JP2003171556A - Method for forming silicon film and composition therefor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for forming a semiconductor thin film easily and in an inexpensive way, the method not requiring expensive, energy-intensive, large-scale equipment, and being applicable to a large-area substrate, and to provide a silane composition therefor. <P>SOLUTION: A solar battery with a structure having, between a pair of electrodes, at least two laminated semiconductor thin film layers having different impurity concentrations and/or different kind of impurities, is manufactured by forming at least one of the semiconductor thin film layers according to the method comprising the steps of forming a coating film by applying onto the substrate a silane composition comprising (A) a polysilane compound represented by the formula: Si<SB>n</SB>R<SB>m</SB>, (B) at least one type of silane compound selected from the group consisting of cyclopentasilane, cyclohexasilane and silylcyclopentasilane, (C) silicon particles, and optionally, (D) a boron compound, an arsenic compound, a phosphorus compound, an antimony compound and a modified silane compound, and by thermally and/or optically processing the coating film. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a method for forming a silicon film and a silane composition therefor. More specifically, the present invention relates to a method for forming a silicon film applied to general electronic devices such as solar cells, LSIs, TFTs, and photoconductors, and a silane composition used therefor.

[0002]

2. Description of the Related Art Conventionally, as a method for forming an amorphous silicon film or a polysilicon film used for manufacturing a solar cell, thermal CVD (Che of a monosilane gas or a disilane gas is used.
The metallic vapor deposition method, plasma CVD, photo-CVD and the like are used. Generally, thermal CVD (J. Vac.
Sci. Technology. , Vol. 14, p. 1082 (1977)), and plasma CVD (Solid State) for forming an amorphous silicon film.
Com. , 17: 1193 (1975)) is widely used.

However, in the formation of a silicon film by the CVD method, since a gas phase reaction is used, by-production of silicon particles in the gas phase causes contamination of the device and generation of foreign matter, resulting in a low production yield and a gaseous raw material. Therefore, it is difficult to obtain a film having a uniform film thickness on a substrate having an uneven surface, or productivity is low due to a low film forming speed, and the plasma CVD method is complicated. There are problems such as the need for expensive high-frequency generators and vacuum devices, and further improvements have been awaited.

Further, in terms of materials, since gaseous silicon hydride which is highly toxic and reactive is used, it is difficult to handle, and since it is gaseous, a closed vacuum device is required. Is causing problems. That is, in general, these devices are large-scaled and not only expensive, but also a large amount of energy is consumed in the vacuum system and the plasma system, which leads to high product cost.

In recent years, there has been proposed a method of applying liquid silicon hydride without using a vacuum system. Japanese Unexamined Patent Publication No. 1-29661 discloses a method of forming a silicon-based thin film by liquefying a gaseous raw material on a cooled substrate, adsorbing it, and reacting it with chemically active atomic hydrogen. However, this method has a problem in that it is difficult to control the film thickness in addition to requiring a complicated device because the raw material silicon hydride is first vaporized and then cooled.

Further, Japanese Patent Application Laid-Open No. 7-267621 discloses a method of applying a low molecular weight liquid silicon hydride to a substrate, but this method is difficult to handle because the system is unstable. And because it is liquid,
When applied to a large area substrate, it is difficult to obtain a uniform film thickness.

On the other hand, although an example of a solid silicon hydride polymer is reported in British Patent GB-2077710A, a film cannot be formed by a coating method because it is insoluble in a solvent.

[0008]

SUMMARY OF THE INVENTION An object of the present invention is to form a silicon film which does not require a large-scale apparatus which is expensive and consumes a lot of energy and which can be applied to a large-area substrate and which can be easily formed. Another object of the present invention is to provide a method for forming a silicon film and a composition therefor.

Another object of the present invention is to provide a method of manufacturing a solar cell using the above-described silicon forming method of the present invention. Still another object of the present invention is to provide a silicon composition used in the method of the present invention. Other objects and advantages of the present invention will be apparent from the following description.

[0010]

According to the present invention, in order to solve the problems], the above objects and advantages of the present invention, the first 1, (A) formula Si _n R
_m (where n is an integer of 3 or more, and m is n to (2n
+2) and m R independently of one another are hydrogen, alkyl, phenyl or halogen, provided that all R of m are hydrogen and m = 2n.
And n is an integer of 7 or more. ) At least one silane compound selected from the group consisting of a polysilane compound represented by the formula (B), cyclopentasilane, cyclohexasilane, and silylcyclopentasilane, and a silane containing (C) silicon particles. Achieved by the composition.

