be appropriately selected from commonly used methods.
  • the thickness of the semiconductor substrate is not particularly limited and can be appropriately selected according to the purpose.
  • the thickness of the semiconductor substrate can be 50 ⁇ m to 1000 ⁇ m, preferably 75 ⁇ m to 750 ⁇ m.
  • the shape and size of the semiconductor substrate are not limited, and for example, it is preferably a square having a side of 125 mm to 156 mm.
  • the first solar cell element has a light receiving surface electrode disposed on the light receiving surface and a back electrode disposed on the back surface opposite to the light receiving surface of the semiconductor substrate.
  • the light receiving surface electrode has a function of collecting current on the light receiving surface of the semiconductor substrate.
  • the back electrode has a function of outputting a current to the outside, for example.
  • the first solar cell element is not particularly limited in the material, shape and thickness of the light-receiving surface electrode.
  • Examples of the material of the light receiving surface electrode include silver, copper, and aluminum.
  • the thickness of the light-receiving surface electrode is preferably 0.1 ⁇ m to 50 ⁇ m from the viewpoint of conductivity and homogeneity.
  • the first solar cell element is not particularly limited in the material, shape and thickness of the back electrode.
  • the material for the back electrode include silver, copper, and aluminum.
  • the material of the back electrode is preferably aluminum from the viewpoint of forming the back electrode and diffusing aluminum atoms in the semiconductor substrate to form a p + -type diffusion layer.
  • the thickness of the back electrode is preferably 0.1 ⁇ m to 50 ⁇ m from the viewpoint of conductivity and substrate warpage.
  • the light-receiving surface electrode and the back surface electrode in the first solar cell element can be manufactured by a commonly used method.
  • an electrode forming paste such as a silver paste, an aluminum paste, or a copper paste is applied to a desired region of a semiconductor substrate, and heat treatment (firing) is performed as necessary to manufacture a light receiving surface electrode and a back electrode.
  • heat treatment firing
  • a passivation layer containing aluminum oxide is disposed on at least the back surface of the semiconductor substrate.
  • the passivation layer may be provided on a part or the whole of the back surface, and is preferably provided on at least a part other than the region where the back electrode is provided.
  • the passivation layer may be provided in at least a part of the region selected from the group consisting of the side surface and the light receiving surface of the semiconductor substrate in addition to the back surface.
  • the second solar cell element includes a semiconductor substrate having a light receiving surface and a back surface opposite to the light receiving surface, and having a p-type diffusion region and an n-type diffusion region on the back surface.
  • the semiconductor substrate include those obtained by doping (diffusing) p-type impurities or n-type impurities into silicon, germanium, or the like.
  • the semiconductor substrate may be a p-type semiconductor substrate or an n-type semiconductor substrate.
  • the surface on which the passivation layer is formed is preferably a semiconductor substrate having a p-type layer.
  • the p-type layer on the semiconductor substrate is a p-type layer derived from the p-type semiconductor substrate
  • the p-type layer is formed on the n-type semiconductor substrate or the p-type semiconductor substrate as a p-type diffusion layer or a p + -type diffusion layer. It may be a thing.
  • the thickness of the semiconductor substrate is not particularly limited and can be appropriately selected according to the purpose.
  • the thickness of the semiconductor substrate can be 50 ⁇ m to 1000 ⁇ m, preferably 75 ⁇ m to 750 ⁇ m.
  • the shape and size of the semiconductor substrate are not limited, and for example, it is preferably a square having a side of 125 mm to 156 mm.
  • the semiconductor substrate has a p-type diffusion region and an n-type diffusion region on the back surface.
  • the shape and size of the p-type diffusion region and the n-type diffusion region are not particularly limited and can be appropriately selected according to the purpose.
  • the p-type diffusion region and the n-type diffusion region are preferably arranged apart from each other.
  • the number and shape of the p-type diffusion region and the n-type diffusion region are not particularly limited as long as the effect and the shape of the present invention are achieved.
  • the p-type diffusion region and the n-type diffusion region each have at least a rectangular portion having a long side and a short side. Note that the short side and the long side of the rectangular portion may each be a straight line or may include a non-straight part.
  • the number of rectangular portions arranged in the p-type diffusion region and the n-type diffusion region on the back surface of the semiconductor substrate is not particularly limited and can be appropriately selected according to the purpose and the like. It is preferable that
  • the long sides of the plurality of rectangular portions of the p-type diffusion region are preferably arranged along the long sides of the plurality of rectangular portions of the n-type diffusion region. It is preferable that the plurality of rectangular portions and the plurality of rectangular portions included in the n-type diffusion region are alternately arranged.
  • the plurality of rectangular portions of the p-type diffusion region are connected.
  • a plurality of rectangular portions of the n-type diffusion region may be connected. For example, you may connect with the rectangular n-type diffusion area
  • FIG. 14B shows an example of the arrangement of the p + type diffusion layer (p type diffusion region) 14 and the n + type diffusion layer (n type diffusion region) 12 formed on the back surface of the semiconductor substrate.
  • the p-type diffusion region 14 is spaced apart from the n-type diffusion region 12.
  • the p + -type diffusion layer (p-type diffusion region) 14 has a plurality of rectangular portions each having a short side 14a and a long side 14b.
  • the rectangular portions of the plurality of p + -type diffusion layers (p-type diffusion regions) 14 are connected by a rectangular p + -type diffusion layer (p-type diffusion region) 14c disposed at one end in the direction of the long side 14b. ing.
  • the n + -type diffusion layer (n-type diffusion region) 12 also has a plurality of rectangular portions having short sides and long sides.
  • the rectangular portion of the plurality of n + -type diffusion layer (n-type diffusion region) 12 is coupled with each of the rectangular n + -type diffusion layer which is disposed at one end in the long side direction (n-type diffusion region) 12c Yes.
  • a rectangular portion 14 c that connects a plurality of rectangular portions of the p + -type diffusion layer (p-type diffusion region) 14 connects a plurality of rectangular portions of the n + -type diffusion layer (n-type diffusion region) 12.
  • the rectangular portion 12c is arranged on the opposite side when viewed in the long side direction.
  • the p + -type diffusion layer (p-type diffusion region) 14 and the n + -type diffusion layer (n-type diffusion region) 12 are connected to each other while the p + -type diffusion layer (p-type diffusion region) 14 is connected to each other.
  • a plurality of rectangular portions of (p-type diffusion region) 14 and a plurality of rectangular portions of n + -type diffusion layer (n-type diffusion region) 12 can be alternately arranged.
  • Such a back electrode structure is also referred to as “intersecting finger type”.
  • a back contact type solar cell element can be mentioned.
  • FIG. 14A is a schematic cross-sectional view taken along the line BB in FIG. 14B.
  • an n + -type diffusion layer 12 is formed on the light-receiving surface side of the n-type semiconductor substrate 11, and a p + -type diffusion layer (p-type diffusion region) 14 and an n + -type diffusion layer (n-type diffusion region) are formed on the back surface.
  • p-type diffusion region p-type diffusion region
  • n + -type diffusion layer n + -type diffusion region
  • the concentration of the p-type impurity contained in the p-type diffusion region provided on the back surface of the semiconductor substrate and the concentration of the n-type impurity contained in the n-type diffusion region are not particularly limited.
  • the concentration of the p-type impurity contained in the p-type diffusion region is preferably higher than the concentration of the p-type impurity contained in the semiconductor substrate.
  • the concentration of the p-type impurity contained in the p-type diffusion region is 10 18 atoms / cm 3 or more, and the concentration of the p-type impurity contained in the semiconductor substrate is 10 5 atoms / cm 3 or more and 10 17 atoms / cm 3. 3 or less, the concentration of the p-type impurity contained in the p-type diffusion region is 10 19 atoms / cm 3 or more and 10 22 atoms / cm 3 or less, and the concentration of the p-type impurities contained in the semiconductor substrate Is more preferably 10 10 atoms / cm 3 or more and 10 16 atoms / cm 3 or less.
  • the concentration of the n-type impurity contained in the n-type diffusion region may be higher than the concentration of the n-type impurity contained in the semiconductor substrate.
  • the concentration of the n-type impurity contained in the n-type diffusion region is 10 18 atoms / cm 3 or more
  • the concentration of the n-type impurity contained in the semiconductor substrate is 10 5 atoms / cm 3 or more and 10 17 atoms / cm 3.
  • the concentration of the n-type impurity contained in the n-type diffusion region is located 10 19 atoms / cm 3 or more 10 22 atoms / cm 3, the concentration of the n-type impurity contained in the semiconductor substrate More preferably, it is 10 10 atoms / cm 3 or more and 10 16 atoms / cm 3 or less.
  • the concentration of the p-type impurity contained in the p-type diffusion region is reduced in the semiconductor substrate in the second solar cell element from the viewpoint of conversion efficiency and longer carrier lifetime.
  • concentration of the n-type impurity contained in the semiconductor substrate is higher than the concentration of the p-type impurity contained, and when the semiconductor substrate is an n-type semiconductor substrate, the concentration of the n-type impurity contained in the n-type diffusion region is The p-type diffusion region has a plurality of rectangular portions each having a short side and a long side, and the p-type diffusion region has a plurality.
  • the long side direction of the rectangular portion is arranged along the long side direction of the plurality of rectangular portions of the n-type diffusion region, and the plurality of rectangular portions of the p-type diffusion region and the plurality of n-type diffusion regions have Alternating with the rectangular part of It is preferred that the.
  • the first metal electrode is provided in the p-type diffusion region on the back surface of the semiconductor substrate, and the second metal electrode is provided in the n-type diffusion region.
  • the material, shape, and thickness of the 1st metal electrode and 2nd metal electrode which are provided in a back surface examples include silver, copper, and aluminum.
  • the thickness of the electrode is preferably 0.1 ⁇ m to 50 ⁇ m from the viewpoint of conductivity and homogeneity.
  • the shape and size of the region where the first metal electrode is formed in the p-type diffusion region are not particularly limited.
  • the size of the region where the first metal electrode is formed is preferably 50% or more, more preferably 80% or more of the total area of the p-type diffusion region.
  • the shape of the region where the first metal electrode is formed is preferably the same as the shape of the p-type diffusion region.
  • the shape and size of the region where the second metal electrode is formed in the n-type diffusion region are not particularly limited.
  • the size of the region where the second metal electrode is formed is preferably 50% or more, more preferably 80% or more of the total area of the n-type diffusion region.
  • the shape of the region where the second metal electrode is formed is preferably the same as the shape of the n-type diffusion region.
  • the first metal electrode provided in the p-type diffusion region is an aluminum electrode from the viewpoint of forming an electrode and diffusing aluminum atoms in the semiconductor substrate to form a p + -type diffusion layer.
  • the thickness is preferably 0.1 ⁇ m to 50 ⁇ m.
  • the first metal electrode and the second metal electrode provided on the back surface can be manufactured by a commonly used method. For example, it can be manufactured by applying an electrode forming paste such as a silver paste, an aluminum paste, or a copper paste to a desired region of a semiconductor substrate, and performing a heat treatment (firing) as necessary.
  • the second solar cell element may further include an electrode for collecting current on the light receiving surface of the semiconductor substrate as necessary.
  • an electrode for collecting current on the light receiving surface of the semiconductor substrate as necessary.
  • the material, shape, and thickness of the electrodes that collect current on the light receiving surface include silver, copper, and aluminum, and the thickness of the electrode is preferably 0.1 ⁇ m to 50 ⁇ m.
  • the electrode provided on the light receiving surface in the second solar cell element may be connected to the first metal electrode or the second metal electrode on the back surface through a through-hole electrode penetrating the semiconductor substrate.
  • the electrode provided on the light receiving surface in the second solar cell element can be manufactured by a commonly used method. For example, it can be manufactured by applying an electrode forming paste such as a silver paste, an aluminum paste, or a copper paste to a desired region of a semiconductor substrate, and performing a heat treatment (firing) as necessary.
  • the second solar cell element has a passivation layer containing aluminum oxide in a part or all of the back surface of the semiconductor substrate.
  • the passivation layer is preferably provided in 50% or more of the region area on the back surface of the semiconductor substrate, and more preferably in 80% or more.
  • the passivation layer may be provided on part or all of the side surface of the semiconductor substrate in addition to the back surface of the semiconductor substrate, or may be provided on part or all of the light receiving surface.
  • the shape and size in the surface direction of the region where the passivation layer is formed on the back surface of the semiconductor substrate are not particularly limited and can be appropriately selected according to the purpose and the like.
  • the passivation layer may be formed on a part or all of the region other than the region where the first metal electrode and the second metal electrode are formed.
  • it is more preferably formed in the entire region other than the region where the first metal electrode and the second metal electrode are formed.
  • the passivation layer may be formed on a part or all of the region other than the region where the first metal electrode or the second metal electrode is in ohmic contact with the semiconductor substrate on the back surface of the semiconductor substrate.
  • the passivation layer is formed in part or all of the region other than the p-type diffusion region and the n-type diffusion region on the back surface of the semiconductor substrate.
  • the third solar cell element includes a semiconductor substrate having a light receiving surface and a back surface opposite to the light receiving surface.
  • the semiconductor substrate include those obtained by doping (diffusing) p-type impurities or n-type impurities into silicon, germanium, or the like.
  • the semiconductor substrate may be a p-type semiconductor substrate or an n-type semiconductor substrate.
  • the surface on which the passivation layer is formed is preferably a semiconductor substrate having a p-type layer.
  • the p-type layer on the semiconductor substrate is a p-type layer derived from the p-type semiconductor substrate
  • the p-type layer is formed on the n-type semiconductor substrate or the p-type semiconductor substrate as a p-type diffusion layer or a p + -type diffusion layer. It may be a thing.
  • the p-type layer and the n-type layer are pn-junctioned in the semiconductor substrate in the third solar cell element. That is, when the semiconductor substrate is a p-type semiconductor substrate, an n-type layer is preferably formed on the light-receiving surface or the back surface of the semiconductor substrate. When the semiconductor substrate is an n-type semiconductor substrate, it is preferable that a p-type layer is formed on the light receiving surface or the back surface of the semiconductor substrate.
  • the method for forming the p-type layer or the n-type layer on the semiconductor substrate is not particularly limited, and can be appropriately selected from commonly used methods.
  • the thickness of the semiconductor substrate in the third solar cell element is not particularly limited, and can be appropriately selected according to the purpose. For example, it can be 50 ⁇ m to 1000 ⁇ m, preferably 75 ⁇ m to 750 ⁇ m. Further, the shape and size of the semiconductor substrate is not limited, and for example, it is preferably a square having a side of 125 mm to 156 mm.
  • the solar cell element in the third solar cell element has a light receiving surface electrode disposed on the light receiving surface and a back electrode disposed on the back surface opposite to the light receiving surface in the semiconductor substrate.
  • the light receiving surface electrode is disposed on the first impurity diffusion layer having a higher impurity concentration on the light receiving surface.
