JP2013008942A - Material for passivation film formation for semiconductor substrate, passivation film for semiconductor substrate and manufacturing method thereof, and solar cell element and manufacturing method thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a material for passivation film formation for a semiconductor substrate, allowing formation of a passivation film for a semiconductor substrate having an excellent passivation characteristic with a simple technique; and a passivation film for a semiconductor substrate formed using the material for passivation film formation for a semiconductor substrate and a manufacturing method thereof.SOLUTION: A material for passivation film formation for a semiconductor substrate comprises a polymeric compound having an anionic group or a cationic group. A passivation film 6 for a semiconductor substrate is manufactured by coating the above material for passivation film formation for a semiconductor substrate on a semiconductor substrate 1 to form a coating layer, which is then dried to give a coated film.

Description

  The present invention relates to a semiconductor substrate passivation film forming material, a semiconductor substrate passivation film and a manufacturing method thereof, a solar cell element and a manufacturing method thereof.

The manufacturing process of the conventional silicon solar cell will be described.
First, a p-type silicon substrate having a textured structure is prepared so as to promote the light confinement effect and increase the efficiency, and subsequently, 800 ° C. to 900 ° C. in a mixed gas atmosphere of phosphorus oxychloride (POCl ₃ ), nitrogen, and oxygen. An n-type diffusion layer is uniformly formed by performing several tens of minutes at a temperature. In this conventional method, since phosphorus is diffused using a mixed gas, n-type diffusion layers are formed not only on the surface but also on the side surface and the back surface. Therefore, side etching is performed to remove the n-type diffusion layer on the side surface. Further, the back surface of the n-type diffusion layer must be converted into the p ⁺ -type diffusion layer, an aluminum paste is printed on the back, by firing this, the n-type diffusion layer at the same time as the p ⁺ -type diffusion layer , Got ohmic contact.

  However, since the aluminum layer formed from the aluminum paste has low electrical conductivity, the aluminum layer usually formed on the entire back surface must have a thickness of about 10 μm to 20 μm after firing in order to reduce sheet resistance. Furthermore, since the thermal expansion coefficients of silicon and aluminum differ greatly, a large internal stress is generated in the silicon substrate during the firing and cooling processes, causing damage to crystal boundaries, increasing crystal defects, and warping.

In order to solve this problem, there is a method of reducing the amount of aluminum paste applied and thinning the back electrode layer. However, when the amount of aluminum paste applied is reduced, the amount of aluminum diffusing from the surface of the p-type silicon semiconductor substrate becomes insufficient. As a result, the desired BSF (Back Surface Field) effect (the effect of improving the collection efficiency of the generated carriers due to the presence of the p ⁺ -type diffusion layer) cannot be achieved, resulting in a problem that the characteristics of the solar cell deteriorate. .

In relation to the above, there has been proposed a point-contant method in which an aluminum paste is applied to a part of the silicon substrate surface to partially form a p ⁺ layer and an aluminum electrode (for example, see Patent Document 1). .
In the case of a solar cell having a point contact structure on the side opposite to the light receiving surface (hereinafter also referred to as “back side”), it is necessary to suppress the recombination rate of minority carriers on the surface of the portion other than the aluminum electrode. is there. For this purpose, a SiO ₂ film or the like has been proposed as a back-side passivation film (see, for example, Patent Document 2). This is to reduce the surface state density that causes recombination by terminating the dangling bonds of silicon atoms on the back surface layer of the silicon substrate by forming an oxide film.

In addition, a method has been proposed in which a SiN _x (silicon nitride) film widely used as an antireflection film on the light receiving surface side is also used as a passivation film for the back surface (see, for example, Patent Document 3).

Japanese Patent No. 3107287 Japanese Patent Laid-Open No. 2004-6565 JP 2010-537423 A

However, the SiO ₂ film and the SiN _x film proposed in Patent Document 2 and Patent Document 3 are generally formed using a thermal oxidation method or a CVD method. In the thermal oxidation method, high-temperature treatment at 1000 ° C. or higher is usually required, and process conditions such as gas flow rate and gas flow rate distribution must be managed. When using a CVD apparatus, depending on the type of reactive gas used, the hydrogen passivation effect may be expected due to the decomposition of the reactive gas. However, the cost of the manufacturing apparatus is low due to low throughput and frequent apparatus maintenance. There was a problem of being expensive. Furthermore, since the photolithography process is usually used for forming the opening of the passivation film for the back surface, there are problems in the number of processes and the apparatus cost.

  The present invention has been made in view of the above conventional problems, and provides a passivation film forming material for a semiconductor substrate capable of forming a passivation film for a semiconductor substrate having excellent passivation characteristics by a simple method. Let it be an issue. It is another object of the present invention to provide a semiconductor substrate passivation film formed using the semiconductor substrate passivation film forming material and a method of manufacturing the same.

Specific means for solving the above problems are as follows.
<1> A material for forming a passivation film for a semiconductor substrate, comprising a polymer compound having an anionic group or a cationic group.

<2> The polymer compound according to <1>, wherein the polymer compound has a main chain composed of a carbon atom and at least one atom selected from the group consisting of a hydrogen atom, a fluorine atom, an oxygen atom, and a sulfur atom. A material for forming a passivation film for a semiconductor substrate.

<3> The material for forming a passivation film for a semiconductor substrate according to <1> or <2>, wherein the polymer compound has an aromatic group.

<4> The material for forming a passivation film for a semiconductor substrate according to any one of <1> to <3>, wherein the conductivity of the polymer compound is 1 mS / cm or more in water at 25 ° C.

<5> The <1> to <4>, wherein the polymer compound has at least one anionic group selected from the group consisting of a sulfonic acid group, a carboxy group, a phosphoric acid group, a phosphonic acid group, and a phenolic hydroxyl group. The material for forming a passivation film for a semiconductor substrate according to any one of the above.

<6> Any of the above <1> to <5>, wherein the polymer compound is at least one selected from the group consisting of a polyperfluoroolefin sulfonic acid derivative, a sulfonated polystyrene derivative, and a sulfonated polyarylethersulfone. 2. A material for forming a passivation film for a semiconductor substrate according to item 1.

<7> The material for forming a passivation film for a semiconductor substrate according to any one of <1> to <6>, further including a filler.

<8> The material for forming a passivation film for a semiconductor substrate according to <7>, wherein the filler is an inorganic filler.

<9> The _{filler, Al 2 O 3, SiO 2} , ZrO 2, TiO 2, SiC, MgO, zeolite, according to claim 7 or said at least one selected from the group consisting of AlN and BN to <8> The material for forming a passivation film for a semiconductor substrate as described.

<10> The material for forming a passivation film for a semiconductor substrate according to any one of <7> to <9>, wherein the filler has a weight average particle diameter (50% D) of 10 nm to 30 μm.

<11> The material for forming a passivation film for a semiconductor substrate according to any one of <1> to <10>, further including a dispersion medium.

<12> The semiconductor substrate passivation film forming material according to <11>, wherein the dispersion medium includes at least one selected from the group consisting of methanol, ethanol, 1-propanol, and 2-propanol.

<13> A passivation film for a semiconductor substrate which is provided on a semiconductor substrate and is a coating film of the material for forming a passivation film for a semiconductor substrate according to any one of <1> to <12>.

<14> Applying the semiconductor substrate passivation film forming material according to any one of <1> to <12> on the semiconductor substrate to form a coating layer; and drying the coating layer. Forming a coating film, and a method for producing a passivation film for a semiconductor substrate.

<15> The method for producing a passivation film for a semiconductor substrate according to <14>, further including a step of applying a hydrofluoric acid aqueous solution onto the semiconductor substrate before the step of forming the coating layer.

<16> A solar cell element having a semiconductor substrate having a pn junction, an electrode, and the passivation film for a semiconductor substrate according to <13> provided on the semiconductor substrate.

The manufacturing method of the solar cell element which has the process of forming the passivation film for semiconductor substrates as described in said <13> on the semiconductor substrate which has a <17> pn junction and was provided with the electrode.

  According to the present invention, it is an object to provide a passivation film forming material for a semiconductor substrate capable of forming a passivation film for a semiconductor substrate having excellent passivation characteristics by a simple technique. In addition, a semiconductor substrate passivation film formed using the semiconductor substrate passivation film forming material and a method of manufacturing the same can be provided.

It is sectional drawing which shows typically an example of the manufacturing method of the solar cell element which has the passivation film for semiconductor substrates concerning this embodiment. It is sectional drawing which shows typically an example of the manufacturing method of the solar cell element which has the passivation film for semiconductor substrates concerning this embodiment. It is sectional drawing which shows typically the back surface electrode type solar cell element which has the passivation film for semiconductor substrates concerning this embodiment.

  In this specification, the term “process” is not limited to an independent process, and is included in the term if the intended action of the process is achieved even when it cannot be clearly distinguished from other processes. . In the present specification, 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. Further, in the present specification, the content of each component in the composition is 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. Means.

<Material for forming a passivation film for a semiconductor substrate>
The material for forming a passivation film for a semiconductor substrate of the present invention contains at least one polymer compound having an anionic group or a cationic group (hereinafter also referred to as “specific resin”), and, if necessary, a filler, a dispersion It is comprised including other components, such as a medium.
By providing a semiconductor substrate with a material for forming a passivation film for a semiconductor substrate containing at least one of a polymer compound having an anionic group and a polymer compound having a cationic group to form a coating film, an excellent surface passivation effect Can be formed in a desired region by a simple method.

This can be considered as follows, for example.
It is considered that the defect can be terminated by a reaction or interaction between a defect present on the surface of the semiconductor substrate and an anion group which is a dissociative group or an ion dissociated from the cationic group. For example, it is considered that a dangling bond can be terminated by a reaction between a proton dissociated from a proton type anionic group and a dangling bond. Further, it is considered that the defect can be terminated by accepting the cationic group dissociated from the electron in the defect.