The above objects and advantages of the present invention are, secondly, as follows:
Achieved by a method for forming a silicon film, which comprises the steps of (1) applying the silane composition onto a substrate to form a coating film, and (2) subjecting the coating film to heat treatment and / or phototreatment. To be done.

Thirdly, the above objects and advantages of the present invention are as follows. Thirdly, a solar cell having a structure in which at least two semiconductor thin films having different impurity concentrations and / or different kinds are laminated between a pair of electrodes is manufactured. a method of, (1) (a) formula Si _n R _m (where, n is an integer of 3 or more, m is n to (2n +
2) is an integer and m R are independently of each other a hydrogen atom, an alkyl group, a phenyl group or a halogen atom, provided that all of the m R are hydrogen atoms and m = 2n.
And n is an integer of 7 or more. ) A silane composition containing at least one silane compound selected from the group consisting of (B) cyclopentasilane, cyclohexasilane, and silylcyclopentasilane; and (C) silicon particles on a substrate. Forming a coating film by applying to (2)
This is achieved by a method for producing a solar cell, which comprises forming at least one layer of the semiconductor thin film by a method including a step of heat-treating and / or photo-treating the coating film.

Fourthly, the above objects and advantages of the present invention are as follows.
(A) Formula Si _n R _m (where n is an integer of 3 or more,
m is an integer from n to (2n + 2) and m Rs are independently of each other a hydrogen atom, an alkyl group, a phenyl group or a halogen atom, provided that all m Rs are hydrogen atoms and m = 2n. And n is an integer of 7 or more. (B) cyclopentasilane, (B) at least one silane compound selected from the group consisting of cyclohexasilane and silylcyclopentasilane, (C) silicon particles, and (D) boron compound, arsenic compound , A phosphorus compound, an antimony compound, and a general formula Si _a X _b Y _c (wherein X represents a hydrogen atom and / or a halogen atom, Y represents a boron atom or a phosphorus atom, and a represents an integer of 3 or more. , B is 1
A silane composition characterized by containing at least one compound selected from the group consisting of modified silane compounds represented by the following: an integer of a or more and a or less, and c is an integer of a or more and 2a + b + 2 or less) To be achieved.

Further, the above objects and advantages of the present invention are the fifth.
In the method for producing a solar cell having a structure in which at least two semiconductor thin films having different impurity concentrations and / or different kinds are laminated between a pair of electrodes, (1) the silane composition described above on a substrate At least one of the semiconductor thin films is formed as a p-type or n-type silicon thin film by a method including a step of applying a coating film on the substrate to form a coating film, and (2) a step of heat-treating and / or phototreating the coating film. This is achieved by a method for manufacturing a solar cell, which is characterized in that

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in detail below. The silane composition used in the present invention comprises the following components (A), (B) and (C), or (A),
It contains the components (B), (C) and (D) as essential components.

Component (A) The component (A) used in the present invention is represented by the formula Si _n R _m (where n is an integer of 3 or more, m is an integer of n to (2n + 2), and m pieces are included). R's are each independently a hydrogen atom, an alkyl group, a phenyl group or a halogen atom, provided that when all m R's are hydrogen atoms and m = 2n, n is an integer of 7 or more. Yes.).

Examples of the alkyl group represented by R include a methyl group, an ethyl group, an n-propyl group, an i-propyl group, an n-butyl group, a sec-butyl group, a t-butyl group,
n-pentyl group, i-pentyl group, neopentyl group, n
-Hexyl group, cyclohexyl group, n-heptyl group, n
Preferred examples include alkyl groups having 1 to 10 carbon atoms such as an -octyl group, an n-nonyl group, and an n-decyl group. Further, as the halogen atom, for example, fluorine, chlorine and bromine can be mentioned as preferable ones. The polysilane compound may have a chain shape, a ring shape, or a cage shape.

Of the above polysilane compounds, hydrogenated polysilane compounds in which all R are hydrogen atoms are preferably used. Such hydrogenated polysilane compound, hydrogenated chain polysilane represented by the formula Si _n H _{2n + 2,}
Hydrogenated cyclic polysilane represented by the formula Si _n H _2n, and hydrogenated cage-like polysilane compound represented by the formula Si _n H _n is preferably used. In addition, "cage-like" means a thing including a Prisman skeleton, a Cuban skeleton, a pentagonal prism skeleton, and the like.