  • the light receiving surface electrode has a function of collecting current on the light receiving surface of the semiconductor substrate.
  • the back electrode has a function of outputting a current to the outside, for example.
  • the material, shape and thickness of the light receiving surface electrode in the third solar cell element there is no particular limitation on the material, shape and thickness of the light receiving surface electrode in the third solar cell element.
  • the material of the light receiving surface electrode include silver, copper, and aluminum.
  • the thickness of the light-receiving surface electrode is preferably 0.1 ⁇ m to 50 ⁇ m from the viewpoint of conductivity and homogeneity.
  • the material for the back electrode include silver, copper, and aluminum.
  • the material of the back electrode is preferably aluminum from the viewpoint of forming the back electrode and forming the p + -type diffusion layer.
  • the thickness of the back electrode is preferably 0.1 ⁇ m to 50 ⁇ m from the viewpoint of conductivity and warpage of the substrate.
  • the light-receiving surface electrode and the back surface electrode in the third solar cell element can be manufactured by a commonly used method.
  • it can be manufactured by applying an electrode forming paste such as a silver paste, an aluminum paste, or a copper paste to a desired region of a semiconductor substrate, and performing a heat treatment (firing) as necessary.
  • the first impurity diffusion layer and the second impurity diffusion layer in the third solar cell element are an n-type diffusion layer or a p-type diffusion layer.
  • the semiconductor substrate in the third solar cell element is a p-type semiconductor
  • the light-receiving surface of the semiconductor substrate has a region of the first n-type diffusion layer and an n-type impurity concentration higher than that of the first n-type diffusion layer.
  • a region of the low second n-type diffusion layer is disposed. It is preferable to arrange the first n-type diffusion layer region directly under the light-receiving surface electrode and the second n-type diffusion layer region in the other light-receiving surface region.
  • the contact resistance with the electrode can be lowered, and a solar cell using this semiconductor substrate In the device, the series resistance can be lowered.
  • the second n-type diffusion layer having a low impurity concentration in addition to the region directly under the electrode, it is possible to effectively use short-wavelength sunlight, and it is generated by absorbing sunlight. The recombination rate of electrons and holes can be reduced. Such a structure is called a selective emitter structure.
  • the semiconductor substrate in the third solar cell element is an n-type semiconductor
  • the region of the first p-type diffusion layer on the light-receiving surface of the semiconductor substrate and the p-type impurity concentration is lower than that of the first p-type diffusion layer.
  • a region of the second p-type diffusion layer is disposed. It is preferable to arrange the first p-type diffusion layer region directly under the light-receiving surface electrode and the second p-type diffusion layer region in the other light-receiving surface region.
  • the third solar cell element having the selective emitter structure as described above can generate power with high conversion efficiency.
  • the sheet resistance of the first n-type diffusion layer or the first p-type diffusion layer is preferably 20 ⁇ / ⁇ to 60 ⁇ / ⁇ , more preferably 30 ⁇ / ⁇ to 55 ⁇ / ⁇ , and further 35 ⁇ / ⁇ to 50 ⁇ / ⁇ . preferable.
  • the sheet resistance of the second n-type diffusion layer or the second p-type diffusion layer is preferably 60 ⁇ / ⁇ to 150 ⁇ / ⁇ , more preferably 70 ⁇ / ⁇ to 130 ⁇ / ⁇ , and further 80 ⁇ / ⁇ to 120 ⁇ / ⁇ . preferable. Sheet resistance can be measured by a four-probe method.
  • a passivation layer containing aluminum oxide is disposed on at least one of the light receiving surface and the back surface of the semiconductor substrate.
  • the passivation layer may be provided on a part or the entire surface of at least one of the light receiving surface and the back surface, and is preferably provided in a region other than the back electrode on the back surface. Further, the passivation layer may be provided in at least a part of the side surface of the semiconductor substrate in addition to the light receiving surface and the back surface.
  • the passivation layer in the first to third solar cell elements of the present invention is a heat-treated product (baked product) of a composition for forming a passivation layer containing an organoaluminum compound, from the viewpoint of exhibiting a more excellent passivation effect.
  • a heat-treated product (baked product) of a composition for forming a passivation layer containing an organoaluminum compound represented by the following general formula (I) hereinafter also referred to as “specific organoaluminum compound”.
  • each R 1 independently represents an alkyl group having 1 to 8 carbon atoms.
  • n represents an integer of 0 to 3.
  • X 2 and X 3 each independently represent an oxygen atom or a methylene group.
  • R 2 , R 3 and R 4 each independently represents a hydrogen atom or an alkyl group having 1 to 8 carbon atoms.
  • the average thickness of the passivation layer formed on the semiconductor substrate is not particularly limited and can be appropriately selected depending on the purpose.
  • the average thickness of the passivation layer is preferably 5 nm to 50 ⁇ m, more preferably 10 nm to 30 ⁇ m, and still more preferably 15 nm to 20 ⁇ m from the viewpoint of the passivation effect.
  • the average thickness of the passivation layer was measured at three points using a stylus type step / surface shape measuring device (for example, Ambios), a spectroscopic ellipsometer, an interference type film thickness meter (for example, Filmetrics). It can be obtained as an arithmetic average value of thickness.
  • the aluminum oxide in the passivation layer preferably contains at least an aluminum oxide having an amorphous structure (hereinafter also referred to as “amorphous aluminum oxide”) from the viewpoint of conversion efficiency.
  • amorphous aluminum oxide an aluminum oxide having an amorphous structure
  • the formation amount of tetracoordinate aluminum oxide, which is considered necessary for expressing the passivation effect is increased, and the passivation effect is further improved. It is thought to do.
  • Whether the passivation layer contains amorphous aluminum oxide can be confirmed by analytical methods such as an X-ray absorption spectrum and X-ray diffraction.
  • the passivation layer contains amorphous aluminum oxide is calculated from the peaks of ⁇ , ⁇ , and ⁇ -alumina, which are crystallized aluminum oxides, when the passivation layer is analyzed by X-ray diffraction spectrum. It means that the crystallinity X is 99 or less.
  • the degree of crystallinity X (Ic) / (Ic + Ia) ⁇ 100, where Ic represents the crystalline scattering integral intensity derived from aluminum oxide, and Ia represents the amorphous scattering integral intensity derived from aluminum oxide.
  • the abundance ratio of amorphous aluminum oxide in the aluminum oxide contained in the passivation layer there is no particular limitation on the abundance ratio of amorphous aluminum oxide in the aluminum oxide contained in the passivation layer.
  • the proportion of amorphous aluminum oxide present in an aluminum oxide layer (passivation layer) having an average thickness of 20 nm provided on a semiconductor substrate is preferably 1% by mass to 100% by mass, and preferably 10% by mass to 100% by mass. %, More preferably 30% by mass to 100% by mass.
  • the abundance ratio of the amorphous aluminum oxide can be measured by an X-ray absorption spectrum, an X-ray diffraction analysis method or the like, and it is preferable that a crystallized aluminum oxide phase is not detected.
  • amorphous aluminum oxide when included as aluminum oxide, it is only necessary that amorphous aluminum oxide be included in the surface layer up to a depth of 100 nm from the surface of the semiconductor substrate. Whether the surface layer contains amorphous aluminum oxide can be examined using a transmission electron microscope (TEM) and a scanning transmission electron microscope (STEM).
  • TEM transmission electron microscope
  • STEM scanning transmission electron microscope
  • the content of aluminum oxide contained in the passivation layer is preferably 1% by mass to 100% by mass, more preferably 10% by mass to 99% by mass, and more preferably 20% by mass from the viewpoint of the passivation effect. More preferably, the content is in the range of% to 98% by mass.
  • the content of aluminum oxide contained in the passivation layer can be determined by using atomic absorption spectrometry, inductively coupled plasma emission spectroscopy, thermogravimetry, X-ray photoelectric spectroscopy, or the like. First, the ratio of inorganic substances is calculated from thermogravimetric analysis. Next, the proportion of the aluminum compound in the inorganic substance is calculated by atomic absorption spectrometry, inductively coupled plasma emission spectroscopy, or the like, and the proportion of aluminum oxide is further calculated by X-ray photoelectric spectroscopy.
  • the passivation layer contains aluminum oxide and may further contain a metal oxide (inorganic oxide) other than aluminum oxide in addition to aluminum oxide.
  • metal oxides (inorganic oxides) other than aluminum oxide include silicon oxide, titanium oxide, gallium oxide, zirconium oxide, boron oxide, indium oxide, phosphorus oxide, and zinc oxide.
  • the passivation layer contains a metal oxide other than aluminum oxide, the content is preferably 95% by mass or less, and more preferably 50% by mass or less.
  • the density of the passivation layer from the viewpoint of temporal stability of the passivation effect, preferably 1.0g / cm 3 ⁇ 8.0g / cm 3, more preferably 2.0g / cm 3 ⁇ 6.0g / cm 3 3.0 g / cm 3 to 5.0 g / cm 3 is more preferable.
  • the density of the passivation layer can be calculated from the area and thickness of the passivation layer and the mass of the passivation layer. Specifically, the density of the passivation layer is measured using a pressure floating method or a temperature floating method.
  • the passivation layer in the solar cell element of the present invention is preferably formed by heat-treating a composition for forming a passivation layer containing an organoaluminum compound (hereinafter also referred to as “the composition for forming a passivation layer according to the present invention”). .
  • a solar cell element having a passivation layer having a more excellent passivation effect and excellent in conversion efficiency can be produced by a simple method. Furthermore, by using the composition for forming a passivation layer, the passivation layer can be formed on the semiconductor substrate on which the electrode is formed so as to have a desired shape, which is superior to the productivity of the solar cell element.
  • the organoaluminum compound preferably contains at least one organoaluminum compound represented by the following general formula (I).
  • the composition for forming a passivation layer preferably contains at least one organoaluminum compound represented by the following general formula (I) and at least one liquid medium.
  • the composition for forming a passivation layer may further contain other components as necessary.
  • each R 1 independently represents an alkyl group having 1 to 8 carbon atoms.
  • n represents an integer of 0 to 3.
  • X 2 and X 3 each independently represent an oxygen atom or a methylene group.
  • R 2 , R 3 and R 4 each independently represents a hydrogen atom or an alkyl group having 1 to 8 carbon atoms.
  • a plurality of groups represented by the same symbol may be the same or different.
  • a passivation layer having an excellent passivation effect is obtained by applying a composition for forming a passivation layer containing a specific organoaluminum compound to a semiconductor substrate to form a composition layer having a desired shape and then heat-treating (baking) the composition layer. Can be formed into a desired shape.
  • This method is a simple and highly productive method that does not require a vapor deposition apparatus or the like. Furthermore, this method can form a passivation layer in a desired shape without requiring a complicated process such as mask processing.
  • the composition for forming a passivation layer containing a specific organoaluminum compound occurrence of problems such as gelation is suppressed, and the storage stability with time is excellent.
  • the composition for forming a passivation layer preferably contains at least one organoaluminum compound, and the organoaluminum compound contains at least one organoaluminum compound (specific organoaluminum compound) represented by the general formula (I). It is preferable to include.
  • the specific organoaluminum compound includes compounds called aluminum alkoxide, aluminum chelate and the like, and preferably has an aluminum chelate structure in addition to the aluminum alkoxide structure. Further, as described in Nippon Seramikkusu Kyokai Gakujitsu Ronbunshi, 97 (1989) 369-399, the organoaluminum compound becomes aluminum oxide (Al 2 O 3 ) by heat treatment (firing).
  • a passivation layer having an excellent passivation effect can be formed by using a composition for forming a passivation layer containing a specific organoaluminum compound as follows.
  • Aluminum oxide formed by heat-treating (firing) a passivation layer-forming composition containing a specific organoaluminum compound is likely to be in an amorphous state, and a four-coordinate aluminum oxide layer is generated near the interface with the semiconductor substrate and is large. It is thought that it can have a negative fixed charge.
  • Tetracoordinated aluminum oxide is considered to be a structure in which the center of silicon dioxide (SiO 2 ) is isomorphously substituted from silicon to aluminum, and is formed as a negative charge source at the interface between silicon dioxide and aluminum oxide like zeolite and clay. It is known that
  • the state of the formed aluminum oxide layer can be confirmed by measuring an X-ray diffraction spectrum (XRD, X-ray diffraction). For example, it can be confirmed that the XRD has an amorphous structure by not showing a specific reflection pattern.
  • the negative fixed charge of aluminum oxide can be evaluated by the CV method (Capacitance Voltage measurement).
  • the surface state density of the passivation layer formed from the composition for forming a passivation layer according to the present invention may be larger than that of an aluminum oxide layer formed by an ALD method or a CVD method.
  • the passivation layer formed from the composition for forming a passivation layer according to the present invention has a large electric field effect and a low minority carrier concentration, resulting in a long surface lifetime ⁇ s . Therefore, the surface state density is not a relative problem.
  • each R 1 independently represents an alkyl group having 1 to 8 carbon atoms, and is preferably an alkyl group having 1 to 4 carbon atoms.
  • the alkyl group represented by R 1 may be linear or branched, and is preferably unsubstituted.
  • alkyl group represented by R 1 in the general formula (I) examples include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, a sec-butyl group, a t-butyl group, and a hexyl group. Octyl group, 2-ethylhexyl group and the like.
  • the alkyl group represented by R 1 is preferably an unsubstituted alkyl group having 1 to 8 carbon atoms from the viewpoint of storage stability and a passivation effect, and is an unsubstituted alkyl group having 1 to 4 carbon atoms. More preferably.
  • n represents an integer of 0 to 3. From the viewpoint of storage stability, n is preferably an integer of 1 to 3, more preferably 1 or 3, and still more preferably 1.
  • X 2 and X 3 each independently represent an oxygen atom or a methylene group. From the viewpoint of storage stability, at least one of X 2 and X 3 is preferably an oxygen atom.
  • R 2 , R 3 and R 4 in the general formula (I) each independently represent a hydrogen atom or an alkyl group having 1 to 8 carbon atoms.
  • the alkyl group represented by R 2 , R 3 and R 4 may be linear or branched.
  • the alkyl group represented by R 2 , R 3 and R 4 may have a substituent or may be unsubstituted, and is preferably unsubstituted.
  • the alkyl group represented by R 2 , R 3 and R 4 in the general formula (I) is an alkyl group having 1 to 8 carbon atoms, and preferably an alkyl group having 1 to 4 carbon atoms.
  • Specific examples of the alkyl group represented by R 2 , R 3 and R 4 include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, a sec-butyl group, a t-butyl group, and a hexyl group.
  • R 2 and R 3 in the general formula (I) are each independently preferably a hydrogen atom or an unsubstituted alkyl group having 1 to 8 carbon atoms. Or it is more preferably an unsubstituted alkyl group having 1 to 4 carbon atoms.
  • R 4 in the general formula (I) is preferably a hydrogen atom or an unsubstituted alkyl group having 1 to 8 carbon atoms from the viewpoint of storage stability and a passivation effect, and is preferably a hydrogen atom or an unsubstituted alkyl group having 1 to 4 carbon atoms. It is more preferably a substituted alkyl group.