  In this specification, the surface passivation effect can be evaluated by measuring the effective lifetime of minority carriers in a semiconductor substrate provided with a semiconductor substrate passivation film by the reflection microwave conductive attenuation method.

Here, the effective lifetime τ is expressed by the following equation (I) by the bulk lifetime τ _b inside the silicon substrate and the surface lifetime τ _s of the silicon substrate surface. When the surface state density on the surface of the silicon substrate is small, τ _s increases, and as a result, the effective lifetime τ increases. Further, even if defects such as dangling bonds in the silicon substrate are reduced, the bulk lifetime τ _b is increased and the effective lifetime τ is increased. That is, by measuring the effective lifetime τ, the interface characteristics of the passivation film / silicon substrate and the internal characteristics of the semiconductor substrate such as dangling bonds can be evaluated.
1 / τ = 1 / τ _b + 1 / τ _s (I)
It is known that the longer the effective lifetime is, the slower the recombination rate of minority carriers is, and it is generally known that conversion efficiency is improved when a silicon substrate is used as a solar cell, for example.

In the present invention, a passivation film for a semiconductor substrate can be formed on a semiconductor substrate by applying a polymer compound having an anionic group or a polymer compound having a cationic group onto the semiconductor substrate to form a coating film. it can.
Further, in the semiconductor substrate passivation film forming material, it is preferable to select a polymer compound for forming a semiconductor substrate passivation film according to the type of the fixed charge of the dopant present on the surface and inside of the semiconductor substrate. Specifically, a polymer compound having a positive fixed charge is preferably selected for the surface of the semiconductor substrate having an n-type layer or an n ⁺ -type diffusion layer on the surface. On the other hand, it is preferable to select a polymer compound having a negative fixed charge for the surface of the semiconductor substrate having a p-type layer or a p ⁺ -type diffusion layer on the surface.
By selecting in this way, minority carriers can be repelled from the field effect caused by band bending, and for example, the solar cell element can be further improved in efficiency.

In addition, when the fixed charge is small, for example, when the interface fixed charge density is about 10 ⁷ cm ⁻² to 10 ¹² cm ⁻² , the effect of band bending due to the fixed charge at the interface between the passivation film and the semiconductor substrate is reduced. Therefore, a polymer compound for forming a passivation film for a semiconductor substrate can be selected regardless of the type of fixed charge.
The fixed charge present in the polymer compound is formed by depositing a passivation film on an arbitrary silicon substrate, and then depositing it with an aluminum electrode masked to an arbitrary size, for example, a diameter of 1 mm. It can be calculated from the curve.

[Polymer compound]
The polymer compound (specific resin) having an anionic group or a cationic group is a compound having a main chain constituting the polymer compound and a side chain having an anionic group or a cationic group bonded to the main chain. If there is no particular limitation, it can be appropriately selected from commonly used polymer compounds. The polymer compound having an anionic group or a cationic group may be either a polymer or an oligomer.
Furthermore, the specific resin may be used as, for example, an ion exchange resin.

The main chain in the specific resin is not particularly limited, and may be a hydrocarbon main chain or a fluorocarbon main chain.
Examples of the oligomer or polymer constituting the hydrocarbon main chain include polyether ketone, polysulfide, polyphosphazene, polyphenylene, polybenzimidazole, polyether sulfone, polyaryl ether sulfone, polyphenylene oxide, polycarbonate, polyurethane, polyamide, polyimide, Polyurea, polysulfone, polysulfonate, polybenzoxazole, polybenzothiazole, polythiazole, polyphenylquinoxaline, polyquinoline, polysiloxane, polytriazine, polydiene, polypyridine, polypyrimidine, polyoxathiazole, polytetrazapyrene, polyoxazole, Polyvinylpyridine, polyvinylimidazole, polypyrrolidone, polyacrylate derivatives, polymethacrylate derivatives Body, polystyrene derivatives and the like.

  As the oligomer or polymer constituting the hydrocarbon main chain, polyether ketone, polysulfide, polyphosphazene, polyphenylene, polybenzimidazole, polyether sulfone, polyaryl ether sulfone, polyphenylene oxide, polycarbonate, polyurethane, polyamide, polyimide , Polyurea, polysulfone, polysulfonate, polybenzoxazole, polybenzothiazole, polyphenylquinoxaline, polyquinoline, polytriazine, polydiene, polypyridine, polyoxathiazole, polyacrylate derivative, polymethacrylate derivative, polystyrene derivative and the like. More preferably, polyetherketone, polysulfide, polyphosphazene, polyphenylene, polybenzimidazole, polyethersulfone, polyphenylene oxide, polycarbonate, polyamide, polyimide, polyurea, polysulfone, polysulfonate, polybenzoxazole, polybenzothiazole, polyphenyl Examples thereof include quinoxaline, polyquinoline, polytriazine, polydiene, polyacrylate derivative, polymethacrylate derivative, polystyrene derivative, and phenol resin derivative.

  Polymers and oligomers constituting the fluorocarbon main chain include polyperfluoroolefin resins such as polyperfluoroethylene, polyperfluoropropene and polyperfluoroalkoxyalkene, and a part of fluorine atoms of polyperfluoroolefin resin. And polyfluoroolefin resin in which is substituted with a hydrogen atom.

The main chain in the specific resin is at least one selected from the group consisting of a carbon atom, a hydrogen atom, a fluorine atom, an oxygen atom, and a sulfur atom from the viewpoint of surface passivation effect and ease of production of the corresponding polymer compound. The main chain is preferably composed of a seed atom, and is a main chain composed of a carbon atom and at least one atom selected from the group consisting of a hydrogen atom, an oxygen atom and a sulfur atom. More preferably, the main chain is composed of a carbon atom and at least one atom selected from the group consisting of a hydrogen atom, an oxygen atom and a sulfur atom, and has an aromatic group.
Further, the main chain in the specific resin is also preferably a main chain composed of carbon atoms and fluorine atoms from the viewpoint of surface passivation effect and chemical durability.

  Specific examples of the main chain in the specific resin include polystyrene derivatives such as styrene-olefin copolymers and polystyrene, polyaryl ether sulfones, polyether ketones, polyamides, polyimides, and polyperfluoroolefins. It is preferably at least one selected from the group consisting of styrene-olefin copolymers, polystyrene derivatives such as polystyrene, polyaryl ether sulfones, and polyperfluoroolefins.

The specific resin preferably has a structure in which a side chain having an anionic group or a cationic group is bonded to the main chain. The aspect in which the side chain having an anionic group and a cationic group is bonded to the main chain is not particularly limited, and even if the anionic group and the cationic group are directly bonded to the main chain, the anionic group and the cationic group The mode which a group couple | bonds with a principal chain through a bivalent coupling group may be sufficient.
In the case where the anionic group and the cationic group are bonded to the main chain via a divalent linking group, the divalent linking group can be connected to the anionic group or cationic group and the main chain. There is no particular limitation. The divalent linking group is preferably composed of at least one selected from the group consisting of a carbon atom, a hydrogen atom, a fluorine atom and an oxygen atom, for example.
Specific examples of the divalent linking group include an alkylene group, an alkyleneoxy group, an arylene group, an aryleneoxy group, a perfluoroalkylene group, a perfluoroalkyleneoxy group, and combinations thereof.

  The anionic group in the polymer compound having an anionic group is preferably at least one selected from the group consisting of a sulfonic acid group, a carboxy group, a phosphoric acid group, a phosphonic acid group, and a phenolic hydroxyl group. More preferably, it is at least one selected from the group consisting of an acid group, a carboxy group and a phosphoric acid group, and more preferably a sulfonic acid group. With such an anionic group, a fixed charge can be efficiently imparted to the passivation film for a semiconductor substrate.

A sulfonic acid group, a carboxy group, a phosphonic acid group, a phosphoric acid group and a phenolic hydroxyl group, each specifically _{^{-SO 3 - X +, -COO -}} X +, -PO 3 2- X + Y + , -OPO ₃ ² -X ⁺ Y ⁺ , and -Ar-O ^- X ⁺ are preferred.
In the above formula, X ⁺ and Y ⁺ are each independently a proton (H ⁺ ), a monovalent metal cation, NH ₄ ⁺ , NH ₃ R ⁺ , NH ₂ R ₂ ⁺ , NHR ₃ ⁺ , NR ₄ ^+. Or a pyridinium ion, each R independently represents an alkyl group or an aryl group, and a plurality of R may be the same or different. Ar represents an arylene group.

Among the functional groups, the polymer compound having an anionic group is preferably a polymer compound having at least a sulfonic acid group, and is a polymer compound having a proton type sulfonic acid group (—SO ₃ H group). More preferably.
Although the detailed reason is unclear, when the passivation film forming material for a semiconductor substrate contains at least a polymer compound having a sulfonic acid group, a more excellent passivation effect tends to be obtained. This can be considered as follows, for example.

  In general, since sulfonic acid groups have a high degree of ion dissociation and high electrical conductivity, they are also suitably used as proton conducting electrolyte membranes for solid polymer and direct methanol fuel cells. Such a high degree of ion dissociation reacts with defects present in the semiconductor substrate and on the surface of the semiconductor substrate to reduce the number of recombination centers present in the semiconductor substrate, and thus is considered to exhibit an excellent passivation effect. In particular, it is considered that a dangling bond and a proton react and a dangling bond can be terminated efficiently by using a proton conduction type. Further, when the semiconductor substrate is washed with a hydrofluoric acid aqueous solution or the like before forming the semiconductor substrate passivation film, it is considered that dangling bonds form Si—H bonds by hydrofluoric acid treatment. After the hydrofluoric acid treatment, it is considered that the formed Si—H bond is stabilized by being covered with a polymer compound having a sulfonic acid group.