However, n in each of the above formulas is an integer of 3 to 100,000, preferably 5 to 50,000 in the hydrogenated chain polysilane, and 7 to 100,000, preferably 8 in the hydrogenated cyclic polysilane. ~ 50,0
Is an integer of 0, and in hydrogenated cage polysilanes 6 to 100,000, preferably 7 to 50,000.
Is an integer.

In this case, if n is smaller than the above-mentioned minimum value, the film-forming property of the polysilane compound may be difficult, and if n is larger than the above-mentioned maximum value, the cohesive force of the polysilane compound may be caused. A decrease in solubility may be observed. Such polysilane compounds may be used alone or in combination of two or more.

The polysilane compound used in the present invention can be produced, for example, by the following method using a monomer having a desired structural unit as a raw material. (A) A method of dehalogenating polycondensation of halosilanes in the presence of an alkali metal (so-called "kipping method", J. Am. Che
m. Soc. , 110 , 2342 (1988) and M.
acromolecules, 23 , 3423 (199
0)); (b) Method of dehalogenating polycondensation of halosilanes by electrode reduction (J. Chem. Soc., C.
hem. Commun. 1161 (1990) and J. Chem. Soc. Chem. Commun. ，
896 (1992)); (c) A method for dehydrogenative condensation polymerization of hydrosilanes in the presence of a metal catalyst (JP-A-4-26
No. 334551): (d) Method by anionic polymerization of disilene crosslinked with biphenyl or the like (Macr
o molecules, 23, 4494 (1990)
reference). (E) After synthesizing the cyclic silicon compound substituted with a phenyl group or an alkyl group by the above method, a known method (for example, Z. Anorg. Allg. Chem., 4
59 , 123-130 (1979), E.I. Henggg
e et al Mh. Chem. Volume 106, Pages 503, 197
It can be converted to a hydro-substituted product, a halogen-substituted product or the like after 5 years), and (f) the silane compound synthesized by the above method can be irradiated with light to obtain a higher molecular weight polysilane compound.

When a polysilane compound is synthesized by irradiating a silane compound with light, a silane compound as a raw material is represented by the formula Si _i H _{2i + 2} (where i is an integer of 2 to 8,
It is preferably an integer of 2 to 4. ) A hydrogenated chain silane compound represented by the formula: Si _j H _{2 j} (where j is an integer of 3 to 10, preferably an integer of 3 to 6) A compound and a hydrogenated cage silane compound represented by the formula Si _k H _k (k is an integer of 6 to 10) are preferable. Of these, the hydrogenated cyclic silane compounds are more preferable, and at least one compound selected from the group consisting of cyclopentasilane, cyclohexasilane, and silylcyclopentasilane is particularly preferable. These are respectively represented by the following formulas (1) to
It is represented by (3).

[0023]

[Chemical 1]

These silane compounds can be produced via decaphenylcyclopentasilane and dodecaphenylcyclopentasilane produced from diphenyldichlorosilane.

These silane compounds may be used alone or in the form of 2
It can be used as a mixture of two or more species.

When irradiating light, in addition to visible light, ultraviolet light, far ultraviolet light, low-pressure or high-pressure mercury lamp, deuterium lamp, discharge light of rare gas such as argon, krypton, xenon, YAG laser, argon. laser,
Carbon dioxide laser, XeF, XeCl, XeBr, Kr
An excimer laser such as F, KrCl, ArF, or ArCl can be used as a light source. As these light sources, those having an output of 10 to 5,000 W are preferably used. Usually 100 to 1,000 W is sufficient. The wavelength of these light sources is not particularly limited as long as it is absorbed by the silane compound as a raw material, but 170n
m-600 nm is preferable.

The temperature for the light irradiation treatment is preferably room temperature to 300 ° C. or lower. The processing time is about 0.1 to 30 minutes. The light irradiation treatment is preferably performed in a non-oxidizing atmosphere. Further, the light irradiation treatment may be carried out in the presence of a suitable solvent. As such a solvent, those similar to the solvent described below as an optional addition component of the composition of the present invention can be used.

Component (B) The component (B) used in the present invention is at least one silane compound selected from the group consisting of cyclopentasilane, cyclohexasilane and silylcyclopentasilane. In the present invention, these silane compounds can be used alone or as a mixture of two or more kinds.