  • n 1 to 3
  • R 4 is independently a hydrogen atom or an alkyl group having 1 to 4 carbon atoms.
  • a compound is preferred.
  • the organoaluminum compound represented by the general formula (I) is a compound in which n is 0 and R 1 is independently an alkyl group having 1 to 4 carbon atoms from the viewpoint of storage stability and a passivation effect.
  • N is 1 to 3
  • R 1 is each independently an alkyl group having 1 to 4 carbon atoms
  • at least one of X 2 and X 3 is an oxygen atom
  • R 2 and R 3 are each independently It is preferably a hydrogen atom or an alkyl group having 1 to 4 carbon atoms
  • R 4 is independently at least one selected from the group consisting of compounds each independently being a hydrogen atom or an alkyl group having 1 to 4 carbon atoms. .
  • n is 0, R 1 is each independently an unsubstituted alkyl group having 1 to 4 carbon atoms, and n is 1 And R 1 is independently an unsubstituted alkyl group having 1 to 4 carbon atoms, at least one of X 2 and X 3 is an oxygen atom, and R 2 or R bonded to the oxygen atom When 3 is an alkyl group having 1 to 4 carbon atoms and X 2 or X 3 is a methylene group, R 2 or R 3 bonded to the methylene group is a hydrogen atom, and R 4 is a hydrogen atom. More preferably, it is at least one selected from the group consisting of:
  • Specific examples of the specific organoaluminum compound (aluminum trialkoxide) in which n is 0 in the general formula (I) include trimethoxyaluminum, triethoxyaluminum, triisopropoxyaluminum, trisec-butoxyaluminum, monosec-butoxy -Diisopropoxyaluminum, tri-t-butoxyaluminum, tri-n-butoxyaluminum and the like.
  • Specific examples of the specific organoaluminum compound in which n is 1 to 3 in the general formula (I) include aluminum ethyl acetoacetate diisopropylate (also referred to as “(ethylacetoaceto) aluminum isopropoxide”), aluminum Tris (ethyl acetoacetate), aluminum methyl acetoacetate diisopropylate, aluminum monoacetylacetonate bis (ethyl acetoacetate), aluminum tris (acetylacetonate), aluminum ethyl acetoacetate monoisopropylate monooleate it can.
  • aluminum ethyl acetoacetate diisopropylate also referred to as “(ethylacetoaceto) aluminum isopropoxide”
  • aluminum Tris ethyl acetoacetate
  • aluminum methyl acetoacetate diisopropylate aluminum monoacetylacetonate bis (ethyl acetoacetate)
  • aluminum tris
  • a prepared product or a commercially available product may be used as the specific organoaluminum compound in which n is 1 to 3 in the general formula (I).
  • Commercially available products include, for example, trade names of Kawaken Fine Chemical Co., Ltd., ALCH, ALCH-TR, aluminum chelate M, aluminum chelate D, aluminum chelate A (W) and the like.
  • the specific organoaluminum compound in which n is 1 to 3 in the general formula (I) can be prepared by mixing the aluminum trialkoxide and a compound having a specific structure having two carbonyl groups.
  • a compound having a specific structure having two carbonyl groups When an aluminum trialkoxide and a compound having a specific structure having two carbonyl groups are mixed, at least a part of the alkoxide group of the aluminum trialkoxide is substituted with the compound having the specific structure to form an aluminum chelate structure.
  • a liquid medium may be present, or heat treatment, addition of a catalyst, and the like may be performed.
  • the stability of the specific organoaluminum compound to hydrolysis and polymerization reaction is improved, and the storage stability of the composition for forming a passivation layer is further improved.
  • the compound having a specific structure having two carbonyl groups is at least one selected from the group consisting of ⁇ -diketone compounds, ⁇ -ketoester compounds, and malonic acid diesters from the viewpoint of reactivity and storage stability. preferable.
  • ⁇ -diketone compounds include acetylacetone, 3-methyl-2,4-pentanedione, 2,3-pentanedione, 3-ethyl-2,4-pentanedione, and 3-butyl-2,4-pentane.
  • Examples include dione, 2,2,6,6-tetramethyl-3,5-heptanedione, 2,6-dimethyl-3,5-heptanedione, 6-methyl-2,4-heptanedione, and the like.
  • ⁇ -ketoester compounds include methyl acetoacetate, ethyl acetoacetate, propyl acetoacetate, isobutyl acetoacetate, butyl acetoacetate, t-butyl acetoacetate, pentyl acetoacetate, isopentyl acetoacetate, hexyl acetoacetate, acetoacetic acid n-octyl, heptyl acetoacetate, 3-pentyl acetoacetate, ethyl 2-acetylheptanoate, ethyl 2-butylacetoacetate, ethyl 4,4-dimethyl-3-oxovalerate, ethyl 4-methyl-3-oxovalerate Ethyl 2-ethylacetoacetate, ethyl hexylacetoacetate, methyl 4-methyl-3-oxovalerate, isopropyl acetoacetate, e
  • malonic acid diester examples include dimethyl malonate, diethyl malonate, dipropyl malonate, diisopropyl malonate, dibutyl malonate, di-t-butyl malonate, dihexyl malonate, t-butylethyl malonate, methyl malonate
  • examples include diethyl, diethyl ethylmalonate, diethyl isopropylmalonate, diethyl butylmalonate, diethyl sec-butylmalonate, diethyl isobutylmalonate, diethyl 1-methylbutylmalonate, and the like.
  • the number of aluminum chelate structures is not particularly limited as long as it is 1 to 3. Among these, 1 or 3 is preferable from the viewpoint of storage stability, and 1 is more preferable from the viewpoint of solubility.
  • the number of aluminum chelate structures can be controlled, for example, by appropriately adjusting the mixing ratio of the aluminum trialkoxide and a compound having a specific structure having two carbonyl groups. Moreover, you may select suitably the compound which has a desired structure from a commercially available aluminum chelate compound.
  • organoaluminum compounds represented by the general formula (I) specifically from the viewpoint of the passivation effect and the compatibility with the liquid medium added as necessary, specifically, aluminum ethyl acetoacetate diisopropylate, triisopropoxy It is preferable to use at least one selected from the group consisting of aluminum, trisec-butoxyaluminum, aluminum tris (ethyl acetoacetate) and aluminum methyl acetoacetate diisopropylate. Aluminum ethylacetoacetate diisopropylate, trisec-butoxy It is more preferable to use at least one selected from the group consisting of aluminum and aluminum tris (ethyl acetoacetate).
  • an aluminum chelate structure in a specific organoaluminum compound can be confirmed by a commonly used analysis method. Specifically, it can be confirmed using an infrared spectrum, a nuclear magnetic resonance spectrum, a melting point and the like.
  • the specific organoaluminum compound may be liquid or solid and is not particularly limited. From the viewpoint of the passivation effect and storage stability, it is preferable to use a specific organoaluminum compound having good stability at room temperature (25 ° C.) and good solubility or dispersibility in a liquid medium. . By using such a specific organoaluminum compound, the homogeneity of the formed passivation layer is further improved, and a desired passivation effect tends to be stably obtained.
  • the content of the organoaluminum compound contained in the composition for forming a passivation layer can be appropriately selected as necessary.
  • the content of the organoaluminum compound can be 0.5% by mass to 80% by mass in the composition for forming a passivation layer from the viewpoint of storage stability and a passivation effect, and is 1% by mass to 70% by mass. It is preferably 1% by mass to 60% by mass, more preferably 3% by mass to 60% by mass, particularly preferably 5% by mass to 50% by mass, and more preferably 10% by mass to It is very preferable that it is 30 mass%.
  • the content of the organoaluminum compound may be 0.1% by mass to 50% by mass in the composition for forming a passivation layer.
  • the composition for forming a passivation layer preferably contains a liquid medium.
  • the viscosity can be easily adjusted, the impartability can be further improved, and a more uniform passivation layer can be formed.
  • the liquid medium is not particularly limited and can be appropriately selected as necessary.
  • liquid medium examples include acetone, methyl ethyl ketone, methyl-n-propyl ketone, methyl isopropyl ketone, methyl-n-butyl ketone, methyl isobutyl ketone, methyl-n-pentyl ketone, methyl-n-hexyl ketone, diethyl ketone, Ketone solvents such as dipropyl ketone, diisobutyl ketone, trimethylnonanone, cyclohexanone, cyclopentanone, methylcyclohexanone, 2,4-pentanedione, acetonylacetone; diethyl ether, methyl ethyl ether, methyl-n-propyl ether, diisopropyl Ether, tetrahydrofuran, methyltetrahydrofuran, dioxane, dimethyldioxane, ethylene glycol dimethyl ether
  • the liquid medium preferably contains at least one selected from the group consisting of a terpene solvent, an ester solvent, an ether solvent, and an alcohol solvent from the viewpoints of impartability to a semiconductor substrate and pattern formation properties. It is more preferable to include at least one selected from the group consisting of a solvent and an alcohol solvent, and it is even more preferable to include at least one selected from the group consisting of a terpene solvent.
  • the content of the liquid medium is determined in consideration of the imparting property, the pattern forming property, or the storage stability.
  • the content of the liquid medium is preferably 5% by mass to 98% by mass with respect to the total mass of the composition for forming a passivation layer, from the viewpoint of impartability of the composition for forming a passivation layer and pattern forming properties. More preferably, the content is 10% by mass to 95% by mass.
  • the composition for forming a passivation layer further contains at least one resin.
  • the shape stability of the composition layer formed by applying the composition for forming the passivation layer on the semiconductor substrate is further improved, and the passivation layer is formed in a desired region in the region where the composition layer is formed. It can be selectively formed by shape.
  • the type of resin is not particularly limited. Among these, when the composition for forming a passivation layer is applied on a semiconductor substrate, a resin capable of adjusting the viscosity within a range in which a good pattern can be formed is preferable.
  • the resin include polyvinyl alcohol, polyacrylamide, polyacrylamide derivatives, polyvinyl amide, polyvinyl amide derivatives, polyvinyl pyrrolidone, polyethylene oxide, polyethylene oxide derivatives, polysulfonic acid, acrylamide alkyl sulfonic acid, cellulose, cellulose derivatives (carboxymethyl cellulose, Hydroxyethyl cellulose, cellulose ethers such as ethyl cellulose), gelatin, gelatin derivatives, starch, starch derivatives, sodium alginate, sodium alginate derivatives, xanthan, xanthan derivatives, guar gum, guar gum derivatives, scleroglucan, scleroglucan derivatives, tragacanth,
  • (meth) acrylic acid means at least one of acrylic acid and methacrylic acid
  • (meth) acrylate means at least one of acrylate (acrylic acid ester) and the corresponding methacrylate (methacrylic acid ester).
  • the molecular weight of the resin is not particularly limited, and is preferably adjusted appropriately in view of a desired viscosity as the passivation layer forming composition.
  • the weight average molecular weight of the resin is preferably 1,000 to 10,000,000, and more preferably 3,000 to 5,000,000, from the viewpoints of storage stability and pattern formation.
  • the weight average molecular weight of resin is calculated
  • the content of the resin in the composition for forming a passivation layer can be appropriately selected as necessary.
  • the resin content is preferably 0.1% by mass to 30% by mass in the total mass of the composition for forming a passivation layer.
  • the content is more preferably 1% by mass to 25% by mass, and further preferably 1.5% by mass to 20% by mass.
  • the content is particularly preferably 1.5 to 10% by mass.
  • the content ratio of the organoaluminum compound and the resin in the composition for forming a passivation layer can be appropriately selected as necessary.
  • the mass ratio of the resin to the organoaluminum compound is preferably 0.001 to 1000, and preferably 0.01 to 100. Is more preferable, and 0.1 to 1 is still more preferable.
  • composition for forming a passivation layer may further contain an organic compound represented by the general formula (II).
  • the composition for forming a passivation layer can further improve the passivation effect by containing the organic compound represented by the general formula (II), and can suppress black residue after heat treatment (firing). it can.
  • organic compound represented by general formula (II) isobornyl cyclohexanol is mentioned, for example.
  • Telsolve MTPH (Nippon Terpene Chemical Co., Ltd., trade name) is commercially available as isobornylcyclohexanol. Isobornyl cyclohexanol has a high boiling point of 308 ° C. to 318 ° C. When it is removed from the composition layer, it does not need to be degreased by heat treatment (firing) like a resin, but is vaporized by heating. Can be eliminated. For this reason, most of the liquid medium and isobornylcyclohexanol contained in the composition for forming a passivation layer can be removed in the drying step after being applied on the semiconductor substrate, and heat treatment (firing) Later black residue can be suppressed.
  • the content of the organic compound represented by the general formula (II) contained in the composition for forming a passivation layer is preferably 30% by mass to 99.9% by mass, and 40% by mass to 95% by mass. Is more preferable, and 60 to 90% by mass is even more preferable.
  • the composition for forming a passivation layer contains the organic compound represented by the general formula (II), it should contain substantially no resin (for example, 3% by mass or less, preferably 2.5% by mass or less). , More preferably 2% by mass or less). By containing substantially no resin, black residue after heat treatment (firing) can be further suppressed.
  • the composition for forming a passivation layer may contain an acidic compound or a basic compound.
  • the content of the acidic compound or the basic compound is 1% by mass or less in the composition for forming a passivation layer, respectively. It is preferable that the content is 0.1% by mass or less.
  • acidic compounds include Bronsted acid and Lewis acid. Specific examples include inorganic acids such as hydrochloric acid and nitric acid, and organic acids such as acetic acid.
  • Examples of basic compounds include Bronsted bases and Lewis bases. Specific examples include inorganic bases such as alkali metal hydroxides and alkaline earth metal hydroxides, and organic bases such as trialkylamine and pyridine.
  • the composition for forming a passivation layer may contain various additives such as a thickener, a wetting agent, a surfactant, an inorganic powder, a resin containing a silicon atom, and a thixotropic agent, as necessary, as other components. Good.
  • the inorganic powder examples include silica (silicon oxide), clay, silicon carbide, silicon nitride, montmorillonite, bentonite, carbon black and the like. Among these, it is preferable to use a filler containing silica as a component.
  • clay refers to a layered clay mineral, and specific examples include kaolinite, imogolite, montmorillonite, smectite, sericite, illite, talc, stevensite, and zeolite.
  • the surfactant examples include nonionic surfactants, cationic surfactants, anionic surfactants and the like. Among these, nonionic surfactants or cationic surfactants are preferred because impurities such as heavy metals are not brought into the semiconductor device. Furthermore, examples of nonionic surfactants include silicon surfactants, fluorine surfactants, and hydrocarbon surfactants. By containing the surfactant, the uniformity (thickness and composition) of the printed matter of the composition for forming a passivation layer tends to be improved.