  The polymer compound having an anionic group in the present invention is a polyperfluoroolefin sulfonic acid derivative such as Nafion (registered trademark, manufactured by DuPont) or Flemion (registered trademark) from the viewpoint of surface passivation effect and adhesion to a semiconductor substrate. Manufactured by Asahi Glass Co., Ltd.), sulfonated polystyrene derivatives such as sulfonated polystyrene and sulfonated styrene-olefin copolymer, sulfonated polyether ketone, sulfonated polyamide, sulfonated polyimide, and sulfone. Preferably, at least one selected from sulfonated polyarylethersulfone, and a small amount selected from polyperfluoroolefin sulfonic acid derivatives, sulfonated polystyrene derivatives and sulfonated polyarylethersulfones. More preferably Kutomo one.

  The cationic group in the polymer compound having a cationic group is preferably at least one selected from the group consisting of a pyridinium group, an alkylammonium group, and an imidazolium group. By being such a cationic group, a fixed charge can be efficiently imparted to the passivation film for a semiconductor substrate.

  Examples of such a high molecular compound having a cationic group include quaternary ammonium-treated poly-4-vinylpyridine, poly-2-vinylpyridine, poly-2-methyl-5-vinylpyridine, and poly-1. -Pyridin-4-ylcarbonyloxyethylene and the like. Here, the quaternary ammoniumation treatment of poly-4-vinylpyridine can be performed by reacting poly-4-vinylpyridine with an alkyl halide such as methyl bromide or ethyl bromide. In addition, a polymer compound having a cationic group can be obtained by polymerizing a quaternary ammonium monomer such as an ammonium vinyl monomer or an imidazolium vinyl monomer.

  The content of the anionic group and the cationic group contained in the polymer compound (specific resin) having an anionic group or a cationic group can be appropriately selected according to the purpose. Among these, from the viewpoint of the surface passivation effect, the specific resin preferably has a conductivity of 1 mS / cm or more in pure water at 25 ° C., and preferably has a content of 4 mS / cm to 30 mS / cm. Is more preferable. When the conductivity of the specific resin is 1 mS / cm or more, a sufficient passivation effect tends to be obtained, and when it is 30 mS / cm or less, it tends to be chemically stable, and good durability is obtained.

In addition, the electrical conductivity of specific resin is measured as follows. When the specific resin is insoluble in water, the specific resin is processed into a strip-shaped film sample, a platinum plate is pressed on both sides of the obtained film sample, and immersed in pure water at 25 ° C., with a frequency of 0.1 Hz. From 1 to 1 MHz, the resistance between the electrodes is measured from the Cole-Cole plot. By applying the measured resistance (resistance gradient) to the following formula (1), the conductivity of the specific resin can be calculated.
Conductivity [S · cm ⁻¹ ] = 1 / (film width [cm] × film thickness [cm] × resistance interelectrode gradient [Ω · cm ⁻¹ ]) (Formula 1)

Moreover, when specific resin is water-soluble, the electrical conductivity of specific resin can be measured by making specific resin into the state of aqueous solution. In that case, the density | concentration in water of specific resin shall be 5 mass%-20 mass%, and it measures at 25 degreeC using an electric conductivity meter.
Here, the specific resin is water-insoluble means that the solubility in pure water at 25 ° C. is less than 3% by mass, and the specific resin is water-soluble means that the solubility in pure water at 25 ° C. Means 3% by mass or more.

  The content of the anionic group and the cationic group contained in the polymer compound (specific resin) having an anionic group or a cationic group can be appropriately selected according to the purpose. Among these, from the viewpoint of the surface passivation effect, the ion exchange capacity of the polymer compound is preferably 0.01 mmol / g to 10 mmol / g, and more preferably 0.1 mmol / g to 5 mmol / g. When the ion exchange capacity of the polymer compound having an anionic group or a cationic group contained in the material for forming a passivation film is 0.01 mmol / g or more, a sufficient passivation effect is easily obtained.

The molecular weight of the specific resin is not particularly limited and can be appropriately selected according to the purpose. The molecular weight is preferably 100 or more and 1,000,000 or less, more preferably 500 to 500,000, and still more preferably 1000 to 300,000 as a weight average molecular weight. When the weight average molecular weight is 1000000 or less, processability is improved, and a more uniform surface passivation effect can be obtained.
In addition, the weight average molecular weight of specific resin is measured by a conventional method using gel permeation chromatography (GPC) (converted with a calibration curve using standard polystyrene).

The specific resin can be produced as a polymer compound having a desired structure by a conventional method. Moreover, you may use resin marketed as an ion exchange resin.
Hereinafter, the manufacturing method of specific resin is demonstrated.

  The polymer compound having an anionic group can be produced, for example, by polymerizing a monomer composition containing a monomer having an anionic group and a monomer having no anionic group as necessary. it can.

  For example, when a polymer compound having a sulfonic acid group is produced, the sulfonating agent used for producing the sulfonic acid group-containing monomer is not particularly limited. For example, concentrated sulfuric acid, fuming sulfuric acid, Chlorosulfuric acid, an anhydrous sulfuric acid complex, etc. can be used conveniently.

  Production of the sulfonic acid group-containing monomer can be carried out by using these reagents and appropriately selecting reaction conditions according to the compound structure.

  Further, in addition to these sulfonating agents, sulfonating agents described in Japanese Patent No. 2884189, namely 1,3,5-trimethylbenzene-2-sulfonic acid, 1,3,5-trimethylbenzene-2 , 4-disulfonic acid, 1,2,4-trimethylbenzene-5-sulfonic acid, 1,2,4-trimethylbenzene-3-sulfonic acid, 1,2,3-trimethylbenzene-4-sulfonic acid, 1, 2,3,4-tetramethylbenzene-5-sulfonic acid, 1,2,3,5-tetramethylbenzene-4-sulfonic acid, 1,2,4,5-tetramethylbenzene-3-sulfonic acid, 1 , 2,4,5-tetramethylbenzene-3,6-disulfonic acid, 1,2,3,4,5-pentamethylbenzene-6-sulfonic acid, 1,3,5-triethylbenzene-2-sulfone 1-ethyl-3,5-dimethylbenzene-2-sulfonic acid, 1-ethyl-3,5-dimethylbenzene-4-sulfonic acid, 1-ethyl-3,4-dimethylbenzene-6-sulfonic acid, 1 -Ethyl-2,5-dimethylbenzene-3-sulfonic acid, 1,2,3,4-tetraethylbenzene-5-sulfonic acid, 1,2,4,5-tetraethylbenzene-3-sulfonic acid, 1,2 , 3,4,5-pentaethylbenzene-6-sulfonic acid, 1,3,5-triisopropylbenzene-2-sulfonic acid, 1-propyl-3,5-dimethylbenzene-4-sulfonic acid, etc. Is possible.

  Among the sulfonating agents described above, compounds in which a lower alkyl is substituted at both ortho positions of the sulfonic acid group, such as 1,3,5-trimethylbenzene-2-sulfonic acid, 1,2,4,5-tetra Methylbenzene-3-sulfonic acid, 1,2,3,5-tetramethylbenzene-4-sulfonic acid, 1,2,3,4,5-pentamethylbenzene-6-sulfonic acid, 1,3,5- Trimethylbenzene-2,4-disulfonic acid, 1,3,5-toluethylbenzene-2-sulfonic acid, and the like are particularly preferable, and 1,3,5-trimethylbenzene-2-sulfonic acid is most preferable.

  The monomer raw material for producing the sulfonic acid group-containing monomer is not particularly limited as long as it has a polymerizable group and a sulfonateable functional group in the molecule. For example, styrene, divinylbiphenyl, divinylbenzene, methylstyrene, dimethylstyrene, trimethylstyrene, and the like can be given.

When manufacturing a sulfonic acid group containing monomer, it is preferable to add these sulfonating agents in the range of 30 parts by mass to 5000 parts by mass with respect to 100 parts by mass of the monomer raw material, and 50 parts by mass to 2000 parts by mass. If it adds in the range, it is still more preferable.
When the addition amount of the sulfonating agent is 30 parts by mass or more, the sulfonation reaction tends to proceed sufficiently. Further, when the addition amount of the sulfonating agent is 5000 parts by mass or less, the sulfonating agent treatment after the reaction tends to be easy.

The organic solvent used for sulfonation of the monomer raw material is not particularly limited, and any conventionally known one can be used as long as it does not adversely affect the sulfonation reaction.
Specific examples include halogenated aliphatic hydrocarbons such as chloroform, dichloromethane, 1,2-dichloroethane, trichloroethane, tetrachloroethane, trichloroethylene, and tetrachloroethylene; halogenated aromatic hydrocarbons such as dichlorobenzene and trichlorobenzene, nitromethane, Nitro compounds such as nitrobenzene; alkylbenzenes such as trimethylbenzene, tributylbenzene, tetramethylbenzene and pentamethylbenzene; heterocyclic compounds such as sulfolane; linear, branched or cyclic such as octane, decane and cyclohexane Aliphatic saturated hydrocarbons; aprotic electrodes such as N, N-dimethylacetamide, N, N-dimethylformamide, dimethyl sulfoxide, N-methyl-2-pyrrolidone, hexamethylphosphonamide Solvent; methanol, alcohol solvents such as ethanol; phenol, phenolic solvents such as cresol; may be selected as appropriate from such but not limited thereto.

  These solvents may be used alone or in combination of two or more, and the amount used is appropriately selected. Usually, it is preferably in the range of 100 parts by mass to 2000 parts by mass with respect to 100 parts by mass of the sulfonating agent. When the amount of the solvent is 100 parts by mass or more, the sulfonation reaction tends to proceed more uniformly. When the amount of the solvent is 2000 parts by mass or less, separation of the solvent after the reaction from the sulfonating agent and recovery of the solvent tend to be facilitated.

  The sulfonation reaction can be performed, for example, at a reaction temperature in the range of −20 ° C. to 150 ° C. and in a reaction time of 0.5 hours to 50 hours. Here, if the reaction temperature is −20 ° C. or higher, the sulfonation reaction proceeds efficiently. Further, when the reaction temperature is 150 ° C. or lower, it tends to be easy to introduce a sulfonic acid group only into a specific aromatic ring. Further, a polymer compound having no sulfonic acid group may be directly sulfonated. For example, polystyrene, polyaryl ether sulfone, polyether ketone, polyimide, and polyamide are dispersed in concentrated sulfuric acid or contacted with fuming sulfuric acid, and the reaction temperature is in the range of −20 ° C. to 120 ° C., the reaction time is 0.5 hours to 50 hours. Sulfonation can be performed over a range of time.