When the polysilane compound as the above-mentioned component (A) becomes a high molecular weight compound having a degree of polymerization n in the formula Si _n R _m of about 10 or more, the polysilane compound is soluble in a general-purpose solvent such as a hydrocarbon solvent or an ether solvent. Since it becomes extremely low and becomes substantially insoluble, it was virtually impossible to form such a polysilane compound on a substrate and convert it into a silicon film.

In the present invention, it was found that a specific liquid silane compound (the above-mentioned component (B)) exhibits a good solubility in such an originally solvent-insoluble polysilane compound, and the polysilane compound is used as a semiconductor thin film. It has become possible to use it as a raw material. By using such a relatively high molecular weight polysilane compound as a raw material for the silicon film, there is an advantage that the formed film becomes dense and has excellent uniformity and high quality.

The ratio of the polysilane compound to the silane compound constituting the solution composition of the present invention is preferably 0.01 to 1,000% by weight, more preferably 0.0.
It is 5 to 500% by weight, particularly preferably 0.1 to 100% by weight. If this value is less than 0.01% by weight, the coating film may be too thin after coating to finally form a continuous silicon film. On the other hand, if this value exceeds 1,000% by weight, the polysilane compound may not be completely dissolved.

Component (C) As the silicon particles used in the present invention, commercially available ones or those synthesized by the method described in JP-A No. 11-49507 can be used. The purity of the silicon particles is preferably 99% or more, more preferably 99.9% or more, and particularly preferably 99.99% or more. If it is less than 99%, the formed silicon film may not exhibit semiconductor characteristics, which is not preferable.

The particle size of the silicon particles is preferably 0.
005 to 1,000 μm, particularly preferably 0.005
The particle size is 100 μm, the particle size can be appropriately selected according to the desired film thickness, and the shape and particle size distribution of the silicon particles are not particularly limited. The amount of silicon particles used is preferably 0.01 to 20 with respect to the total amount of the components (A) and (B).
It is 0% by weight, more preferably 0.1 to 100% by weight.

The silicon particles may be amorphous or crystalline, but if it is desired to form a good quality crystalline silicon thin film at 600 ° C. or lower, it is preferable to use crystalline silicon particles. When crystalline silicon particles are used, they act as crystal nuclei when a silane composition of the present invention is applied and heat and / or phototreated to form a silicon film, and crystal growth can be promoted. Further, by dispersing the silicon particles in the silane composition,
Adhesion to the substrate during the formation of the silicon film is significantly improved, and even if the film thickness is significantly increased, a uniform silicon film can be formed without causing cracks or peeling.

Component (D) The silane composition of the present invention contains the above-mentioned component (A), component (B) and component (C) as essential components, but it must further contain component (D). You can

The component (D) used in the present invention is a boron compound, an arsenic compound, a phosphorus compound, an antimony compound,
And the formula Si _a X _b Y _c (where X is a hydrogen atom and / or
Or a halogen atom, Y represents a boron atom or a phosphorus atom, a represents an integer of 3 or more, b represents an integer of 1 or more and a or less, and c represents an integer of a or more and 2a + b + 2 or less). Is at least one compound selected from the modified silane compounds.

Examples of the boron compound include boron hydrides, boron alkylates, boron arylates, and boron compounds having a trimethylsilyl group. Specific examples of these include B ₂ H ₆ and BP.
_{h 3, BMePh 2, B (} t-Bu) 3, B (SiMe 3)
₃ , PhB (SiMe ₃ ) ₂ , Cl ₂ B (SiMe ₃ ) and the like. Here, Ph means a phenyl group, and M
e means a methyl group. The same applies to the following.

Examples of the arsenic compound include arsenic alkanes.
Killed compounds, arsenic aryl compounds and trimethylsilyl groups
And an arsenic compound having As specific examples of these
For example, AsPh₃, AsMePh₂, As (t-
Bu)₃, As (SiMe₃) ₃, PhAs (SiMe₃)
₂, Cl₂As (SiMe₃) And the like. here,
t-Bu means a tertiary butyl group. Also,
The same is true.

Examples of the phosphorus compound include phosphorus alkyl compounds, phosphorus aryl compounds and phosphorus compounds having a trimethylsilyl group. Specific examples of these include PPh ₃ , PMePh ₂ , P (t-Bu) ₃ and P
(SiMe ₃ ) ₃ , PhP (SiMe ₃ ) ₂ , Cl ₂ P (S
iMe ₃ ) _{3 and the} like.

Examples of the antimony compound include antimony alkyl compounds and antimony aryl compounds. Specific examples thereof include SbP
_{h 3, SbMePh 2, Sb (} t-Bu) 3 and the like.