  • Resins containing silicon atoms include lysine-modified silicones at both ends, alternating copolymers of polyamide and silicone, side-chain alkyl-modified silicone, side-chain polyether-modified silicone, quantity-end alkyl-modified silicone, silicone-modified pullulan, silicone-modified acrylic, etc. Can be illustrated.
  • the uniformity (thickness and composition) of the printed matter of the composition for forming a passivation layer tends to be improved.
  • thixotropic agents examples include polyether compounds, fatty acid amides, fumed silica, hydrogenated castor oil, urea urethane amide, polyvinyl pyrrolidone, oil-based gelling agents and the like.
  • thixotropic agent By containing the thixotropic agent, the fine line formability of the printed matter of the composition for forming a passivation layer (suppression of expansion of the contact area on the printed surface of the printed matter at the time of printing and drying) tends to be improved.
  • polyether compounds include polyethylene glycol, polypropylene glycol, and poly (ethylene-propylene) glycol copolymers.
  • the viscosity of the composition for forming a passivation layer is not particularly limited, and can be appropriately selected depending on a method for applying the composition to a semiconductor substrate.
  • the viscosity of the composition for forming a passivation layer can be 0.01 Pa ⁇ s to 10,000 Pa ⁇ s.
  • the viscosity of the composition for forming a passivation layer is preferably 0.1 Pa ⁇ s to 1000 Pa ⁇ s.
  • the viscosity is measured using a rotary shear viscometer at 25 ° C. and a shear rate of 1.0 s ⁇ 1 .
  • the shear viscosity of the composition for forming a passivation layer is not particularly limited, and it is preferable that the composition for forming a passivation layer has thixotropy.
  • the passivation layer forming composition comprising a resin from the viewpoint of pattern formability is calculated by dividing the shear viscosity eta 1 at a shear rate of 1.0 s -1 at shear viscosity eta 2 at a shear rate of 10s -1
  • the thixo ratio ( ⁇ 1 / ⁇ 2 ) is preferably 1.05 to 100, more preferably 1.1 to 50.
  • the shear viscosity is measured at a temperature of 25 ° C. using a rotary shear viscometer equipped with a cone plate (diameter 50 mm, cone angle 1 °).
  • the method for producing the composition for forming a passivation layer can be produced by mixing an organoaluminum compound and a liquid medium or the like contained as necessary by a commonly used method.
  • the resin may be dissolved in a liquid medium and then mixed with the organoaluminum compound.
  • the organoaluminum compound represented by the general formula (I) may be prepared by mixing aluminum alkoxide and a compound capable of forming a chelate with aluminum. At that time, a liquid medium may be appropriately used or heat treatment may be performed.
  • the composition for forming a passivation layer may be produced by mixing the organoaluminum compound represented by the general formula (I) thus prepared and a resin or a solution containing a resin.
  • the components contained in the composition for forming a passivation layer and the content of each component are determined by thermal analysis such as differential thermal-thermogravimetric simultaneous measurement (TG / DTA), nuclear magnetic resonance (NMR), infrared spectroscopy ( It can be confirmed by spectral analysis such as IR), chromatographic analysis such as high performance liquid chromatography (HPLC), gel permeation chromatography (GPC) and the like.
  • thermal analysis such as differential thermal-thermogravimetric simultaneous measurement (TG / DTA), nuclear magnetic resonance (NMR), infrared spectroscopy ( It can be confirmed by spectral analysis such as IR), chromatographic analysis such as high performance liquid chromatography (HPLC), gel permeation chromatography (GPC) and the like.
  • the first to third methods for producing solar cell elements include a step of applying a composition for forming a passivation layer containing at least an organoaluminum compound to a semiconductor substrate to form a composition layer, and heat-treating the composition layer (Baking) to form a passivation layer containing aluminum oxide.
  • a solar cell element having a passivation layer having an excellent passivation effect and excellent in conversion efficiency can be produced by a simple method. Furthermore, even on the semiconductor substrate on which the electrode is formed, the passivation layer can be formed so as to have a desired shape, and the productivity of the solar cell element is excellent.
  • the first solar cell element manufacturing method includes a step of forming a light receiving surface electrode on a light receiving surface of a semiconductor substrate having a light receiving surface and a back surface opposite to the light receiving surface, and a back electrode on the back surface of the semiconductor substrate. Forming a passivation layer-forming composition containing an organoaluminum compound on the back surface of the semiconductor substrate, and heat-treating (baking) the composition layer. Forming a passivation layer containing aluminum oxide.
  • the method for manufacturing a solar cell element may further include other steps as necessary.
  • a solar cell element having a passivation layer having an excellent passivation effect and excellent in conversion efficiency can be produced by a simple method. Furthermore, even on the semiconductor substrate on which the electrode is formed, the passivation layer can be formed so as to have a desired shape, and the productivity of the solar cell element is excellent.
  • the p-type layer and the n-type layer are preferably pn-junctioned.
  • the semiconductor substrate can be manufactured by a commonly used method. Commercial products may also be used.
  • the method for forming the light-receiving surface electrode and the back electrode is not particularly limited, and can be appropriately selected from commonly used methods.
  • the light-receiving surface electrode and the back electrode can be formed by applying an electrode forming paste such as a silver paste or an aluminum paste to a desired region of the semiconductor substrate and performing a heat treatment (firing) as necessary.
  • the order in particular of the process of forming a light-receiving surface electrode and the process of forming a back surface electrode is not restrict
  • the composition for forming a passivation layer described above may be applied by a known application method or the like. And a method of applying to a part or all of the back surface of the semiconductor substrate.
  • Specific examples include various printing methods such as dipping method and screen printing method, spin coating method, brush coating, spray method, doctor blade method, roll coater method, and ink jet method. Among these, from the viewpoint of pattern formability, various printing methods, ink jet methods and the like are preferable, and screen printing methods are more preferable.
  • the amount of the passivation layer forming composition applied to the semiconductor substrate can be appropriately selected according to the purpose.
  • the thickness of the passivation layer to be formed can be appropriately adjusted so as to have a desired thickness.
  • a passivation layer is formed on the back surface of the semiconductor substrate by heat-treating (baking) the composition layer formed by the composition for forming a passivation layer to form a heat-treated product (baked product) derived from the composition layer. can do.
  • the heat treatment (firing) conditions of the composition layer are not particularly limited as long as the organoaluminum compound contained in the composition layer can be converted into aluminum oxide (Al 2 O 3 ) that is the heat treatment product (firing product).
  • the heat treatment (firing) conditions that can form a layer containing amorphous Al 2 O 3 having no specific crystal structure are preferable.
  • the passivation layer is composed of a layer containing amorphous Al 2 O 3 , the passivation layer can effectively have a negative charge, and a more excellent passivation effect can be obtained.
  • the heat treatment (firing) temperature is preferably 400 ° C. or higher, more preferably 400 ° C.
  • the heat treatment (firing) time can be appropriately selected according to the heat treatment (firing) temperature and the like. For example, it can be 0.1 to 10 hours, and preferably 0.1 to 5 hours.
  • the step of applying the passivation layer forming composition on the back surface of the semiconductor base substrate to form the composition layer and the step of forming the passivation layer by heat-treating (firing) the formed composition layer include the light-receiving surface electrode and It may be performed before the back surface electrode is formed, or may be performed after the light receiving surface electrode and the back surface electrode are formed.
  • FIG. 1 is a cross-sectional view schematically showing an example of a method for producing a first solar cell element having a passivation layer.
  • this process diagram does not limit the present invention.
  • an n + -type diffusion layer 2 is formed in the vicinity of the surface, and an antireflection film 3 is formed on the outermost surface.
  • the antireflection film 3 include a silicon nitride film and a titanium oxide film.
  • a surface protective film such as silicon oxide may further exist between the antireflection film 3 and the p-type semiconductor substrate 1.
  • the passivation layer according to the present invention may be used as a surface protective film.
  • a material for forming the back electrode 5 such as an aluminum electrode paste is applied to a partial region of the back surface, followed by heat treatment to form the back electrode 5 and a p-type semiconductor substrate. 1, aluminum atoms are diffused into p + type diffusion layer 4.
  • the electrode-forming paste is applied to the light-receiving surface side, and then heat-treated to form the light-receiving surface electrode 7.
  • those containing glass powder having a fire-through property as an electrode forming paste, reaches through the antireflective film 3, as shown in FIG. 1 (c), on the n + -type diffusion layer 2, the light-receiving surface
  • the electrode 7 can be formed to obtain an ohmic contact.
  • FIG. 3 is a plan view schematically showing an example of the back electrode arrangement on the semiconductor substrate on which the back electrode 5 is formed.
  • a plurality of rectangular back electrodes 5 are arranged on the p-type layer 1 so as to be separated from each other.
  • FIG. 4 is a plan view schematically showing another example of the back electrode arrangement in the semiconductor substrate on which the back electrode 5 is formed.
  • two rectangular back electrodes 5 are provided on the p-type layer 1 so as to be spaced apart from each other, and are arranged so that the long sides thereof are along.
  • the arrangement of the back electrode may be the embodiment shown in FIG. 3 or the embodiment shown in FIG.
  • FIG. 5 is a plan view schematically showing an example of the arrangement of the light receiving surface electrodes on the semiconductor substrate on which the light receiving surface electrodes 7 are formed.
  • a light receiving surface finger electrode 8 and a light receiving surface bus bar electrode 9 may be formed.
  • L2 indicates the length of one side of the semiconductor substrate
  • L8 indicates the width of the light-receiving surface bus bar electrode
  • L9 indicates the width of the light-receiving surface finger electrode 8.
  • FIG. 1 shows (b) and (c) as separate steps, but the steps (b) and (c) may be combined into one step.
  • a material for forming the back electrode 5 such as an aluminum electrode paste
  • An electrode forming paste may be applied to the surface side, and heat treatment may be performed at this stage.
  • electrodes on the back surface and the light receiving surface are formed by batch heat treatment, and the process is simplified.
  • the surface of the semiconductor substrate 1 is preferably washed with an alkaline aqueous solution before applying the passivation layer forming composition.
  • an alkaline aqueous solution By washing with an alkaline aqueous solution, organic substances, particles, and the like present on the surface of the semiconductor substrate can be removed, and the passivation effect is further improved.
  • a method for cleaning with an alkaline aqueous solution generally known RCA cleaning and the like can be exemplified.
  • the semiconductor substrate can be washed by immersing the semiconductor substrate in a mixed solution of ammonia water and hydrogen peroxide water and treating at 60 ° C. to 80 ° C. to remove organic substances and particles.
  • the washing time is preferably 10 seconds to 10 minutes, and more preferably 30 seconds to 5 minutes.
  • a composition for forming a passivation layer is formed on the p-type layer on the back surface other than the region where the back electrode 5 is formed to form a composition layer.
  • the application method include a method of applying a passivation layer forming composition on a semiconductor substrate using a known application method or the like. Specific examples include various printing methods such as dipping method, screen printing, spin coating method, brush coating, spray method, doctor blade method, roll coater method, and ink jet method. Among these, from the viewpoint of pattern formability, various printing methods, ink jet methods and the like are preferable, and screen printing methods are more preferable.
  • the amount of the passivation layer-forming composition applied to the semiconductor substrate can be appropriately selected according to the purpose. For example, the application amount of the composition for forming a passivation layer can be appropriately adjusted so that the thickness of the formed passivation layer is the above-described preferable thickness.
  • the method further includes a step of drying the composition layer before the step of forming the passivation layer by the subsequent heat treatment (firing). Also good.
  • a passivation layer having a more uniform passivation effect can be formed.
  • the step of drying the composition layer is not particularly limited as long as at least a part of the liquid medium that may be contained in the passivation layer forming composition can be removed.
  • the drying treatment can be, for example, a heat treatment at 30 ° C. to 250 ° C. for 1 minute to 60 minutes, and is preferably a heat treatment at 40 ° C. to 220 ° C. for 3 minutes to 40 minutes.
  • the drying treatment may be performed under normal pressure or under reduced pressure.
  • the composition layer formed on the p-type layer is heat-treated (fired) to form the passivation layer 6.
  • the heat treatment (firing) conditions of the composition layer are not particularly limited as long as the organoaluminum compound contained in the composition layer can be converted into aluminum oxide (Al 2 O 3 ) that is the heat treatment product (firing product).
  • the heat treatment (firing) conditions that can form an amorphous Al 2 O 3 layer having no specific crystal structure are preferable.
  • the passivation layer is composed of an amorphous Al 2 O 3 layer, the passivation layer can effectively have a negative charge, and a more excellent passivation effect can be obtained.
  • the heat treatment (firing) temperature is preferably 400 ° C.
  • the heat treatment (firing) time can be appropriately selected according to the heat treatment (firing) temperature and the like.
  • the heat treatment (firing) time can be 0.1 to 10 hours, preferably 0.1 to 5 hours.
  • FIG. 6 is an example of a plan view of the back surface of the semiconductor substrate in which the back electrode 5 and the passivation layer 6 are formed on the p-type layer 1.
  • a plurality of rectangular back electrodes 5 are arranged apart from each other, and a passivation layer 6 is formed in a region other than the back electrodes 5.
  • L1 indicates the length of one side of the region where the passivation layer 6 is formed
  • L2 indicates the length of one side of the semiconductor substrate.
  • L3 and L4 each indicate the length of one side of the rectangular back electrode 5.
  • FIG. 7 is another example of a plan view of the back surface of the semiconductor substrate in which the back electrode 5 and the passivation layer 6 are formed on the p-type layer 1.
  • two rectangular back electrodes 5 are provided so as to be spaced apart from each other and are arranged so that the long sides thereof are along, and a passivation layer 6 is formed in a region other than the back electrode 5.
  • L1 indicates the length of one side of the region where the passivation layer 6 is formed
  • L2 indicates the length of one side of the semiconductor substrate.
  • L5 indicates the length of the short side of the rectangular back electrode 5.
  • L3 and L4, which are the lengths of one side of the rectangular back electrode 5, are preferably 10 ⁇ m to 156 mm, respectively.
  • L5, which is the length of the short side of the rectangular back electrode 5, is preferably 50 ⁇ m to 10 mm.
  • L2 which is the length of one side of the semiconductor substrate is preferably 125 mm to 156 mm.
  • L1 which is the length of one side of the region where the passivation layer is formed is preferably 100 ⁇ m to 156 mm.
  • L8 which is the width of the light receiving surface bus bar electrode 9 is preferably 500 ⁇ m to 3 mm
  • L9 which is the width of the light receiving surface finger electrode 8 is preferably 10 ⁇ m to 400 ⁇ m.
  • the back electrode formed from aluminum or the like can have a point contact structure (for example, the electrode arrangement shown in FIG. 3), and the warp of the substrate Etc. can be reduced. Furthermore, by using the composition for forming a passivation layer, a passivation layer can be formed with excellent productivity on the p-type layer other than the region where the electrode is formed.
  • 1D shows a method of forming a passivation layer only on the back surface portion.
  • the passivation layer forming composition is also applied to the side surface, and this is heat treated (baked).