  On the other hand, when synthesizing a polymer compound having a carboxy group, a phosphonic acid group, or a phosphoric acid group, it is preferably synthesized from a monomer having a carboxy group, a phosphonic acid group, or a phosphoric acid group. Moreover, when synthesizing a polymer compound having a phenolic hydroxyl group, it is preferable to synthesize phenol or a phenol derivative as a monomer.

When producing a polymer compound having an anionic group, a monomer having no anionic group can be used in combination. The monomer having no anionic group is not particularly limited as long as it can be polymerized with a monomer having an anionic group, and can be appropriately selected according to the monomer having an anionic group.
Specific examples include styrene, vinyl acetate, biphenyl derivatives, phenyl ether derivatives, and benzene derivatives.

The method for polymerizing a monomer composition containing at least a monomer having an anionic group is not particularly limited, and can be appropriately selected according to the constitution of the monomer composition.
For example, the monomer composition can be polymerized by a conventional method using a thermal polymerization initiator or the like to produce a polymer compound having an anionic group.

  As a method for purifying a polymer compound having an anionic group obtained by polymerizing a monomer composition containing at least a monomer having an anionic group, a conventionally known purification method can be suitably used. For example, when the obtained polymer compound having an anionic group is solid, it can be purified by washing with a solvent after filtration and drying. Further, when the obtained polymer compound having an anionic group is oily, it can be purified by liquid separation. Further, when the obtained polymer compound having an anionic group is dissolved in the reaction solution, it can be purified by evaporating and removing the organic solvent.

  Alternatively, water is added to a reaction solution containing a polymer compound having an anionic group obtained by polymerizing a monomer composition containing at least a monomer having an anionic group, and if necessary, an alkali component is added and dissolved. After separating into a solvent phase and an aqueous phase, it can be purified by precipitation from the aqueous phase by a method such as acid precipitation or salting out, and after washing with a solvent and drying.

  Further, the polymer compound having an anionic group includes a monomer having an anionic group and having two or more functional groups capable of substitution reaction, and a monomer having two or more functional groups capable of substitution reaction with the monomer. Can also be produced by a condensation reaction.

  When a polymer compound having an anionic group is produced by a condensation reaction, it can be produced in a solvent in the presence of a catalyst. The catalyst amount can be 0.1 to 100 times the total number of moles of monomers to be reacted. The reaction temperature is 0 ° C to 350 ° C, preferably 40 ° C to 260 ° C. The reaction can be conducted for 2 hours to 500 hours.

  As mentioned above, although the manufacturing method of the high molecular compound which has an anionic group was demonstrated, it replaced with the monomer which has an anionic group, and manufactured the high molecular compound which has a cationic group similarly by using the monomer which has a cationic group. can do.

  It is preferable that the material for forming a passivation film for a semiconductor substrate includes one of a polymer compound having an anionic group and a polymer compound having a cationic group. Each of the polymer compound having an anionic group and the polymer compound having a cationic group contained in the material for forming a passivation film for a semiconductor substrate may be a single type or a combination of two or more types.

  The content of the polymer compound having an anionic group or the polymer compound having a cationic group in the material for forming a passivation film for a semiconductor substrate is in the total mass (100 parts by mass) of the material for forming a passivation film for a semiconductor substrate. It is preferably 0.1 to 95 parts by mass, more preferably 1 to 80 parts by mass, and further preferably 3 to 50 parts by mass. When the content is 0.1 part by mass or more, a passivation effect can be sufficiently exhibited as a semiconductor substrate passivation film.

[Filler]
The material for forming a passivation film for a semiconductor substrate preferably contains at least one filler. There is a tendency that the mechanical strength, moisture retention, reflectance, and heat resistance of the passivation film for a semiconductor substrate formed by including a filler can be further improved, and the semiconductor substrate on which the passivation film is formed is processed at a high temperature. It tends to be able to maintain the passivation effect even after it is done. The filler is not particularly limited, and may be an organic filler or an inorganic filler. Especially, it is preferable that a filler is an inorganic filler from a mechanical strength, moisture retention, a reflectance, and a heat resistant viewpoint.

  Examples of the resin constituting the organic filler include polyamide, polyester, polyether, polysulfide, polyolefin, fluororesin, and polyvinyl alcohol. Specifically, polyamides such as nylon 46 (PA46), nylon 6 (PA6), nylon 66T (PA66T), nylon 610 (PA610), nylon 66 (PA66), nylon 6T (PA6T), PA · MXD6, and polyethylene terephthalate (PET), polyisobutylene terephthalate (PBT), polyethylene naphthalate (PEN), liquid crystal polymer (LCP), polyesters such as wholly aromatic arylate (PAR), polyether nitrile (PENT), polyether ether ketone (PENT), etc. Polyethers, polysulfides such as polyphenylene sulfide (PPS), polystyrenes such as syndiotactic polystyrene (SPS), aromatic polyethers such as polyphenylene oxide (PPO), poly Polyolefins such as lopyrene (PP) and poly-4-methyl-1-pentene (PMP), fluororesins such as tetrafluoroethylene / perfluoroalkoxyethylene resin (PFA) and polytetrafluoroethylene (PTFE), polyvinyl alcohol ( EVOH) and the like.

As the inorganic filler, Al ₂ O ₃ (aluminum oxide), ZnO (zinc oxide), SiO ₂ (silicon oxide), ZrO ₂ (zirconium oxide), TiO ₂ (titanium oxide), SiC (silicon carbide), MgO (magnesium oxide) ), CaO (calcium oxide), zeolite, AlN (aluminum nitride), BN (boron nitride) SnO ₂ (tin oxide), antimony oxide (Sb ₂ O ₅ ), ferrites, complex oxides thereof, calcium hydroxide, Aluminum hydroxide, zirconium hydroxide, magnesium hydroxide, carbon black, clay, calcium carbonate, barium carbonate, dosonite, hydrotalcite, calcium sulfate, magnesium carbonate, calcium silicate, potassium titanate, barium titanate, mica, montmorillonite and T Examples thereof include inorganic particles such as luc.
Among these inorganic fillers, Al ₂ O ₃ (aluminum oxide), SiO ₂ (silicon oxide), ZrO ₂ (zirconium oxide), TiO ₂ (titanium oxide), SiC (silicon carbide), MgO (magnesium oxide), zeolite It is preferable to include at least one inorganic particle selected from the group consisting of AlN (aluminum nitride) and BN (boron nitride). Al ₂ O ₃ (aluminum oxide), SiO ₂ (silicon oxide), ZrO ₂ (oxidation) More preferably, it contains at least one inorganic particle selected from the group consisting of zirconium), TiO ₂ (titanium oxide) and zeolite, and more preferably contains at least SiO ₂ (silicon oxide).

Among SiO ₂ , fumed silica is preferably used. When fumed silica is used, a function as a thickener or a thixotropy imparting material for a passivation film forming material can also be imparted. Furthermore, the moisture content of a passivation film can be improved by using hydrophilic fumed silica among fumed silica. Since these metal oxides have many hydroxyl groups on the surface, they easily interact with water and have high moisture retention. Therefore, the moisture retention of the passivation film can be further improved by adding these as inorganic fillers.

In particular, in a silicon solar cell, when the passivation film is formed on the back surface opposite to the light receiving surface using the semiconductor substrate passivation film forming material, the reflectance can be improved by including a filler. In that case, it is preferable to use SiO ₂ as the filler.

The filler may have a desired composition at the time when the semiconductor substrate passivation film is formed. For example, when an inorganic filler is used as a filler, the inorganic filler precursor is converted into an inorganic filler in a process of applying a coating material by drying a semiconductor substrate passivation film containing an inorganic filler precursor, a specific resin and a dispersion medium. It may change.
For example, by adding silane alkoxide, which is a precursor of SiO _{2, to} a passivation film forming material for a semiconductor substrate, it is hydrolyzed to SiO ₂ in a drying step. At this time, acid or alkali may be added as a catalyst.

  The average secondary particle diameter of the filler is not particularly limited. Among them, the weight average particle diameter (50% D) is preferably 10 nm to 30 μm, and more preferably 0.1 μm to 10 μm. When the weight average particle size of the filler is 10 nm or more, more uniform dispersion is possible in the material for forming a passivation film for a semiconductor substrate. Moreover, when it is 30 μm or less, the mechanical strength, moisture retention, reflectance, and heat resistance tend to be sufficiently improved. Here, the weight average particle diameter of the filler can be measured by a laser scattering diffraction particle size distribution measuring device or the like.

  When the material for forming a passivation film for a semiconductor substrate further contains a filler, the content of the filler is not particularly limited. For example, it is preferable that 0.1 mass%-200 mass% filler is included with respect to the specific resin contained in the passivation-film formation material for semiconductor substrates. The effect which added the filler is fully acquired as it is 0.1 mass% or more. Moreover, it can suppress that the softness | flexibility of a passivation film falls that it is 200 mass% or less, and can suppress that a pinhole etc. produce | generate.