  • a passivation layer may be further formed on the side surface (edge) of the semiconductor substrate 1 (not shown).
  • the composition for forming a passivation layer is particularly effective when used in a place where there are many crystal defects such as side surfaces.
  • an electrode such as aluminum may be formed in a desired region by vapor deposition or the like.
  • FIG. 2 is a cross-sectional view schematically showing another process example of the method for manufacturing the first solar cell element having the passivation layer.
  • FIG. 2 shows the heat treatment of the aluminum electrode paste after forming the p + type diffusion layer using the aluminum electrode paste or the p type diffusion layer forming composition capable of forming the p + type diffusion layer by thermal diffusion treatment.
  • the process drawing including the process of removing the heat-treated product of the product or the p + -type diffusion layer forming composition will be described as a cross-sectional view.
  • the p-type diffusion layer forming composition include a composition containing an acceptor element-containing substance and a glass component.
  • an n + -type diffusion layer 2 is formed in the vicinity of the surface of the p-type semiconductor substrate 1, and an antireflection film 3 is formed on the surface.
  • the antireflection film 3 include a silicon nitride film and a titanium oxide film.
  • the p + -type diffusion layer 4 is formed by applying a p + -type diffusion layer forming composition to a partial region of the back surface and then performing heat treatment.
  • a heat treatment product 8 of a composition for forming a p + type diffusion layer is formed on the p + type diffusion layer 4.
  • an aluminum electrode paste may be used instead of the p-type diffusion layer forming composition.
  • an aluminum electrode 8 is formed on the p + type diffusion layer 4.
  • the heat-treated product 8 or the aluminum electrode 8 of the p-type diffusion layer forming composition formed on the p + -type diffusion layer 4 is removed by a technique such as etching.
  • the electrode forming paste is selectively applied to the light receiving surface (front surface) and a partial region of the back surface, and then heat-treated, so that the light receiving surface electrode 7
  • the back electrode 5 is formed on the back surface.
  • the electrode forming paste for forming the back electrode 5 is not limited to the aluminum electrode paste, but may be a silver electrode paste or the like. An electrode forming paste capable of forming a lower resistance electrode can also be used. As a result, the power generation efficiency can be further increased.
  • the composition for passivation layer formation is provided on the p-type layer of the back surface other than the area
  • the application can be performed by an application method such as screen printing.
  • the passivation layer 6 is formed by heat-treating (sintering) the composition layer formed on the p-type layer.
  • FIG. 2E shows a method of forming a passivation layer only on the back surface portion, but in addition to the back surface side of the p-type semiconductor substrate 1, a passivation layer forming material is also applied to the side surface and dried.
  • a passivation layer may be further formed on the side surface (edge) of the p-type semiconductor substrate 1 (not shown). Thereby, the solar cell element which was further excellent in power generation efficiency can be manufactured.
  • the composition for forming a passivation layer is particularly effective when used in a place where there are many crystal defects such as side surfaces.
  • FIG. 2 illustrates an embodiment in which the passivation layer is formed after the electrode is formed, but an electrode such as aluminum may be formed in a desired region by vapor deposition or the like after the passivation layer is formed.
  • a solar cell element In the first method for manufacturing a solar cell element described above, a case where a p-type semiconductor substrate having an n + -type diffusion layer formed on the light-receiving surface has been described. However, a p + -type diffusion layer is formed on the light-receiving surface. A solar cell element can be manufactured in the same manner when the n-type semiconductor substrate is used. In this case, an n + type diffusion layer is formed on the back side.
  • the second method for manufacturing a solar cell element has a light receiving surface and a back surface opposite to the light receiving surface, and a p-type diffusion region containing p-type impurities and an n-type diffusion containing n-type impurities on the back surface.
  • the method for manufacturing a solar cell element may further include other steps as necessary.
  • a semiconductor substrate having a p-type diffusion region and an n-type diffusion region on the back surface can be manufactured by a commonly used method. For example, it can be produced according to the method described in Japanese Patent No. 3522940.
  • a method of forming metal electrodes on the p-type diffusion region and the n-type diffusion region for example, a paste for forming an electrode such as a silver paste or an aluminum paste is applied to a desired region of a semiconductor substrate. It can be formed by heat treatment (firing).
  • the step of forming the metal electrode on the p-type diffusion region and the n-type diffusion region may be performed before the step of forming the passivation layer, or may be performed after the step of forming the passivation layer. Good.
  • a method of applying the above-described composition for forming a passivation layer to a part or all of the back surface of the semiconductor substrate using a known application method or the like can be given.
  • Specific examples include various printing methods such as dipping method and screen printing method, spin coating method, brush coating, spray method, doctor blade method, roll coater method, and ink jet method. Among these, from the viewpoint of pattern formability, various printing methods, ink jet methods and the like are preferable, and screen printing methods are more preferable.
  • the application amount of the composition for forming a semiconductor substrate passivation layer can be appropriately selected according to the purpose.
  • the thickness of the passivation layer to be formed can be appropriately adjusted so as to have a desired thickness.
  • a passivation layer can be formed on a semiconductor substrate by heat-treating (baking) the composition layer formed by the composition for forming a passivation layer to form a heat-treated product (baked product) derived from the composition layer. it can.
  • the heat treatment (firing) conditions of the composition layer are not particularly limited as long as the organoaluminum compound contained in the composition layer can be converted into aluminum oxide (Al 2 O 3 ) that is the heat treatment product (firing product). Among them, the heat treatment (firing) conditions that can form a layer containing amorphous Al 2 O 3 having no specific crystal structure are preferable.
  • the passivation layer When the passivation layer is composed of a layer containing amorphous Al 2 O 3 , the passivation layer can effectively have a negative charge, and a more excellent passivation effect can be obtained.
  • the heat treatment (firing) temperature is preferably 400 ° C. or higher, more preferably 400 ° C. to 900 ° C., and still more preferably 450 ° C. to 800 ° C.
  • the heat treatment (firing) time can be appropriately selected according to the heat treatment (firing) temperature and the like. For example, it can be 0.1 to 10 hours, and preferably 0.1 to 5 hours.
  • FIG. 10 is a cross-sectional view schematically showing an example of a method for manufacturing a solar cell element having a passivation layer according to this embodiment.
  • this process diagram does not limit the present invention.
  • an n + type diffusion layer 12 is formed on the light receiving surface side of the n type semiconductor substrate 11, and p + type diffusion layers (p type diffusion regions) 14 and n + are formed on the back surface.
  • a type diffusion layer (n-type diffusion region) 12 is formed, and an antireflection film 13 is formed on the outermost surface on the light receiving surface side.
  • the p + -type diffusion layer 14 can be formed by, for example, applying a p-type diffusion layer forming composition or an aluminum electrode paste to a desired region and then performing a heat treatment.
  • the n + -type diffusion layer 12 can be formed by, for example, applying a composition for forming an n-type diffusion layer capable of forming an n + -type diffusion layer by thermal diffusion treatment to a desired region and then performing a heat treatment.
  • a composition for forming an n-type diffusion layer include a composition containing a donor element-containing material and a glass component.
  • the antireflection film 13 include a silicon nitride film and a titanium oxide film.
  • a surface protective film such as silicon oxide may further exist between the antireflection film 13 and the p-type semiconductor substrate 1.
  • the passivation layer according to the present invention may be used as the surface protective film.
  • a first metal electrode 15 and a second metal electrode 17 are formed as back electrodes on the p + type diffusion layer 14 and the n + type diffusion layer 12 on the back surface, respectively.
  • the back electrode can be formed by heat treatment after applying a commonly used electrode forming paste such as a silver electrode paste, an aluminum electrode paste, or a copper electrode paste.
  • the first metal electrode 15 may be heat-treated after applying a material for forming an electrode such as an aluminum electrode paste to form the first metal electrode 15 and the p + -type diffusion layer 14. Good.
  • the surface of the semiconductor substrate 11 is preferably washed with an alkaline aqueous solution before applying the passivation layer forming composition.
  • an alkaline aqueous solution By washing with an alkaline aqueous solution, organic substances, particles, and the like present on the surface of the semiconductor substrate can be removed, and the passivation effect is further improved.
  • As a method for cleaning with an alkaline aqueous solution generally known RCA cleaning and the like can be exemplified. For example, by immersing the semiconductor substrate in a mixed solution of ammonia water and hydrogen peroxide solution and treating at 60 ° C. to 80 ° C., organic substances and particles can be removed and washed.
  • the washing time is preferably 10 seconds to 10 minutes, and more preferably 30 seconds to 5 minutes.
  • the composition for forming a passivation layer is provided on the back surface of the semiconductor substrate other than the region where the first metal electrode 15 and the second metal electrode 17 are formed.
  • a composition layer is formed.
  • the application include a method of applying a passivation layer forming composition on a semiconductor substrate using a known application method or the like.
  • Specific examples include various printing methods such as dipping method and screen printing method, spin coating method, brush coating, spray method, doctor blade method, roll coater method, and ink jet method. Among these, from the viewpoint of pattern formability, various printing methods, ink jet methods and the like are preferable, and screen printing methods are more preferable.
  • the amount of the passivation layer-forming composition applied to the semiconductor substrate can be appropriately selected according to the purpose.
  • the application amount of the composition for forming a passivation layer can be appropriately adjusted so that the thickness of the formed passivation layer is the above-described preferable thickness.
  • the method further includes a step of drying the composition layer before the step of forming the passivation layer by the subsequent heat treatment (firing). Also good.
  • a passivation layer having a more uniform passivation effect can be formed.
  • the step of drying the composition layer is not particularly limited as long as at least a part of the liquid medium that may be contained in the passivation layer forming composition can be removed.
  • the drying treatment can be, for example, a heat treatment at 30 ° C. to 250 ° C. for 1 minute to 60 minutes, and is preferably a heat treatment at 40 ° C. to 220 ° C. for 3 minutes to 40 minutes.
  • the drying treatment may be performed under normal pressure or under reduced pressure.
  • the composition layer formed on the back surface of the semiconductor substrate is heat-treated (fired) to form the passivation layer 16.
  • the heat treatment (firing) conditions of the composition layer are not particularly limited as long as the organoaluminum compound contained in the composition layer can be converted into aluminum oxide (Al 2 O 3 ) that is the heat treatment product (firing product).
  • the heat treatment (firing) conditions that can form an amorphous Al 2 O 3 layer having no specific crystal structure are preferable.
  • the passivation layer is composed of an amorphous Al 2 O 3 layer, the passivation layer can effectively have a negative charge, and a more excellent passivation effect can be obtained.
  • the heat treatment (firing) temperature is preferably 400 ° C.
  • the heat treatment (firing) time can be appropriately selected according to the heat treatment (firing) temperature and the like. For example, it can be 0.1 to 10 hours, and preferably 0.2 to 5 hours.
  • the back electrode type solar cell element as shown in FIG. 10 is excellent in power generation efficiency because there is no electrode on the light receiving surface side. Furthermore, the solar cell element which is more excellent in power generation efficiency can be provided by forming a passivation layer in the back surface using the composition for forming a passivation layer.
  • FIG. 10C shows a method of forming a passivation layer only on the back surface portion, but in addition to the back surface of the semiconductor substrate 11, a passivation layer forming composition is applied to the side surface of the semiconductor substrate, and this is subjected to heat treatment.
  • a passivation layer may be further formed on the side surface (edge) of the semiconductor substrate 11 by (baking) (not shown). Thereby, the solar cell element excellent in power generation efficiency can be manufactured. The effect is particularly great when the passivation layer is provided in a place with many crystal defects such as side surfaces.
  • the 2nd solar cell element may also have the passivation layer 16 also in the light-receiving surface side like FIG.
  • FIG. 10 illustrates a mode in which the passivation layer is formed after the electrode is formed.
  • an electrode such as aluminum may be further formed in a desired region by vapor deposition or the like.
  • FIG. 12 is a plan view schematically showing an example of the back electrode pattern of the second solar cell element having a passivation layer.
  • FIG. 12 is a plan view when the second solar cell element is viewed from the back surface side. As described above, the back electrodes 20 and 21 are formed, and a passivation layer (not shown) is provided on a part or the entire surface other than where the back electrodes 20 and 21 are formed.
  • 10 (a) to 10 (c), FIG. 11 and FIG. 13 are cross-sectional views when the solar cell element in FIG. 12 is cut along line AA.
  • FIG. 10 shows an example in which an n-type semiconductor substrate is used as the semiconductor substrate, a solar cell element having excellent conversion efficiency can be manufactured according to the above even when a p-type semiconductor substrate is used.
  • FIG. 10 illustrates the case where an n-type semiconductor substrate having an n + -type diffusion layer formed on the light-receiving surface is used. However, an n-type semiconductor substrate having a p + -type diffusion layer formed on the light-receiving surface is described. Similarly, when used, a solar cell element can be produced. In this case, an n + type diffusion layer is formed on the back surface.
  • the second solar cell element may be a via-hole type back contact solar cell element whose schematic cross-sectional view is shown in FIG.
  • the above-described composition for forming a passivation layer can be used to form the passivation layer 16 on the light receiving surface or the back surface of the via-hole type back contact solar cell element as shown in FIG.
  • a method for manufacturing the via-hole type back contact solar cell element will be described.
  • the via-hole type back contact solar cell element As shown in a schematic cross-sectional view in FIG. 13, there is a through hole that connects the light receiving surface side and the back surface side.
  • the through hole is formed, for example, by irradiating an n-type semiconductor substrate with laser light.
  • the diameter of the opening of the through hole is about 50 ⁇ m to 150 ⁇ m, and the density of the opening of the through hole on the substrate surface is about 100 / cm 2 .
  • a p-type diffusion layer forming composition is applied to a desired region on the back surface, and p-type impurities are diffused to form p.
  • a + type diffusion layer 14 is formed.
  • a composition for forming an n-type diffusion layer is applied to the light receiving surface, and n-type impurities are diffused to form the n + -type diffusion layer 12.
  • a first metal electrode 15 and a second metal electrode 17 are formed on the formed p + -type diffusion layer 14 and n + -type diffusion layer 12, respectively.
  • a passivation layer 16 is formed in a region where the back electrode is not formed. In the back electrode type solar cell element as shown in FIG. 13, since there is no electrode on the light receiving surface side, the power generation efficiency is excellent. Furthermore, since the passivation layer is formed in the region where the back electrode is not formed, the conversion efficiency is further improved.
  • the passivation layer 16 provided on the back surface is provided with a composition for forming a passivation layer in a region where the first metal electrode 15 and the second metal electrode 17 that are back electrodes are not provided, and is heat-treated (fired). Can be formed. Further, the passivation layer 16 may be formed not only on the back surface of the semiconductor substrate 11 but also on the side surface and the wall surface of the through hole (not shown).