[Dispersion medium]
The material for forming a passivation film for a semiconductor substrate of the present invention preferably further contains a dispersion medium in addition to the specific resin. The specific resin may be dissolved in a dispersion medium, or may be dispersed in a solid state or an emulsion state.
Examples of the dispersion medium include halogenated aliphatic hydrocarbon solvents such as water, chloroform, dichloromethane, 1,2-dichloroethane, trichloroethane, tetrachloroethane, trichloroethylene, and tetrachloroethylene; halogenated aromatic hydrocarbons such as dichlorobenzene and trichlorobenzene. Nitrogen compounds such as nitromethane and nitrobenzene; alkylbenzenes such as trimethylbenzene, tributylbenzene, tetramethylbenzene, and pentamethylbenzene; heterocyclic compounds such as sulfolane; straight chain such as octane, decane and cyclohexane Branched or cyclic aliphatic saturated hydrocarbon solvents; N, N-dimethylacetamide, N, N-dimethylformamide, dimethyl sulfoxide, N-methyl-2-pyrrolidone, hexamethylphosphona Suitable solvents can be selected from aprotic polar solvents such as methanol; alcohol solvents such as methanol, ethanol, 1-propanol and 2-propanol; phenol solvents such as phenol and cresol; It is not something.
Among these, it is preferable to include at least an alcohol solvent, and it is more preferable to include at least one selected from the group consisting of methanol, ethanol, 1-propanol and 2-propanol. By including at least one alcohol solvent, wettability to a semiconductor substrate, particularly a silicon substrate, can be improved.

  When the material for forming a passivation film for semiconductor substrate contains a dispersion medium, the content of the dispersion medium in the material for forming a passivation film for semiconductor substrate is not particularly limited. For example, it is preferably 1 part by mass to 99 parts by mass and more preferably 40 parts by mass to 95 parts by mass in 100 parts by mass of the total amount of the material for forming a passivation film for a semiconductor substrate.

[Ionic liquid]
The semiconductor substrate passivation film forming material may contain an ionic liquid. Such a material can be used by mixing any compatible polymer compound and ionic liquid. An ionic liquid is a salt having a melting point of 100 ° C. or lower and a liquid appearance at a low temperature of 100 ° C. or lower.

There is no restriction | limiting in particular in the composition of the said ionic liquid, If it is a composition dispersible in specific resin, it can use suitably. For example, examples of the cation include ammonium, pyridinium, pyrrolidinium, pyrrolium, oxazolium, oxazolinium, imidazolium, phosphonium, and sulfonium. Examples of the anionic ^{_{N (SO 2 F) 2 -}} , N (SO 2 CF 3) 2 -, N (SO 2 C 2 F 5) 2 -, BF 4 -, PF 6 -, CF 3 SO 3 - and CF ₃ CO ₂ ^- and the like. As the material for forming a passivation film for a semiconductor substrate, an ionic liquid combining these cations and anions can be used. The said ionic liquid may be used independently and can also be used in mixture of 2 or more types.

Among these anions, particularly hydrophobic anions N (SO ₂ F) ₂ ⁻ , N (SO ₂ CF ₃ ) ₂ ⁻ , N (SO ₂ C ₂ F ₅ ) ₂ ⁻ , CF ₃ SO ₃ ⁻ , Alternatively, CF ₃ CO ₂ ^— is preferably used. By using a hydrophobic anion, it becomes easy to handle an ionic liquid constituted by the hydrophobic anion, particularly in an air atmosphere, and the handling property of a passivation film forming material for a semiconductor substrate using the ionic liquid is improved. It becomes easy.

  The ionic conductivity of the ionic liquid is preferably 0.01 mS / cm or more, more preferably 0.1 mS / cm or more. The effect by having mixed the ionic liquid with specific resin as it is 0.01 mS / cm or more is fully acquired. In addition, the ionic conductivity of an ionic liquid is measured at 25 degreeC using an electric conductivity meter.

  Further, the cation or anion of the ionic liquid may be chemically bonded to the side chain of the specific resin.

[Silane coupling agent]
The semiconductor substrate passivation film forming material may further contain a silane coupling agent. By including the silane coupling agent, wettability to a semiconductor substrate, particularly a silicon substrate can be improved. It does not restrict | limit especially as a silane coupling agent, It can select suitably from the silane coupling agent used normally.

[Antistatic polymer]
The semiconductor substrate passivation film forming material may further include an antistatic polymer. The antistatic polymer here refers to a polymer in which an antistatic agent is kneaded and a polymer itself exhibiting antistatic properties. A surfactant is preferably used as the antistatic agent. A proton conductive polymer and an antistatic polymer may be mixed and used.

The semiconductor substrate passivation film forming material may contain a surfactant.
The surfactant may be any of cationic, anionic and nonionic. In some cases, a fixed charge can be more effectively imparted to the passivation film by including a surfactant.

<Method for manufacturing passivation film for semiconductor substrate>
In the method for producing a passivation film for a semiconductor substrate according to the present invention, a coating layer is formed by applying the passivation film forming material for a semiconductor substrate containing a polymer compound having an anionic group or a cationic group on the semiconductor substrate. It has a process and the process of drying the said application layer and forming a coating film, and is comprised including another process as needed. By using the semiconductor substrate passivation film forming material, a semiconductor substrate passivation film having an excellent surface passivation effect can be formed.

  The method for manufacturing a passivation film for a semiconductor substrate preferably further includes a step of applying a hydrofluoric acid aqueous solution on the semiconductor substrate before the step of forming the coating layer, and before the step of applying the hydrofluoric acid aqueous solution. It is more preferable to further include a step of applying an alkaline aqueous solution. That is, it is preferable to clean the surface of the semiconductor substrate with a hydrofluoric acid aqueous solution before applying the semiconductor substrate passivation film forming material on the semiconductor substrate, and further, after cleaning the surface of the semiconductor substrate with an alkaline aqueous solution, It is more preferable to wash with an acid aqueous solution. By washing with a hydrofluoric acid aqueous solution, silicon oxide present on the surface of the semiconductor substrate can be removed, and the passivation effect is further improved. In addition, dangling bonds existing in the semiconductor substrate can be changed to Si-H bonds. By applying the material for forming a passivation film for a semiconductor substrate to this, there is a possibility that the formed Si—H bond can be stabilized. Details of the step of applying the hydrofluoric acid aqueous solution and the step of applying the alkaline aqueous solution will be described later.

In a first aspect of the method for producing a passivation film for a semiconductor substrate, a material for forming a passivation film for a semiconductor substrate containing a polymer compound having an anionic group is applied on a p-type layer of the semiconductor substrate. And a step of drying the coating layer to form a coating film, and including other steps as necessary.
By using the semiconductor substrate passivation film forming material, a semiconductor substrate passivation film having an excellent surface passivation effect can be formed.

The p-type layer on the semiconductor substrate may be either a p-type layer derived from the p-type semiconductor substrate, or a p-type diffusion layer or a p ⁺ -type diffusion layer formed on the semiconductor substrate. .

In the present invention, it is preferable to further include a step of applying a hydrofluoric acid aqueous solution on the p-type layer of the semiconductor substrate before the step of forming the coating layer, and an alkaline aqueous solution is added before the step of applying the hydrofluoric acid aqueous solution. It is more preferable to further include a step of imparting.
That is, the surface of the p-type layer is preferably washed with a hydrofluoric acid aqueous solution before applying the semiconductor substrate passivation film forming material on the p-type layer of the semiconductor substrate, and the surface of the p-type layer is further washed with an alkaline aqueous solution. It is more preferable to wash with an aqueous hydrofluoric acid solution after washing with.

By washing with a hydrofluoric acid aqueous solution, silicon oxide present on the surface of the semiconductor substrate can be removed, and the passivation effect is further improved.
In addition, dangling bonds existing in the semiconductor substrate can be changed to Si-H bonds. By applying the material for forming a passivation film for a semiconductor substrate to this, there is a possibility that the formed Si—H bond can be stabilized.

Examples of the cleaning method using an alkaline aqueous solution include generally known RCA cleaning. For example, the organic substance and particles can be removed and washed by immersing the semiconductor substrate in a mixed solution of aqueous ammonia and hydrogen peroxide and treating the substrate at 60 ° C. to 80 ° C.
Although there is no restriction | limiting in particular as a density | concentration of the hydrofluoric acid of hydrofluoric acid aqueous solution, 0.1 mass%-40 mass% aqueous solution can be used, and it is preferable that it is 0.5 mass%-10 mass%. There exists a tendency for sufficient cleaning effect to be acquired as it is 0.1 mass% or more. Moreover, it can suppress that the handleability of a washing process falls that it is 40 mass% or less.
The cleaning time is preferably 10 seconds to 10 minutes, more preferably 30 seconds to 5 minutes, in both alkali cleaning and hydrofluoric acid cleaning.

The second aspect of the method for producing a passivation film for a semiconductor substrate is a coating layer obtained by applying the passivation film forming material for a semiconductor substrate containing a polymer compound having a cationic group onto an n-type layer of the semiconductor substrate. And a step of drying the coating layer to form a coating film, and including other steps as necessary.
By using the semiconductor substrate passivation film forming material, a semiconductor substrate passivation film having an excellent surface passivation effect can be formed.

The n-type layer on the semiconductor substrate may be either an n-type layer derived from the n-type semiconductor substrate, or an n-type diffusion layer or an n ⁺ -type diffusion layer formed on the semiconductor substrate. .

In the present invention, it is preferable to further include a step of applying a hydrofluoric acid aqueous solution on the n-type layer of the semiconductor substrate before the step of forming the coating layer, and an alkaline aqueous solution is added before the step of applying the hydrofluoric acid aqueous solution. It is more preferable to further include a step of imparting.
That is, the surface of the n-type layer is preferably washed with a hydrofluoric acid aqueous solution before applying the semiconductor substrate passivation film forming material onto the n-type layer of the semiconductor substrate, and the surface of the n-type layer is preferably washed with an alkaline aqueous solution. It is more preferable to wash with an aqueous hydrofluoric acid solution after washing with.

  Cleaning of the n-type layer surface with a hydrofluoric acid aqueous solution and cleaning with an alkaline aqueous solution are the same as the cleaning of the p-type layer surface with a hydrofluoric acid aqueous solution and cleaning with an alkaline aqueous solution.

  In the method for manufacturing a passivation film for a semiconductor substrate, there is no particular limitation on a method for forming a coating layer by applying a material for forming a passivation film for a semiconductor substrate on a semiconductor substrate, and a known coating method may be used. it can. Specific examples include immersion method, printing method, spin method, brush coating, spray method, doctor blade method, roll coater method, and ink jet method.