  • the third method for manufacturing a solar cell element includes a step of forming a region of a first impurity diffusion layer on a part of the light receiving surface of a semiconductor substrate having a light receiving surface and a back surface opposite to the light receiving surface; Forming a second impurity diffusion layer region having an impurity concentration lower than that of the first impurity diffusion layer on the light receiving surface; forming a light receiving surface electrode on the first impurity diffusion layer; A step of forming a back electrode on the back surface, a step of forming a composition layer by applying a composition for forming a passivation layer containing an organoaluminum compound on at least one of the light receiving surface and the back surface; And heat-treating the composition layer to form a passivation layer containing aluminum oxide.
  • the manufacturing method of the solar cell element may further include other steps as necessary.
  • the location where the passivation layer is formed is not particularly limited, but from the viewpoint of the degree of the passivation effect, the passivation layer is preferably present in the region where the p + -type diffusion layer is present or in the vicinity thereof.
  • the p-type layer and the n-type layer have a pn junction in the semiconductor substrate having the light-receiving surface and the back surface opposite to the light-receiving surface.
  • the semiconductor substrate can be manufactured by a commonly used method. Commercial products may also be used.
  • the method for forming the light-receiving surface electrode and the back electrode is not particularly limited, and can be appropriately selected from commonly used methods.
  • the light-receiving surface electrode and the back electrode can be formed by applying an electrode forming paste such as a silver paste or an aluminum paste to a desired region of the semiconductor substrate and performing a heat treatment (firing) as necessary.
  • the order in particular of the process of forming a light-receiving surface electrode and the process of forming a back surface electrode is not restrict
  • a method of applying the above-described composition for forming a passivation layer to a part or all of at least one of the light receiving surface and the back surface of the semiconductor substrate using a known application method or the like can be given.
  • Specific examples include various printing methods such as dipping method and screen printing method, spin coating method, brush coating, spray method, doctor blade method, roll coater method, and ink jet method. Among these, from the viewpoint of pattern formability, various printing methods, ink jet methods and the like are preferable, and screen printing methods are more preferable.
  • the amount of the passivation layer forming composition applied to the semiconductor substrate can be appropriately selected according to the purpose.
  • the application amount of the composition for forming a passivation layer can be appropriately adjusted so that the thickness of the passivation layer to be formed has a desired thickness.
  • a passivation layer is formed on at least one of the light-receiving surface and the back surface of the semiconductor substrate by heat-treating (baking) the composition layer formed from the passivation layer-forming composition to form a heat-treated product (baked product). can do.
  • the heat treatment (firing) conditions of the composition layer are not particularly limited as long as the organoaluminum compound contained in the composition layer can be converted into aluminum oxide (Al 2 O 3 ) that is the heat treatment product (firing product).
  • the heat treatment (firing) conditions be such that a passivation layer containing amorphous Al 2 O 3 having no specific crystal structure can be formed.
  • the heat treatment (firing) temperature is preferably 400 ° C. or higher, more preferably 400 ° C.
  • the heat treatment (firing) time can be appropriately selected according to the heat treatment (firing) temperature and the like.
  • the heat treatment (firing) time can be 0.1 to 10 hours, preferably 0.1 to 5 hours.
  • the step of performing may be performed before the light-receiving surface electrode and the back electrode are formed, or may be performed after the light-receiving surface electrode and the back electrode are formed.
  • FIG.15 and FIG.16 shows process drawing which shows typically an example of the manufacturing method of the 3rd solar cell element which has a passivation layer as sectional drawing.
  • this process diagram does not limit the present invention.
  • a p-type semiconductor substrate is used as the semiconductor substrate.
  • organic substances, particles, and the like present on the surface of the semiconductor substrate can be removed, and the passivation effect is further improved.
  • As a method for cleaning with an alkaline aqueous solution generally known RCA cleaning and the like can be exemplified. For example, by immersing the semiconductor substrate in a mixed solution of ammonia water and hydrogen peroxide water and treating at 60 ° C. to 80 ° C., organic substances and particles can be removed and washed.
  • the washing time is preferably 10 seconds to 10 minutes, and more preferably 30 seconds to 5 minutes.
  • the p-type semiconductor substrate 110 shown in FIG. 15A forms a texture structure (pyramid shape, not shown) on the light receiving surface (surface) by alkali etching or the like, and suppresses reflection of sunlight from the light receiving surface.
  • the n-type diffusion layer forming composition 111 is applied to a part of the light receiving surface, and is thermally diffused as shown in FIG. Layer 113 is formed.
  • a diffusion liquid containing phosphorus or antimony can be used as the n-type diffusion layer forming composition 111.
  • the thermal diffusion temperature is preferably 800 ° C. to 1000 ° C.
  • the n-type diffusion layer forming composition for example, the one described in JP 2012-084830 A may be used.
  • a PSG (phosphosilicate glass) layer 114 is then formed using phosphorus oxychloride or the like, and then a second n-type diffusion layer 115 is formed as shown in FIG. Form. Thereafter, the PSG layer 114 and the heat-treated product (baked product) 112 of the composition for forming an n-type diffusion layer are removed by dipping in an etching solution such as hydrofluoric acid (FIG. 15F).
  • an etching solution such as hydrofluoric acid
  • a p-type diffusion layer forming composition 116 is applied to the back surface of the semiconductor substrate.
  • the p-type diffusion layer forming composition may be applied to a part of the back surface or the entire surface of the semiconductor substrate.
  • the p-type diffusion layer forming composition can be a composition containing boron or the like.
  • the p-type diffusion layer forming composition for example, those described in JP2011-005312A can be used.
  • the p + -type diffusion layer 117 is formed by thermal diffusion.
  • the temperature for thermal diffusion is preferably 800 ° C. to 1050 ° C.
  • the heat-treated product (baked product) 116 ′ of the p-type diffusion layer forming composition is removed by dipping in an etching solution such as hydrofluoric acid (FIG. 15 (f)). .
  • an antireflection film 118 is formed on the light receiving surface.
  • the antireflection film 118 include a silicon nitride film and a titanium oxide film.
  • a surface protective film such as silicon oxide may further exist between the antireflection film 118 and the p-type semiconductor substrate 110.
  • the passivation layer according to the present invention may be used as a surface protective film.
  • a passivation layer 119 containing aluminum oxide as a main component is formed in a partial region of the back surface.
  • a method for forming the passivation layer 119 for example, using a known application method, a composition for forming a passivation layer is formed on a semiconductor substrate to form a composition layer, and the composition layer is subjected to heat treatment (firing).
  • heat treatment firing
  • various printing methods such as dipping method, screen printing, spin coating method, brush coating, spray method, doctor blade method, roll coater method, ink jet method, etc. Can be mentioned.
  • the amount of the passivation layer-forming composition applied to the semiconductor substrate can be appropriately selected according to the purpose.
  • the application amount of the composition for forming a passivation layer can be appropriately adjusted so that the thickness of the formed passivation layer is the above-described preferable thickness.
  • the heat treatment (firing) conditions of the passivation layer forming composition layer are not particularly limited as long as the organoaluminum compound contained in the composition layer can be converted into aluminum oxide (Al 2 O 3 ), which is the heat treated product (firing product). Not. Among them, the heat treatment (firing) conditions that can form an amorphous Al 2 O 3 layer having no specific crystal structure are preferable. When the passivation layer is composed of an amorphous Al 2 O 3 layer, the passivation layer can effectively have a negative charge, and a more excellent passivation effect can be obtained.
  • the heat treatment (firing) temperature is preferably 400 ° C. or higher, more preferably 400 ° C.
  • the heat treatment (firing) time can be appropriately selected according to the heat treatment (firing) temperature and the like.
  • the heat treatment (firing) time can be 0.1 to 10 hours, and preferably 0.2 to 5 hours.
  • an electrode forming paste is applied to the light receiving surface and the back surface side, and then heat treatment is performed to form the light receiving surface electrode 120 and the back electrode 121 as shown in FIG. 15 (m). .
  • the light-receiving surface electrode penetrates the antireflection film 115 and is received on the n-type diffusion layer 113 as shown in FIG.
  • the surface electrode 120 can be formed to obtain an ohmic contact.
  • a third solar cell element can be obtained.
  • the back electrode formed from aluminum or the like can have a point contact structure (for example, electrode arrangement shown in FIG. 17), The warp of the substrate can be reduced. Furthermore, by using the composition for forming a passivation layer, a passivation layer can be formed with excellent productivity on the p-type layer other than the region where the electrode is formed.
  • FIG. 16 shows an example using an n-type semiconductor substrate, which can be implemented by replacing the p-type and the n-type in FIG.
  • the p-type semiconductor substrate 110 is the n-type semiconductor substrate 130
  • the n-type diffusion layer forming composition 111 is the p-type diffusion layer forming composition 131
  • the n-type diffusion layer forming composition is heat-treated.
  • the (baked product) 112 is used as a heat-treated product (baked product) 132 of the p-type diffusion layer forming composition
  • the first n-type diffusion layer 113 is used as the first p-type diffusion layer 133
  • the second n-type diffusion layer is used.
  • the p-type diffusion layer forming composition 116 for the n-type diffusion layer forming composition 136, and a heat-treated product (baked product) 116 ′ of the p-type diffusion layer forming composition Is replaced with a heat-treated product (baked product) 136 ′ of the composition for forming an n-type diffusion layer, and p + -type diffusion layer 117 is replaced with an n + -type diffusion layer 137, respectively.
  • the PSG (phosphor silicate glass) layer 114 in FIG. 15 becomes the BSG (boron silicate glass) layer 134 in FIG.
  • FIG. 17 is a plan view schematically showing an example of the arrangement of the back electrode 121 in the semiconductor substrate on which the back electrode 121 is formed.
  • a plurality of rectangular back electrodes 121 are arranged on the p-type semiconductor substrate 110 so as to be separated from each other.
  • FIG. 18 is a plan view schematically showing another example of the back electrode arrangement in the semiconductor substrate on which the back electrode 121 is formed.
  • two rectangular back electrodes 121 are arranged on the p-type semiconductor substrate 110 so that their long sides are parallel to each other.
  • the arrangement of the back electrode 121 in the present invention may be the embodiment shown in FIG. 17 or the embodiment shown in FIG.
  • FIG. 19 is a plan view schematically showing an example of the arrangement of the light receiving surface electrodes on the semiconductor substrate on which the light receiving surface electrode 120 is formed.
  • a light receiving surface bus bar electrode 50 and a light receiving surface finger electrode 51 may be formed.
  • L2 indicates the length of one side of the semiconductor substrate
  • L8 indicates the width of the light receiving surface bus bar electrode 50
  • L9 indicates the width of the light receiving surface finger electrode 51.
  • the width L8 of the light receiving surface bus bar electrode 50 is preferably 500 ⁇ m to 3 mm
  • the width L9 of the light receiving surface finger electrode 51 is preferably 10 ⁇ m to 400 ⁇ m.
  • FIG. 20 is an example of a plan view of the back surface of the semiconductor substrate in which the back electrode 121 and the passivation layer 119 are formed on the p-type semiconductor substrate 110.
  • a plurality of rectangular back electrodes 121 are arranged apart from each other, and a passivation layer 119 is formed in a region other than the back electrodes 121.
  • L1 indicates the length of one side of the region where the passivation layer 119 is formed
  • L2 indicates the length of one side of the p-type semiconductor substrate 110.
  • L3 and L4 each indicate the length of one side of the rectangular back electrode 121.
  • L3 and L4 are each preferably 10 ⁇ m to 156 mm.
  • FIG. 21 is another example of a plan view of the back surface of the semiconductor substrate in which the back electrode 121 and the passivation layer 119 are formed on the p-type semiconductor substrate 110.
  • two rectangular back surface electrodes 121 are arranged so that their long sides are parallel to each other, and a passivation layer 119 is formed in a region other than the back surface electrode 121.
  • L1 indicates the length of one side of the region where the passivation layer 119 is formed
  • L2 indicates the length of one side of the p-type semiconductor substrate 10.
  • L5 indicates the length of the short side of the rectangular back electrode 121.
  • L5 is preferably 50 ⁇ m to 10 mm.
  • L2 which is the length of one side of the p-type semiconductor substrate 110 is preferably 125 mm to 156 mm.
  • L1 which is the length of one side of the region where the passivation layer 119 is formed is preferably 100 ⁇ m to 156 mm.
  • the solar cell module includes at least one of the solar cell elements, and is configured by arranging a wiring material on the electrode of the solar cell element. If necessary, the solar cell may be constituted by connecting a plurality of solar cell elements via a wiring material and further sealing with a sealing material.
  • the wiring material and the sealing material are not particularly limited, and can be appropriately selected from those usually used in the industry. There is no restriction
  • composition 1A for forming a passivation layer An organoaluminum compound solution was prepared by mixing 2.00 g of tri-sec-butoxyaluminum and 2.01 g of terpineol (product name: Terpineol-LW, Nippon Terpene Chemical Co., Ltd.). Separately from this, 5.00 g of ethyl cellulose (Nihon Kasei Co., Ltd., Etcelle STD200) and 95.02 g of terpineol were mixed and stirred at 150 ° C. for 1 hour to prepare an ethyl cellulose solution.
  • terpineol product name: Terpineol-LW, Nippon Terpene Chemical Co., Ltd.
  • Passivation layer forming composition 1A was prepared as a colorless and transparent solution by mixing 2.16 g of the obtained organoaluminum compound solution and 3.00 g of ethylcellulose solution.
  • the content of the ethyl cellulose in the passivation layer forming composition 1A was 2.9%, and the content of the organoaluminum compound was 20.9%.
  • Table 1 shows the content of each component. In the description of the composition in Table 1, “-” indicates that it was not added.
  • a single crystal p-type silicon substrate (SUMCO, 50 mm square, thickness: 625 ⁇ m) having a mirror-shaped surface was used.
  • the silicon substrate was pre-treated by immersing and cleaning at 70 ° C. for 5 minutes using an RCA cleaning solution (Kanto Chemical Co., Ltd., Frontier Cleaner-A01). After that, on the silicon substrate pretreated with the passivation layer forming composition 1A obtained above, it was applied to the entire mirror-shaped side surface using a screen printing method so that the thickness after drying was 5.0 ⁇ m. And dried at 150 ° C. for 3 minutes. Next, after heat treatment (baking) at 550 ° C. for 1 hour, the substrate was allowed to cool at room temperature (25 ° C.) to prepare an evaluation substrate.
  • the thickness of the prepared passivation layer was measured at three points using a stylus step meter (AmBios, XP-2) under the conditions of a speed of 0.1 mm / s and a needle load of 0.5 mg, and the arithmetic average value thereof
  • the average thickness was determined as follows.
  • the evaluation results are shown in Table 1.
  • the density of the passivation layer was calculated based on the difference in mass of the semiconductor substrate before application and after heat treatment (firing), and the area and thickness of the passivation layer.
  • the evaluation results are shown in Table 1. In the description of evaluation in Table 1, “-” indicates that it has not been evaluated.
  • the presence or absence of crystallized aluminum oxide was confirmed by X-ray diffraction analysis for the passivation layer of the substrate for evaluation. As a result, no crystallized aluminum oxide was detected, and it was found that all aluminum oxide was amorphous aluminum oxide. It was.
  • the measurement conditions in the X-ray diffraction analysis method are as follows. The X-ray diffraction pattern of the silicon substrate on which the passivation layer was formed was measured using an X-ray diffractometer (Rigaku Corporation, LAD-2X).
  • the X-ray source was Cu-K ⁇ , the output was 40 kV, the current was 20 mA, the incident slit was 1 °, the scattering slit was 1 °, the light receiving slit was 0.3 mm, and the scanning speed was 2 ° min ⁇ 1 .
  • the silicon peak was observed, and no peak derived from crystallized aluminum oxide was observed.
  • the effective lifetime ( ⁇ s) immediately after production (after 1 hour) was measured at room temperature (25 ° C.) using a lifetime measurement device (Nippon Semi-Lab Co., Ltd., WT-2000PVN) It was measured by the reflected microwave photoconductive decay method.
  • the effective lifetime immediately after production of the region to which the composition for forming a passivation layer of the obtained evaluation substrate was applied was 220 ⁇ s.
  • the stability over time was evaluated as follows. The results are shown in Table 1. The stability over time was evaluated by placing an evaluation substrate in a constant temperature and humidity layer at 50 ° C. and 80% RH, and measuring the effective lifetime in the same manner as described above after storage for 1 month. If the effective lifetime after storage is long, it can be said that the stability over time is excellent. The evaluation results are shown in Table 1.
  • a 156 mm square p-type silicon substrate (Advantech Co., Ltd., n-type diffusion layer sheet resistance: 60 ⁇ / ⁇ ) having an n-type diffusion layer formed on both sides using phosphorous oxychloride and an SiNx film formed on one side (light-receiving side) , Double-sided texture treated, SiNx film thickness: 80 nm) was used as the semiconductor substrate.
  • Screen-printing was performed using the composition 1A for forming a passivation layer obtained above so that the composition layer had a pattern as shown in FIG. 6 on the back surface of the semiconductor substrate.
  • the screen mask plate for forming the back electrode having the square opening 60 and the non-opening 61 of 8 mm ⁇ 8 mm shown in FIG. 8 is used to form a passivation layer forming composition 1A in a region other than the region where the back electrode is to be formed so that the thickness after drying is 5 ⁇ m.
  • heat treatment was performed at 550 ° C. for 1 hour to form a passivation layer, and then allowed to cool to room temperature (25 ° C.).
  • the power generation characteristics short circuit current density, open voltage, fill factor, conversion efficiency evaluated.
  • the results are shown in Table 1.
  • the evaluation was performed with a mask so that the light receiving area was 125 mm ⁇ 125 mm.
  • the power generation characteristics were measured according to JIS-C-8913 (fiscal 2005) and JIS-C-8914 (fiscal 2005).
  • the produced solar cell element was put in a constant temperature and humidity layer at 50 ° C. and 80% RH and stored for one month, and then the power generation characteristics of the solar cell element after storage were evaluated.
  • the results are shown in Table 1.
  • the change rate of the conversion efficiency after storage was 97.7%, and the conversion efficiency was reduced by 2.3%.
  • the evaluation results are shown in Table 1.
  • Example 2A Trisec-butoxyaluminum (4.79 g), ethyl acetoacetate (2.56 g) and terpineol (4.76 g) were mixed and stirred at 25 ° C. for 1 hour to obtain an organoaluminum compound solution. Separately, 12.02 g of ethyl cellulose and 88.13 g of terpineol were mixed and stirred at 150 ° C. for 1 hour to prepare an ethyl cellulose solution. Next, 2.93 g of an organoaluminum compound solution and 2.82 g of an ethyl cellulose solution were mixed to prepare a passivation layer forming composition 2A as a colorless transparent solution. The content of ethyl cellulose in the passivation layer forming composition 2A was 5.9%, and the content of the organoaluminum compound was 20.1%.
  • a passivation layer was formed on a pretreated silicon substrate and evaluated in the same manner as in Example 1A, except that the passivation layer forming composition 2A prepared above was used.
  • the effective lifetime was 204 ⁇ s.
  • a solar cell element was prepared and evaluated in the same manner as in Example 1A except that the passivation layer forming composition 2A was used instead of the passivation layer forming composition 1A.
  • the evaluation results are shown in Table 1.
  • Example 3A Trisec-butoxyaluminum (4.96 g), diethylmalonic acid (3.23 g) and terpineol (5.02 g) were mixed and stirred at 25 ° C. for 1 hour to obtain an organoaluminum compound solution.
  • Passivation layer forming composition 3A was prepared as a colorless and transparent solution by mixing 2.05 g of the obtained organoaluminum compound solution and 2.00 g of ethylcellulose solution prepared in the same manner as in Example 2A.
  • the content of the ethyl cellulose in the passivation layer forming composition 3A was 5.9%, and the content of the organoaluminum compound was 20.0%.
  • a passivation layer was formed on a pretreated silicon substrate and evaluated in the same manner as in Example 1A, except that the passivation layer forming composition 3A prepared above was used.
  • the effective lifetime was 183 ⁇ s.
  • a solar cell element was produced and evaluated in the same manner as in Example 1A except that the passivation layer forming composition 3A was used instead of the passivation layer forming composition 1A.
  • the evaluation results are shown in Table 1.
  • Example 4A 7.52 g of stearamide and 67.67 g of terpineol were mixed and stirred at 130 ° C. for 1 hour to prepare a stearamide solution.
  • (Ethylacetoacetate) 2.25 g of aluminum isopropoxide, 0.83 g of terpineol, 16.07 g of isobornylcyclohexanol and 1.30 g of stearamide solution were mixed to prepare a composition 4A for forming a passivation layer.
  • the content of stearamide in the passivation layer forming composition 4A was 0.64%, and the content of the organoaluminum compound was 11.0%.
  • a passivation layer was formed on a pretreated silicon substrate and evaluated in the same manner as in Example 1A, except that the passivation layer forming composition 4A prepared above was used.
  • the effective lifetime was 130 ⁇ s.
  • a solar cell element was produced and evaluated in the same manner as in Example 1A except that the passivation layer forming composition 4A was used instead of the passivation layer forming composition 1A.
  • the evaluation results are shown in Table 1.
  • Example 5A In the production of the solar cell element of Example 1A, instead of forming the aluminum electrode by the screen printing method, using an aluminum vapor deposition machine (Sanyu Electronics Co., Ltd., SVC-700TM), it was vapor deposited with a solid pattern of 125 mm ⁇ 125 mm. Produced a solar cell element in the same manner as in Example 1A. The aluminum deposition was performed after the degree of vacuum became 10 ⁇ 4 Pa or less, and the distance between the semiconductor substrate and the deposition source was set to 70 mm and the treatment was performed for 5 minutes. Evaluation was performed in the same manner as in Example 1A, and the evaluation results are shown in Table 1.
  • Example 1A an evaluation substrate was produced in the same manner as Example 1A, except that the passivation layer forming composition 1A was not applied. The effective lifetime of the evaluation substrate was measured and evaluated. The effective lifetime was 20 ⁇ s.
  • Example 1A a solar cell element was produced and evaluated in the same manner as in Example 1A, except that the passivation layer forming composition 1A was not applied. The evaluation results are shown in Table 1.
  • Example 2A A colorless and transparent composition C2 was prepared by mixing 2.01 g of tetraethoxysilane, 1.99 g of terpineol and 4.04 g of an ethylcellulose solution prepared in the same manner as in Example 2A. A passivation layer was formed on a silicon substrate pretreated in the same manner as in Example 1A except that the composition C2 prepared above was used, and evaluated in the same manner. The effective lifetime was 23 ⁇ s.
  • a solar cell element was produced and evaluated in the same manner as in Example 1A except that the composition C2 was used instead of the passivation layer forming composition 1A.
  • the evaluation results are shown in Table 1.
  • Example 1B> (Preparation of Passivation Layer Forming Composition 1B) An organoaluminum compound solution was prepared by mixing 2.00 g of tri-sec-butoxyaluminum and 2.01 g of terpineol (product name: Terpineol-LW, Nippon Terpene Chemical Co., Ltd.). Separately from this, 5.00 g of ethyl cellulose (Nihon Kasei Co., Ltd., Etcelle STD200) and 95.02 g of terpineol were mixed and stirred at 150 ° C. for 1 hour to prepare an ethyl cellulose solution.
  • terpineol product name: Terpineol-LW, Nippon Terpene Chemical Co., Ltd.
  • Passivation layer forming composition 1B was prepared as a colorless and transparent solution by mixing 2.16 g of the obtained organoaluminum compound solution and 3.00 g of ethylcellulose solution.
  • the content rate in the composition 1B for forming a passivation layer of ethyl cellulose was 2.9%, and the content rate of the organoaluminum compound was 21%.
  • Table 2 shows the content of each component. In the description of the composition in Table 2, “-” indicates that it was not added.
  • n-type silicon substrate As the semiconductor substrate, a single crystal n-type silicon substrate (SUMCO, 50 mm square, thickness: 625 ⁇ m) having a mirror-shaped surface was used.
  • the silicon substrate was pre-treated by immersing and cleaning at 70 ° C. for 5 minutes using an RCA cleaning solution (Kanto Chemical Co., Ltd., Frontier Cleaner-A01).
  • the entire surface on one side on the mirror shape side is applied using a screen printing method so that the thickness after drying becomes 5.0 ⁇ m. And dried at 150 ° C. for 3 minutes.
  • heat treatment (firing) was performed at 550 ° C. for 1 hour.
  • the opposite surface of the silicon substrate was treated in the same manner to produce an evaluation substrate in which a passivation layer was formed on both surfaces of the silicon substrate.
  • an X-ray diffractometer (Rigaku Corporation, LAD-2X)
  • the X-ray diffraction pattern of a semiconductor substrate having a passivation layer formed on both sides was measured.
  • no crystallized material other than Si was observed, and crystals were observed in the passivation layer.
  • Activated aluminum oxide was not detected.
  • the evaluation results are shown in Table 2.
  • the measurement conditions in the X-ray diffraction analysis method are as follows.
  • the X-ray diffraction pattern of the silicon substrate on which the passivation layer was formed was measured using an X-ray diffractometer (Rigaku Corporation, LAD-2X).
  • the X-ray source was Cu-K ⁇
  • the output was 40 kV
  • the current was 20 mA
  • the incident slit was 1 °
  • the scattering slit was 1 °
  • the light receiving slit was 0.3 mm
  • the scanning speed was 2 ° min ⁇ 1 .
  • the thickness of the passivation layer of the prepared evaluation substrate was measured using a stylus-type step gauge (AmBios, XP-2) at a speed of 0.1 mm / s and a needle load of 0.5 mg under three conditions to passivate. The average thickness of the layer was calculated. The evaluation results are shown in Table 2. Further, the density of the passivation layer was calculated based on the difference in mass of the semiconductor substrate before application and after heat treatment (firing), and the area and thickness of the passivation layer. The evaluation results are shown in Table 2. In the description of evaluation in Table 2, “-” indicates that it has not been evaluated.
  • the effective lifetime ( ⁇ s) immediately after production (after 1 hour) was measured at room temperature (25 ° C.) using a lifetime measurement device (Nippon Semi-Lab Co., Ltd., WT-2000PVN) It was measured by the reflected microwave photoconductive decay method.
  • the effective lifetime immediately after production of the region to which the composition for forming a passivation layer of the obtained evaluation substrate was applied was 220 ⁇ s.
  • the stability over time was evaluated as follows. The results are shown in Table 2. The stability over time was evaluated by placing an evaluation substrate in a constant temperature and humidity chamber at 50 ° C. and 80% RH, and measuring the effective lifetime in the same manner as described above after storage for 1 month. If the effective lifetime after storage is long, it can be said that the stability over time is excellent. The evaluation results are shown in Table 2.
  • a solar cell element having a structure as shown in FIG. 13 was produced using the composition for forming a passivation layer obtained above.
  • a specific manufacturing method is described below.
  • through holes having a diameter of 100 ⁇ m that penetrated both the light receiving surface and the back surface were formed by a laser drill.
  • a texture and an n + type diffusion layer were formed on the light receiving surface side.
  • the composition for forming a passivation layer was applied to the entire area of the light receiving surface and the area other than the electrode formation scheduled area on the back surface, and dried to form a composition layer. Thereafter, heat treatment (firing) was performed at 550 ° C.
  • a passivation layer Next, an antireflection film was formed on the passivation layer on the light receiving surface.
  • the n + type diffusion layer was also formed in the through hole and part of the back surface (n type diffusion region).
  • a silver electrode paste DuPont, PV159A was diluted 5 times with terpineol into the through-hole formed earlier, filled by an inkjet method, and further printed in a grid on the light-receiving surface side.
  • a silver electrode paste (DuPont, PV159A) was printed in stripes so that a silver electrode paste layer was formed on the through hole in the n-type diffusion region on the back surface derived from the n-type silicon substrate. Specifically, the silver electrode paste was printed in a pattern so as to form the back electrode 20 shown in FIG. Also, aluminum electrode paste (Advantech Co., Ltd., PVG-AD-02) is printed in a pattern so that the back electrode 21 shown in FIG. 12 is formed in a region other than the silver electrode paste layer to form an aluminum electrode paste layer. did. This was subjected to a heat treatment for 10 seconds at a maximum heat treatment (firing) temperature of 800 ° C.
  • the power generation characteristics short circuit current density, open voltage, fill factor, conversion efficiency evaluated.
  • the results are shown in Table 2.
  • the evaluation was performed with a mask so that the light receiving area was 125 mm ⁇ 125 mm.
  • the power generation characteristics were measured according to JIS-C-8913 (fiscal 2005) and JIS-C-8914 (fiscal 2005).
  • save was evaluated.
  • the results are shown in Table 2.
  • the evaluation results are shown in Table 2.
  • Example 2B Trisec-butoxyaluminum (4.79 g), ethyl acetoacetate (2.56 g) and terpineol (4.76 g) were mixed and stirred at 25 ° C. for 1 hour to obtain an organoaluminum compound solution. Separately, 12.02 g of ethyl cellulose and 88.13 g of terpineol were mixed and stirred at 150 ° C. for 1 hour to prepare an ethyl cellulose solution. Next, 2.93 g of an organoaluminum compound solution and 2.82 g of an ethyl cellulose solution were mixed to prepare a passivation layer forming composition 2B as a colorless and transparent solution. The content of ethyl cellulose in the passivation layer forming composition 2B was 5.9%, and the content of the organoaluminum compound was 20.1%.
  • a passivation layer was formed on a pretreated silicon substrate and evaluated in the same manner as in Example 1B, except that the composition 2B for forming a passivation layer prepared above was used.
  • the effective lifetime was 204 ⁇ s.
  • a solar cell element was produced and evaluated in the same manner as in Example 1B except that the passivation layer forming composition 2B was used instead of the passivation layer forming composition 1B.