  The coating amount of the semiconductor substrate passivation film forming material can be appropriately selected according to the purpose. For example, the thickness of the formed passivation film for a semiconductor substrate can be set to 10 nm to 50 μm.

  The passivation layer for a semiconductor substrate can be formed on the semiconductor substrate by drying the coating layer formed of the passivation film forming material for the semiconductor substrate to form a coating film. The drying conditions for the coating layer are not particularly limited as long as a coating film can be formed. For example, it is preferable to dry at 50 to 300 ° C.

  The thickness of the passivation film for a semiconductor substrate manufactured by the method for manufacturing a passivation film for a semiconductor substrate is not particularly limited and can be appropriately selected according to the purpose. For example, the thickness is preferably 10 nm to 50 μm, preferably 100 nm to 30 μm, and more preferably 500 nm to 20 μm. When it is 10 nm or more, it tends to be easy to uniformly cover the entire desired region of the semiconductor substrate surface. Also, the thicker the film, the higher the surface passivation effect.

  The film thickness of the formed semiconductor substrate passivation film is measured by a conventional method using a stylus type step / surface shape measuring device (for example, manufactured by Ambios).

In the above description, the method for producing a semiconductor substrate passivation film by applying a liquid semiconductor substrate passivation film forming material to the surface of the semiconductor substrate has been described. By using this, a passivation film for a semiconductor substrate can be manufactured.
Specifically, a method for producing a passivation film for a semiconductor substrate includes a material for forming a passivation film for a semiconductor substrate that includes a polymer compound having an anionic group on a p-type layer of the semiconductor substrate and is formed into a film shape. You may have a process to stick.
Furthermore, it is preferable to wash the p-type layer on the semiconductor substrate with an aqueous hydrofluoric acid solution before attaching the film-forming material for forming a passivation film for a semiconductor substrate.

Furthermore, a method for manufacturing a passivation film for a semiconductor substrate includes a step of attaching a film forming material for forming a passivation film for a semiconductor substrate containing a polymer compound having a cationic group on an n-type layer of the semiconductor substrate. It may have.
Furthermore, it is preferable to wash the n-type layer on the semiconductor substrate with a hydrofluoric acid aqueous solution before attaching the film-forming material for forming a passivation film for a semiconductor substrate.

In the present invention, the specific resin contained in the passivation film obtained by applying and drying the passivation film forming material for the semiconductor substrate on the semiconductor substrate and drying may be subjected to a crosslinking treatment. Good. By performing the crosslinking treatment, the heat resistance can be further improved.
The method for the crosslinking treatment is not particularly limited, and can be appropriately selected from commonly used crosslinking methods.

<Solar cell element and manufacturing method thereof>
The solar cell element of this invention has the semiconductor substrate which has pn junction, an electrode, and the said passivation film for semiconductor substrates provided on the said semiconductor substrate. The solar cell element may further include other components as necessary.

  The method for manufacturing a solar cell element of the present invention includes a step of forming the semiconductor substrate passivation film on a semiconductor substrate having a pn junction and provided with electrodes. The method for manufacturing a solar cell element may further include other steps as necessary.

Next, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a cross-sectional view schematically illustrating a process diagram schematically showing an example of a method for producing a solar cell element having a semiconductor substrate passivation film according to the present embodiment. However, this process diagram does not limit the usage method of the present invention.

As shown in FIG. 1A, in a p-type semiconductor substrate 1, an n ⁺ -type diffusion layer 2 is formed in the vicinity of the surface, and an antireflection film 3 is formed on the surface. As the antireflection film 3, a silicon nitride film, a titanium oxide film, or the like is known. A surface protective film (not shown) such as silicon oxide may exist between the antireflection film 3 and the p-type semiconductor substrate 1. Further, the passivation film of the present invention may be used as a surface protective film.

Next, as shown in FIG. 1B, a material for forming the back electrode 5 such as an aluminum electrode paste is applied to a partial region of the back surface, and then heat-treated to form the back electrode 5 and diffuse aluminum. A p ⁺ -type diffusion layer 4 is formed.

Next, as shown in FIG. 1C, the electrode 7 is applied to the light-receiving surface side and then heat-treated to form the surface electrode 7. By using 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 surface electrode 7 can be formed to obtain an ohmic contact.

  Finally, as shown in FIG. 1D, a passivation film forming material for a semiconductor substrate containing a polymer compound having an anionic group is applied on the p-type layer on the back surface other than the back electrode 5 by screen printing or the like. The passivation film 6 is formed by applying and drying by the method. By forming the back surface passivation film 6 on the p-type layer, a solar cell element excellent in power generation efficiency can be manufactured.

  In the solar cell element manufactured by the manufacturing method including the manufacturing process shown in FIG. 1, the back electrode made of aluminum or the like can have a point contact structure, and the warpage of the substrate can be reduced.

Further, FIG. 1D shows a method of forming a passivation film only on the back surface portion, but in addition to the back surface side of the semiconductor substrate 1, a semiconductor substrate passivation film forming material is applied to the side surface and dried. A passivation film may be further formed on the side surface (edge) of the semiconductor substrate 1 (not shown). Thereby, the solar cell element excellent in power generation efficiency can be manufactured.
Furthermore, the passivation film may be formed by applying and drying the passivation film forming material for a semiconductor substrate of the present invention only on the side surface without forming the passivation film on the back surface portion. The material for forming a passivation film for a semiconductor substrate of the present invention is particularly effective when used in a place where there are many crystal defects such as side surfaces.

  Although the embodiment of forming the passivation film after forming the electrode has been described with reference to FIG. 1, after forming the passivation film, an electrode such as aluminum may be further formed on the entire surface by vapor deposition or the like. It may be formed on the front surface.

FIG. 2 is a cross-sectional view illustrating a process diagram schematically showing another example of a method for manufacturing a solar cell element having a semiconductor substrate passivation film according to the present embodiment. Specifically, 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. Here, the p-type diffusion layer forming composition can be configured to include, for example, an acceptor element-containing material and a glass component.

As shown in FIG. 2A, 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. As the antireflection film 3, a silicon nitride film, a titanium oxide film, or the like is known.

Next, as shown in FIG. 2B, 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. On the p ⁺ type diffusion layer 4, a heat treatment product 8 of a composition for forming a p ⁺ type diffusion layer is formed.
Here, instead of the p-type diffusion layer forming composition, an aluminum electrode paste may be used. When the aluminum electrode paste is used, an aluminum electrode is formed as the heat treatment 8 on the p ⁺ type diffusion layer 4.

Next, as shown in FIG. 2C, the heat-treated product 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.

Next, as shown in FIG. 2 (d), the electrode forming paste is selectively applied to a part of the light receiving surface (front surface) and the back surface, and then heat-treated to form the surface electrode 7 on the light receiving surface (front surface). A back electrode 5 is formed on the back surface. By using a paste containing a glass powder having fire-through property as an electrode forming paste applied to the light receiving surface side, the n ⁺ type diffusion layer 2 penetrates the antireflection film 3 as shown in FIG. A surface electrode 7 is formed on the surface to obtain an ohmic contact.
Further, since the p ⁺ -type diffusion layer 4 is already formed in the region where the back electrode is formed, 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 paste capable of forming a lower resistance electrode can also be used. As a result, the power generation efficiency can be further increased.

  Finally, as shown in FIG. 2 (e), a passivation film forming material for a semiconductor substrate containing a polymer compound having an anionic group is applied on the p-type layer on the back surface other than the back electrode 5 and dried for passivation. A film 6 is formed. By forming the back surface passivation film 6 on the p-type layer, a solar cell element excellent in power generation efficiency can be manufactured.

Further, FIG. 2E shows a method of forming a passivation film only on the back surface portion, but in addition to the back surface side of the p-type semiconductor substrate 1, a semiconductor substrate passivation film forming material is applied to the side surface and dried. Thus, a passivation film may be further formed on the side surface (edge) of the p-type semiconductor substrate 1 (not shown). Thereby, the solar cell element excellent in power generation efficiency can be manufactured.
Furthermore, the passivation film may be formed by applying and drying the passivation film forming material for a semiconductor substrate of the present invention only on the side surface without forming the passivation film on the back surface portion. The material for forming a passivation film for a semiconductor substrate of the present invention is particularly effective when used in a place where there are many crystal defects such as side surfaces.

  In FIG. 2, the embodiment in which the passivation film is formed after the electrode formation is described. However, after the passivation film is formed, an electrode such as aluminum may be further formed on the entire surface by vapor deposition or the like, and an electrode that does not need to be fired at a high temperature is formed. It may be formed on the front surface.

In the embodiment described above, the case where a p-type semiconductor substrate having an n ⁺ -type diffusion layer formed on the light-receiving surface has been described. 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 side.

Furthermore, the passivation film forming material for a semiconductor substrate can also be used to form a passivation film 6 on the light receiving surface side or the back surface side of a back electrode type solar cell element in which an electrode is disposed only on the back surface side as shown in FIG. .
As shown in a schematic cross-sectional view in FIG. 3, an n ⁺ -type diffusion layer 2 is formed near the surface on the light-receiving surface side of the p-type semiconductor substrate 1, and a passivation film 6 and an antireflection film 3 are formed on the surface. ing. As the antireflection film 3, a silicon nitride film, a titanium oxide film, or the like is known. The passivation film 6 is formed by applying and drying the material for forming a passivation film for a semiconductor substrate of the present invention.

On the back side of the p-type semiconductor substrate 1, a back electrode 5 is provided on each of the p ⁺ -type diffusion layer 4 and the n ⁺ -type diffusion layer 2, and a passivation film 6 is formed in a region where no back-side electrode is formed. Is provided.
The p ⁺ -type diffusion layer 4 can be formed by applying a heat treatment after applying the p-type diffusion layer forming composition or the aluminum electrode paste to a desired region as described above. Further, the n ⁺ -type diffusion layer 2 can be formed, for example, by 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. Here, the composition for forming an n-type diffusion layer can be configured to include, for example, a donor element-containing material and a glass component.