  • the evaluation results are shown in Table 2.
  • Example 3B Trisec-butoxyaluminum (4.96 g), diethylmalonic acid (3.23 g) and terpineol (5.02 g) were mixed and stirred at 25 ° C. for 1 hour to obtain an organoaluminum compound solution.
  • Passivation layer forming composition 3B was prepared as a colorless and transparent solution by mixing 2.05 g of the obtained organoaluminum compound solution and 2.00 g of ethylcellulose solution prepared in the same manner as in Example 2B.
  • the content of the ethyl cellulose in the passivation layer forming composition 3B was 5.9%, and the content of the organoaluminum compound was 20%.
  • a passivation layer was formed on a pretreated silicon substrate and evaluated in the same manner as in Example 1B, except that the passivation layer forming composition 3B prepared above was used.
  • the effective lifetime was 183 ⁇ s.
  • a solar cell element was produced and evaluated in the same manner as in Example 1B except that the passivation layer forming composition 3B was used instead of the passivation layer forming composition 1B.
  • the evaluation results are shown in Table 2.
  • Example 4B 7.52 g of stearamide and 67.67 g of terpineol were mixed and stirred at 130 ° C. for 1 hour to prepare a stearamide solution.
  • (Ethyl acetoacetate) 2.25 g of aluminum isopropoxide (aluminum ethyl acetate diisopropoxylate), 0.83 g of terpineol, 16.07 g of isobornylcyclohexanol and 1.30 g of stearamide solution were mixed, and the passivation layer A forming composition 4B was prepared.
  • the content of stearamide in the passivation layer forming composition 4B was 0.6%, and the content of the organoaluminum compound was 11.0%.
  • a passivation layer was formed on a pretreated silicon substrate and evaluated in the same manner as in Example 1B, except that the composition 4B for forming a passivation layer prepared above was used.
  • the effective lifetime was 130 ⁇ s.
  • a solar cell element was produced and evaluated in the same manner as in Example 1B except that the passivation layer forming composition 4B was used instead of the passivation layer forming composition 1B.
  • the evaluation results are shown in Table 2.
  • Example 5B A solar cell element having a structure as shown in FIG. 11 was produced using the passivation layer forming composition 1B.
  • an n + -type diffusion layer 12 On the light receiving surface of the n-type semiconductor substrate 11, an n + -type diffusion layer 12, a semiconductor substrate passivation layer 16, and an antireflection film 13 were formed in this order.
  • a back electrode 17 was formed on the n + type diffusion layer 12 (n type diffusion region), and a back electrode 15 was formed on the p + type diffusion layer 14 (p type diffusion region).
  • the semiconductor substrate passivation layer 16 is formed in a region other than the region where the back electrode 15 and the back electrode 17 are formed on the back surface. Evaluation was conducted in the same manner as in Example 1B except that the obtained solar cell element as shown in FIG. 11 was used. The evaluation results are shown in Table 2.
  • Example 1B an evaluation substrate was produced in the same manner as Example 1B, except that the passivation layer forming composition 1B was not applied. The effective lifetime of the evaluation substrate was measured and evaluated. The effective lifetime was 20 ⁇ s.
  • Example 1B a solar cell element was produced and evaluated in the same manner as Example 1B except that the passivation layer forming composition 1B was not applied. The evaluation results are shown in Table 2.
  • Example 2B A colorless and transparent composition C2 was prepared by mixing 2.01 g of tetraethoxysilane, 1.99 g of terpineol and 4.04 g of an ethylcellulose solution prepared in the same manner as in Example 2B. A passivation layer was formed on a silicon substrate pretreated in the same manner as in Example 1B except that the composition C2 prepared above was used, and evaluated in the same manner. The effective lifetime of the evaluation substrate was measured and evaluated. The effective lifetime was 23 ⁇ s.
  • a solar cell element was produced and evaluated in the same manner as in Example 1B, except that the composition C2 was used instead of the passivation layer forming composition 1B.
  • the evaluation results are shown in Table 2.
  • Example 1C [Preparation of semiconductor substrate] (Preparation of passivation layer forming composition 1C) An organoaluminum compound solution was prepared by mixing 2.00 g of trisec-butoxyaluminum and 2.01 g of terpineol (product name: Terpineol-LW) as the organoaluminum compound. Separately, 5.00 g of ethyl cellulose (Nisshinsei Co., Ltd., Etcelle STD200) and 95.02 g of terpineol were mixed and stirred at 150 ° C. for 1 hour to prepare an ethyl cellulose solution.
  • a passivation layer forming composition 1C As a colorless and transparent solution.
  • the content of ethyl cellulose in the passivation layer forming composition 1C was 2.9%, and the content of the organoaluminum compound was 20.9%.
  • Table 3 shows the content of each component. In the description of the composition in Table 3, “-” indicates that it is not added.
  • a single crystal p-type silicon substrate (SUMCO, 50 mm square, thickness: 625 ⁇ m) having a mirror-shaped surface was used.
  • the p-type silicon substrate was pre-treated by immersing and cleaning at 70 ° C. for 5 minutes using an RCA cleaning solution (Kanto Chemical Co., Ltd., Frontier Cleaner-A01).
  • the entire surface on the mirror-shaped side is dried to a thickness of 5.0 ⁇ m using a screen printing method. And dried at 150 ° C. for 3 minutes.
  • heat treatment (baking) at 550 ° C. for 1 hour, the substrate was allowed to cool at room temperature (25 ° C.) to prepare an evaluation substrate.
  • the thickness of the passivation layer in the prepared evaluation substrate was measured at three points using a stylus step meter (AmBios, XP-2) under the conditions of a speed of 0.1 mm / s and a needle load of 0.5 mg.
  • the average thickness was determined as the arithmetic average value.
  • the evaluation results are shown in Table 3.
  • the density of the passivation layer was calculated based on the difference in mass of the semiconductor substrate before application and after heat treatment (firing), and the area and thickness of the passivation layer.
  • the evaluation results are shown in Table 3. In the description of evaluation in Table 3, “-” indicates that it has not been evaluated.
  • the presence or absence of crystallized aluminum oxide was confirmed by X-ray diffraction analysis for the passivation layer of the substrate for evaluation. As a result, no crystallized aluminum oxide was detected, and it was found that all aluminum oxide was amorphous aluminum oxide. It was.
  • the measurement conditions in the X-ray diffraction analysis method are as follows. The X-ray diffraction pattern of the silicon substrate on which the passivation layer was formed was measured using an X-ray diffractometer (Rigaku Corporation, LAD-2X).
  • the X-ray source was Cu-K ⁇ , the output was 40 kV, the current was 20 mA, the incident slit was 1 °, the scattering slit was 1 °, the light receiving slit was 0.3 mm, and the scanning speed was 2 ° min ⁇ 1 .
  • the silicon peak was observed, and no peak derived from crystallized aluminum oxide was observed.
  • the effective lifetime ( ⁇ s) immediately after production (after 1 hour) was measured at room temperature (25 ° C.) using a lifetime measurement device (Nippon Semi-Lab Co., Ltd., WT-2000PVN) It was measured by the reflected microwave photoconductive decay method.
  • the effective lifetime immediately after production of the region to which the composition for forming a passivation layer was applied was 220 ⁇ s.
  • the stability over time was evaluated as follows. The results are shown in Table 3. The stability over time was evaluated by placing an evaluation substrate in a constant temperature and humidity chamber at 50 ° C. and 80% RH, and measuring the effective lifetime in the same manner as described above after storage for 1 month. If the effective lifetime after storage is long, it can be said that the stability over time is excellent. The evaluation results are shown in Table 3.
  • an n-type diffusion layer forming composition was printed under the same conditions as described above, except that it was changed to a 45 mm ⁇ 45 mm solid pattern and subjected to heat treatment.
  • a sample for sheet resistance measurement was prepared.
  • the sheet resistance of this n-type diffusion layer was 40 ⁇ / ⁇ .
  • Sheet resistance was measured with a four-probe measuring device (Mitsubishi Chemical Corporation, Loresta-EP).
  • first n-type diffusion layer After forming the first n-type diffusion layer, heat treatment was performed at 820 ° C. for 20 minutes using phosphorus oxychloride to form a second n-type diffusion layer on both sides.
  • the sheet resistance of the second n-type diffusion layer was 110 ⁇ / ⁇ . Subsequently, it etched with 5% hydrofluoric acid aqueous solution.
  • a SiNx film was formed on the light receiving surface side by plasma enhanced chemical vapor deposition (PECVD) so as to have a thickness of 80 nm.
  • PECVD plasma enhanced chemical vapor deposition
  • screen printing was performed using the passivation layer forming composition 1C obtained above so as to obtain a pattern as shown in FIG. Specifically, the screen mask plate for forming the back electrode having the square opening 60 and the non-opening 61 of 8 mm ⁇ 8 mm shown in FIG. 22 using a plate in which the square-shaped opening 60 is a non-opening portion) in a region other than the region where the back electrode is to be formed so that the thickness after drying the passivation layer forming composition 1C is 5 ⁇ m.
  • heat treatment at 700 ° C. for 10 minutes
  • the mixture was allowed to cool to room temperature (25 ° C.) to form a passivation layer.
  • an aluminum electrode paste (PVG solutions, PVG-AD-02) was screen-printed on the region where the back electrode was to be formed, and the film was printed at 150 ° C. Dried for a minute.
  • a silver electrode paste (DuPont Co., Ltd., PV159A) is formed using a screen mask plate for forming a light receiving surface electrode having an opening with a bus bar width of 1.5 mm and a finger width of 150 ⁇ m as shown in FIG. Was screen-printed and dried at 150 ° C. for 3 minutes. Then, it heat-processed (baking) at 700 degreeC using the tunnel-type baking furnace (Noritake Co., Ltd.), the light-receiving surface electrode and the back surface electrode were formed, and the solar cell element was produced.
  • Example 2C As the organoaluminum compound, 4.79 g of trisec-butoxyaluminum, 2.56 g of ethyl acetoacetate and 4.76 g of terpineol were mixed and stirred at 25 ° C. for 1 hour to obtain an organoaluminum compound solution. Separately, 12.02 g of ethyl cellulose and 88.13 g of terpineol were mixed and stirred at 150 ° C. for 1 hour to prepare an ethyl cellulose solution.
  • a passivation layer forming composition 2C As a colorless and transparent solution.
  • the content ratio of ethyl cellulose in the passivation layer forming composition 2C was 5.9%, and the content ratio of the organoaluminum compound was 20.1%.
  • An evaluation substrate was prepared and evaluated in the same manner as in Example 1C, except that the passivation layer forming composition 2C was used instead of the passivation layer forming composition 1C.
  • the effective lifetime was 204 ⁇ s.
  • a solar cell element was produced in the same manner as in Example 1C except that the passivation layer forming composition 2C was used instead of the passivation layer forming composition 1C, and evaluated in the same manner.
  • the evaluation results are shown in Table 3.
  • Example 3C As the organoaluminum compound, 4.96 g of trisec-butoxyaluminum, 3.23 g of diethylmalonic acid, and 5.02 g of terpineol were mixed and stirred at 25 ° C. for 1 hour to obtain an organoaluminum compound solution.
  • Passivation layer forming composition 3C was prepared as a colorless and transparent solution by mixing 2.05 g of the obtained organoaluminum compound solution and 2.00 g of ethylcellulose solution prepared in the same manner as in Example 2C.
  • the content ratio of ethylcellulose in the composition 3C for forming a passivation layer was 5.9%, and the content ratio of the organoaluminum compound was 20.0%.
  • An evaluation substrate was prepared and evaluated in the same manner as in Example 1C, except that the passivation layer forming composition 3C was used instead of the passivation layer forming composition 1C.
  • the effective lifetime was 183 ⁇ s.
  • a solar cell element was produced in the same manner as in Example 1C except that the passivation layer forming composition 3C was used instead of the passivation layer forming composition 1C, and the solar cell element was similarly evaluated.
  • the evaluation results are shown in Table 3.
  • Example 4C A stearamide solution was prepared by mixing 7.52 g of stearamide and 67.67 g of terpineol and stirring at 130 ° C. for 1 hour. Formation of a passivation layer by mixing 2.25 g of aluminum isopropoxide as an organoaluminum compound, 0.83 g of terpineol, 16.07 g of isobornylcyclohexanol, and 1.30 g of stearamide solution Composition 4C was prepared. The content of stearamide in the composition 4C for forming a passivation layer was 0.6%, and the content of the organoaluminum compound was 11.0%.
  • An evaluation substrate was prepared and evaluated in the same manner as in Example 1C except that the passivation layer forming composition 4C was used instead of the passivation layer forming composition 1C.
  • the effective lifetime was 130 ⁇ s.
  • Example 3 a solar cell element was produced and evaluated in the same manner as in Example 1C except that the passivation layer forming composition 4C was used instead of the passivation layer forming composition 1C.
  • the evaluation results are shown in Table 3.
  • Example 5C In the production of the solar cell element of Example 1C, instead of forming the aluminum electrode by the screen printing method, an aluminum vapor deposition machine (Sanyu Electronics Co., Ltd., SVC-700TM) was used for vapor deposition with a solid pattern of 125 mm ⁇ 125 mm. Produced a solar cell element in the same manner as in Example 1C. The aluminum deposition was performed after the degree of vacuum became 10 ⁇ 4 Pa or less, and the distance between the semiconductor substrate and the deposition source was set to 70 mm and the treatment was performed for 5 minutes. Evaluation was performed in the same manner as in Example 1C, and the evaluation results are shown in Table 3.
  • SVC-700TM anyu Electronics Co., Ltd., SVC-700TM
  • Example 1C an evaluation substrate was produced in the same manner as in Example 1C, except that the passivation layer forming composition 1C was not applied.
  • the effective lifetime was 20 ⁇ s.
  • Example 1C a solar cell element was produced and evaluated in the same manner as in Example 1C except that the passivation layer forming composition 1C was not applied. The evaluation results are shown in Table 3.
  • composition C2 was prepared by mixing 2.01 g of tetraethoxysilane, 1.99 g of terpineol, and 4.04 g of an ethylcellulose solution prepared in the same manner as in Example 2C.
  • An evaluation substrate was prepared and evaluated in the same manner as in Example 1C except that the composition C2 was used instead of the passivation layer forming composition 1C.
  • the effective lifetime was 23 ⁇ s.
  • a solar cell element was prepared and evaluated in the same manner as in Example 1C except that the composition C2 was used instead of the passivation layer forming composition 1C.
  • the evaluation results are shown in Table 3.
  • the solar cell element of the present invention has excellent conversion efficiency and suppresses deterioration of solar cell characteristics over time.
  • a semiconductor substrate passivation layer having an excellent passivation effect can be formed by using a composition for forming a semiconductor substrate passivation layer containing an organoaluminum compound, and a solar cell element produced using the semiconductor substrate passivation layer exhibits high conversion efficiency.
  • the semiconductor substrate passivation layer can be formed in a desired shape by a simple process.

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