The back electrode 5 provided on each of the p ⁺ type diffusion layer 4 and the n ⁺ type diffusion layer 2 can be formed using a commonly used electrode forming paste such as a silver electrode paste.
The back electrode 5 provided on the p ⁺ -type diffusion layer 4 may be an aluminum electrode formed with the p ⁺ -type diffusion layer 4 using an aluminum electrode paste.
The passivation film 6 provided on the back surface can be formed by applying a semiconductor substrate passivation film forming material to a region where the back electrode 5 is not provided and drying.
The passivation film 6 may be formed not only on the back surface of the semiconductor substrate 1 but also on the side surfaces (not shown).

  In the back electrode type solar cell element as shown in FIG. 3, since there is no electrode on the light receiving surface side, power generation efficiency is excellent. Further, since the passivation film is formed in the region where the back electrode is not formed, the power generation efficiency is further improved.

  EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples. Unless otherwise stated, all chemicals used reagents. Unless otherwise specified, “%” is based on mass.

<Example 1>
(Application of passivation film forming material)
As the semiconductor substrate, a single crystal p-type silicon substrate (manufactured by SUMCO, 25 mm square, thickness: 625 μm) having a mirror shape was used. The silicon substrate was washed with an RCA cleaning solution (Frontier Cleaner-A01 manufactured by Kanto Chemical Co., Ltd.) for 5 minutes at 70 ° C. and then immersed in a 2.5 mass% hydrofluoric acid aqueous solution for 5 minutes at room temperature. Subsequently, it was washed with water, then with ethanol, and then air-dried.
Thereafter, as a material for forming a passivation film for a semiconductor substrate, a 5% dispersion of Nafion resin (1-propanol / 2-propanol = 45/55 (mass ratio), water: 15% by mass to 20% by mass, manufactured by Aldrich) Was applied to one side of a silicon substrate using a spin coater. Spin coating was performed at 2000 rpm for 30 seconds, and then dried on a hot plate at 90 ° C. for 10 minutes, and then allowed to cool at room temperature.

(Measurement of conductivity of specific resin)
Using a Nafion membrane (manufactured by Aldrich), a platinum plate (width: 10 mm) was pressed against the surface of a strip-like membrane sample made of Nafion membrane on a self-made measurement probe (manufactured by Teflon (registered trademark)), and 25 ° C. In water, the impedance between platinum plates was measured by 1260 FREQUENCY RESPONSE ANALYSER manufactured by SOLARTRON.
When measuring, change the distance between the poles, and cancel the contact resistance between the membrane and the platinum wire using the following formula from the gradient plotting the distance measured between the poles and the resistance measurement value estimated from the CC plot. The calculated conductivity was calculated as the conductivity of the specific resin.
Formula for calculating conductivity:
Conductivity [mS / cm] = 1 / (film width [cm] × film thickness [cm] × resistance interelectrode gradient [Ω · cm ⁻¹ ]) × 100
The conductivity of Nafion resin was 11 mS / cm.

(Measurement of effective lifetime)
The lifetime of the silicon substrate on which the passivation film forming material for the semiconductor substrate containing Nafion resin is applied and the passivation film is formed is reflected using a lifetime measurement apparatus (WT-2000PVN, manufactured by Nippon Semi-Lab). As a result, the effective lifetime was 110 μs. The measurement was performed at 25 ° C.

(Measurement of passivation film thickness)
The thickness of the passivation film formed on the silicon substrate was measured using a stylus type step / surface shape measuring device (Ambios). The thickness of the passivation film was 0.32 μm. The results are shown in Table 1.

<Example 2>
In Example 1, a passivation film was formed on a silicon substrate in the same manner as in Example 1 except that cleaning with an aqueous hydrofluoric acid solution was not performed, and evaluation was performed in the same manner.
The effective lifetime was 50 μs. The thickness of the passivation film was 0.31 μm.

<Example 3>
The silicon substrate is immersed in a 5% dispersion of Nafion resin (1-propanol / 2-propanol = 45/55 (mass ratio), water: 15% to 20% by mass, manufactured by Aldrich), and then air-dried. The film was dried at 90 ° C. for 10 minutes and then allowed to cool at room temperature to form a passivation film on the silicon substrate.
Evaluation was performed in the same manner as in Example 1 using the obtained silicon substrate on which the passivation film was formed.
The effective lifetime was 250 μs. The thickness of the passivation film was 0.90 μm.

<Example 4>
In Example 1, instead of 5% Nafion resin dispersion, 5% solution of sulfonated styrene-olefin copolymer resin (sulfonated Polystyrene-block-poly (ethylene-ran-butylene) block-polystyrene, 1-propanol) A dichloroethane dispersion (manufactured by Aldrich) was used to form a passivation film on the silicon substrate in the same manner as in Example 1. Evaluation was performed in the same manner as in Example 1 using the obtained silicon substrate on which the passivation film was formed.
The effective lifetime was 90 μs. The thickness of the passivation film was 0.56 μm.
When the sulfonated styrene-olefin copolymer resin was molded into a film and the conductivity was measured in the same manner as in Example 1, it was 10 mS / cm.

<Example 5>
In Example 3, instead of 5% Nafion resin dispersion, 5% dispersion of sulfonated styrene-olefin copolymer resin (sulfonated Polystyrene-block-poly (ethylene-ran-butylene) block-polystyrene, 1-propanol) A dichloroethane dispersion (manufactured by Aldrich) was used to form a passivation film on the silicon substrate in the same manner as in Example 3. Evaluation was performed in the same manner as in Example 1 using the obtained silicon substrate on which the passivation film was formed.
The effective lifetime was 210 μs. The thickness of the passivation film was 1.10 μm.

<Example 6>
(Synthesis Example 1)
(Synthesis of sulfonated polyarylethersulfone)
Each reagent used in the synthesis was vacuum dried at 105 ° C. for 4 hours, and then placed in a 500 ml separable flask with 20.0 g (39.3 mmol) of bis (4-chloro-3-sulfophenyl) sulfonic acid sodium salt, 4, 11.3 g (39.3 mmol) of 4′-dichlorodiphenylsulfone, 15.9 g (78.5 mmol) of 4,4′-dihydroxydiphenyl ether and 13.0 g (94.3 mmol) of potassium carbonate were added, and the same conditions as described above were added. And vacuum drying for 1 hour. Thereafter, the system was quickly purged with nitrogen, and under a nitrogen stream, 200 ml of NMP (N-methylpyrrolidone) and 150 ml of toluene were added and stirred at room temperature for 30 minutes. Thereafter, the reaction temperature was set to 160 ° C., the generated water was azeotroped with toluene, and water was taken out of the system.
Thereafter, the reaction temperature was set to 180 ° C., and the reaction was further continued for 50 hours. The reaction mixture was added to 5% aqueous hydrochloric acid and reprecipitated to precipitate the polymer. The precipitated polymer was washed with purified water and collected by suction filtration using filter paper. This was dried in a dryer at 110 ° C. for 8 hours to obtain a sulfonated polyarylethersulfone as a specific resin.

Using 0.60 g of the specific resin synthesized in Synthesis Example 1, a 10% NMP solution of the specific resin was prepared. This was cast on glass and dried to obtain a film. The membrane was then immersed in a 20% aqueous sulfuric acid solution and stirred for 1 hour. Then, it washed with water 3 times and obtained the specific resin film.
When the electrical conductivity of the obtained specific resin film was measured in the same manner as described above, it was 10 mS / cm.

The specific resin obtained above was dissolved in methanol (dispersion medium) to obtain a 10% methanol solution. A passivation film was formed on the silicon substrate by applying and drying on the silicon substrate in the same manner as in Example 1 except that this solution was used. Evaluation was performed in the same manner as in Example 1 using the obtained silicon substrate on which the passivation film was formed.
The effective lifetime was 90 μs. The thickness of the passivation film was 0.45 μm.

<Example 7>
A passivation film was formed on the silicon substrate in the same manner as in Example 6 except that NMP was used instead of methanol as the dispersion medium. Evaluation was performed in the same manner as in Example 1 using the obtained silicon substrate on which the passivation film was formed.
The effective lifetime was 45 μs. The thickness of the passivation film was 0.52 μm.

<Example 8>
A 25% poly (styrene sulfonic acid) aqueous solution (manufactured by Aldrich) was evaporated to dryness, and the residue was dissolved in methanol to prepare a 25% poly (styrene sulfonic acid) methanol solution.
In Example 1, a passivation film was formed on the silicon substrate in the same manner as in Example 1 except that a 25% poly (styrenesulfonic acid) methanol solution was used instead of the 5% Nafion resin dispersion. Evaluation was performed in the same manner as in Example 1 using the obtained silicon substrate on which the passivation film was formed.
The effective lifetime was 90 μs. The thickness of the passivation film was 0.35 μm.
Poly (styrene sulfonic acid) was molded into a film shape, and the conductivity was measured in the same manner as in Example 1. The result was 10 mS / cm.

<Example 9>
(Preparation of passivation film forming material for semiconductor substrate)
5 mass% Nafion resin dispersion (1-propanol / 2-propanol = 45/55 (mass ratio), water: 15 mass% to 20 mass%, manufactured by Aldrich) and SiO ₂ particles (manufactured by High Purity Chemical Laboratory) , Weight average particle diameter (50% D) 1 μm, purity 99.9%) was added and ultrasonically dispersed to prepare a SiO ₂ -containing Nafion resin dispersion as a material for forming a passivation film for a semiconductor substrate. In this case, the content of SiO ₂ is prepared as a 1% by weight, based on the Nafion resin.

(Formation of passivation film)
As the semiconductor substrate, a single crystal p-type silicon substrate (manufactured by SUMCO, 25 mm square, thickness: 625 μm) having a mirror-shaped surface was used. The silicon substrate was washed with RCA cleaning solution (Frontier Cleaner-A01 manufactured by Kanto Chemical Co., Ltd.) at 70 ° C. for 5 minutes, and then immersed in a 2.5 mass% hydrofluoric acid aqueous solution at room temperature for 5 minutes. Subsequently, it was washed with water, then with ethanol, and then air-dried.
Thereafter, the silicon substrate was dipped (immersed) in the SiO ₂ -containing Nafion dispersion obtained above and then pulled up, then dried on a hot plate at 90 ° C. for 10 minutes, and then allowed to cool at room temperature to form a passivation film. Each formed silicon substrate was obtained.

(Measurement of effective lifetime)
The lifetime of the silicon substrate on which the passivation film, which is a composite film composed of SiO ₂ and Nafion obtained as described above, is measured at 25 ° C. using a lifetime measuring device (WT-2000PVN manufactured by Nippon Semi-Lab) and reflected microwave photoelectric conduction The results measured by the attenuation method are shown in Table 1.

(Measurement of passivation film thickness)
The thickness of the passivation film was 1.3 μm.

<Example 10>
In Example 9, a passivation film was formed on a silicon substrate in the same manner as in Example 9 except that the content of SiO ₂ was 5% by mass with respect to the Nafion resin, and evaluation was performed in the same manner. .
The thickness of the passivation film was 1.3 μm.

<Example 11>
In Example 9, a passivation film was formed on a silicon substrate in the same manner as in Example 9 except that the content of SiO ₂ was 10% by mass with respect to the Nafion resin, and evaluation was performed in the same manner. .
The thickness of the passivation film was 1.4 μm.

<Example 12>
In Example 9, a passivation film was formed on a silicon substrate in the same manner as in Example 9 except that the content of SiO ₂ was 20% by mass with respect to the Nafion resin, and evaluation was performed in the same manner. .
The thickness of the passivation film was 1.4 μm.

<Example 13>
In Example 9, a passivation film was formed on a silicon substrate in the same manner as in Example 9 except that the content of SiO ₂ was 50% by mass with respect to the Nafion resin, and evaluation was performed in the same manner. .
The thickness of the passivation film was 1.5 μm.

<Example 14>
In Example 9, a passivation film was formed on a silicon substrate in the same manner as in Example 9 except that the content of SiO ₂ was 100% by mass with respect to the Nafion resin, and evaluation was performed in the same manner. .
The thickness of the passivation film was 1.5 μm.

<Example 15>
In Example 9, instead of 5% Nafion resin dispersion, a 5% solution of sulfonated styrene-olefin copolymer resin (sulfonated Polystyrene-block-poly (ethylene-ran-butylene) block-polystyrene, 1-propanol) A dichloroethane solution (manufactured by Aldrich) was used, and a passivation film was formed on a silicon substrate in the same manner as in Example 9 and evaluated in the same manner.

<Example 16>
In Example 11, fumed silica (manufactured by Aerosil Japan, Aerosil 200, weight average particle diameter) instead of SiO ₂ particles (manufactured by High Purity Chemical Laboratory, weight average particle diameter (50% D) 1 μm, purity 99.9%). (50% D) A passivation film was formed on a silicon substrate in the same manner except that 0.3 μm and a BET specific surface area of 200 m 2 / g) were used, and evaluation was performed in the same manner. The thickness of the passivation film was 0.8 μm.

<Comparative Example 1>
In Example 1, the execution lifetime in the silicon substrate was measured in the same manner as in Example 1 except that the 5% Nafion resin dispersion was not applied.
The effective lifetime was 22 μs.

<Comparative example 2>
In Example 1, instead of the 5% Nafion resin dispersion, 10% polyvinyl alcohol (Wako Pure Chemical Industries, average molecular weight: 20,000, partially saponified type) aqueous solution was used in the same manner as in Example 1, A resin film was formed on the silicon substrate. Evaluation was performed in the same manner as in Example 1 by using the obtained silicon substrate on which the resin film was formed.
The effective lifetime was 23 μs. The resin film thickness was 0.35 μm.
Further, a 10% polyvinyl alcohol aqueous solution was cast on glass to prepare a polyvinyl alcohol film, and the above and the electrical conductivity were measured. The conductivity was below the measurement detection of 0.01 mS / cm or less.

<Comparative Example 3>
In Example 1, a 10% polyethylene oxide (manufactured by Wako Pure Chemical Industries, Ltd., average molecular weight: 20,000) ethanol solution was used in the same manner as in Example 1 except that a 5% Nafion resin dispersion was used. A resin film was formed. Evaluation was performed in the same manner as in Example 1 by using the obtained silicon substrate on which the resin film was formed.
The effective lifetime was 24 μs. The resin film thickness was 0.34 μm.
Further, an ethanol / water solution of 10% polyethylene oxide was cast on glass to prepare a polyethylene oxide film, and the conductivity was measured. The conductivity was below the measurement detection of 0.01 mS / cm or less.

<Comparative example 4>
In Example 3, a resin film was formed on a silicon substrate in the same manner as in Example 3 except that an ethanol solution of 10% polyethylene oxide was used instead of the 5% Nafion resin dispersion. Evaluation was performed in the same manner as in Example 1 by using the obtained silicon substrate on which the resin film was formed.
The effective lifetime was 23 μs. The resin film thickness was 0.32 μm.

<Comparative Example 5>
In Example 3, a resin film was formed on a silicon substrate in the same manner as in Example 3 except that a polyimide solution (PIX-1400 manufactured by Hitachi Chemical DuPont Microsystems) was used instead of the 5% Nafion resin dispersion. Evaluation was performed in the same manner as in Example 1 by using the obtained silicon substrate on which the resin film was formed.
The effective lifetime was 25 μs. The resin film thickness was 0.60 μm.
Furthermore, the polyimide solution was cast on glass to prepare a polyimide film, and the conductivity of the polyimide film in water at 25 ° C. was measured in the same manner as described above. The conductivity was below the measurement detection of 0.01 mS / cm or less.

  For Examples 3, 5, and 9 to 16, except that the drying temperature at the time of forming the passivation film was changed from 90 ° C. to 150 ° C., 200 ° C., and 250 ° C., respectively, and the drying was performed for 10 minutes. Similarly, silicon substrates on which passivation films having different drying temperatures were formed were produced. With respect to the obtained silicon substrate, the execution lifetime was evaluated in the same manner as described above, and the results are shown in Table 2.

  From Table 1, by applying and drying a passivation film forming material for a semiconductor substrate containing a specific resin on the surface of the semiconductor substrate to form a passivation film on the semiconductor substrate, the effect of minority carriers in and on the semiconductor substrate is improved. It was found that the lifetime was greatly improved and an excellent passivation effect was obtained. Moreover, it turned out that Examples 9-16 using a filler show favorable execution lifetime even if drying temperature is high temperature from Table 2.

1 p-type semiconductor substrate 2 n ⁺ -type diffusion layer 3 antireflection film 4 p ⁺ -type diffusion layer 5 back surface electrode 6 passivation film 7 surface electrode 8 p heat-treated product of ⁺ -type diffusion layer forming composition

Claims (17)

  A material for forming a passivation film for a semiconductor substrate, comprising a polymer compound having an anionic group or a cationic group.   2. The semiconductor substrate according to claim 1, wherein the polymer compound has a main chain composed of a carbon atom and at least one atom selected from the group consisting of a hydrogen atom, a fluorine atom, an oxygen atom, and a sulfur atom. Material for forming passivation film.   The material for forming a passivation film for a semiconductor substrate according to claim 1, wherein the polymer compound has an aromatic group.   The material for forming a passivation film for a semiconductor substrate according to any one of claims 1 to 3, wherein the conductivity of the polymer compound is 1 mS / cm or more in water at 25 ° C.   The said high molecular compound has at least 1 sort (s) of anionic group chosen from the group which consists of a sulfonic acid group, a carboxy group, a phosphoric acid group, a phosphonic acid group, and a phenolic hydroxyl group. The material for forming a passivation film for a semiconductor substrate according to the item.   The said high molecular compound is at least 1 sort (s) chosen from the group which consists of a polyperfluoro olefin sulfonic acid derivative, a sulfonated polystyrene derivative, and a sulfonated polyaryl ether sulfone. A material for forming a passivation film for a semiconductor substrate.   The material for forming a passivation film for a semiconductor substrate according to any one of claims 1 to 6, further comprising a filler.   The material for forming a passivation film for a semiconductor substrate according to claim 7, wherein the filler is an inorganic filler. 9. The semiconductor substrate according to claim 7, wherein the filler includes at least one selected from the group consisting of Al ₂ O ₃ , SiO ₂ , ZrO ₂ , TiO ₂ , SiC, MgO, zeolite, AlN, and BN. Material for forming passivation film.   The material for forming a passivation film for a semiconductor substrate according to any one of claims 7 to 9, wherein a weight average particle diameter (50% D) of the filler is 10 nm to 30 µm.   The material for forming a passivation film for a semiconductor substrate according to any one of claims 1 to 10, further comprising a dispersion medium.   The material for forming a passivation film for a semiconductor substrate according to claim 11, wherein the dispersion medium contains at least one selected from the group consisting of methanol, ethanol, 1-propanol, and 2-propanol.   A passivation film for a semiconductor substrate, which is provided on a semiconductor substrate and is a coating film of the material for forming a passivation film for a semiconductor substrate according to any one of claims 1 to 12.   A step of applying a passivation film forming material for a semiconductor substrate according to any one of claims 1 to 12 on a semiconductor substrate to form a coating layer, and drying the coating layer to form a coating film. Forming a passivation film for a semiconductor substrate.   The method for producing a passivation film for a semiconductor substrate according to claim 14, further comprising a step of applying a hydrofluoric acid aqueous solution on the semiconductor substrate before the step of forming the coating layer.   The solar cell element which has a semiconductor substrate which has a pn junction, an electrode, and the passivation film for semiconductor substrates of Claim 13 provided on the said semiconductor substrate.   The manufacturing method of the solar cell element which has the process of forming the passivation film for semiconductor substrates of Claim 13 on the semiconductor substrate which has a pn junction and was provided with the electrode.