In addition to these, SbAs (SiMe ₃ ) ₂ and Sb ₂ As (Si containing antimony and arsenic in one molecule
Me ₃ ) and the like are also preferably used.

The above formula Si _a X _b Y _c (wherein X represents a hydrogen atom and / or a halogen atom, Y represents a boron atom or a phosphorus atom, a represents an integer of 3 or more, and b represents 1 or more. represents an integer less than or equal to a, and c is greater than or equal to a and is (2a + b +
2) represents at least the following integer), as a specific example of at least one compound selected from the modified silane compounds,
For example, the compound represented by the following formula can be mentioned.

[0043]

[Chemical 2]

[0044]

[Chemical 3]

SiH ₃ (SiH ₂ ) _e BH ₂ compound 21 SiCl ₃ (SiCl ₂ ) _e BCl ₂ compound 22 In the above formula, d represents an integer of 0 or more, and e represents an integer of 2 or more.

Although only the modified silane compound containing a boron atom has been exemplified in the above formula, the modified silane compound containing a phosphorus atom also has a skeleton similar to that of the above formula, that is, the boron atom of each of the above formulas. It is possible to exemplify one in which is changed to a phosphorus atom.

As a method for synthesizing these compounds, a monomer such as boron halide, phosphorus halide or silane having each structural unit is usually used as a raw material and, for example, the same method as the above-mentioned component (A) is used. Can be synthesized.

When the silane composition used in the present invention contains the component (D), its content is preferably 100 parts by weight or less, more preferably 0.01 part by weight, per 100 parts by weight of the component (A). ˜50 parts by weight, particularly preferably 0.1 to 10 parts by weight. Other Components The composition used in the present invention contains the above-mentioned component (A), component (B), component (C) and optionally component (D) as essential components. Other components may be contained as long as they are not impaired. Examples of such other components include a surfactant.

Such surfactants can be cationic, anionic, zwitterionic, or nonionic. In particular, nonionic surfactants improve the wettability of the composition to the object to be coated, improve the leveling property of the coated film, and help prevent the occurrence of crushing of the coating film and the occurrence of orange peel skin. Therefore, it can be preferably used.

Examples of such nonionic surfactants include fluorochemical surfactants having a fluorinated alkyl group or perfluoroalkyl group, and polyether alkyl surfactants having an oxyalkyl group.

Examples of the above-mentioned fluorine-containing surfactant include F-top EF301, EF303, EF352.
(Manufactured by Shin-Akita Kasei Co., Ltd.), Megafac F171, F
173 (manufactured by Dainippon Ink and Chemicals, Inc.), Asahi Guard AG7
10 (manufactured by Asahi Glass Co., Ltd.), Florard FC-170C,
FC430 and FC431 (Sumitomo 3M Limited)
Manufactured), Surflon S-382, SC101, SC1
02, SC103, SC104, SC105, SC106 (manufactured by Asahi Glass Co., Ltd.), BM-1000, SC1
100 (manufactured by BM Chemie), Schsego
-Fluor (manufactured by Schwegmann), C ₉ F ₁₉
CONHC ₁₂ H ₂₅ , C ₈ F ₁₇ SO ₂ NH- (C ₂ H ₄ O) ₆
H, C ₉ F ₁₇ O (Pluronic L-35) C ₉ F ₁₇ , C ₉
F ₁₇ O (Pluronic P-84) C ₉ F ₁₇ , C ₉ F ₁₇ O
(Tetronic-704) (C ₉ F ₁₇ ) _{2 and the} like can be mentioned. (Here, Pluronic L-35: Asahi Denka Kogyo KK, polyoxypropylene-polyoxyethylene block copolymer, average molecular weight 1,900; Pluronic P-84: Asahi Denka Kogyo KK, polyoxy Propylene-polyoxyethylene block copolymer, average molecular weight 4,200; Tetronic-704: Asahi Denka Co., Ltd., N, N, N ', N'-tetrakis (polyoxypropylene-polyoxyethylene block copolymer Polymer),
The average molecular weight is 5,000. ) Further, as the polyether alkyl-based surfactant, polyoxyethylene alkyl ether, polyoxyethylene allyl ether, polyoxyethylene alkylphenol ether, polyoxyethylene fatty acid ester, sorbitan fatty acid ester, polyoxyethylene sorbitan fatty acid ester, oxyethyleneoxy A propylene block polymer etc. can be mentioned.

Specific examples of these polyether alkyl-based surfactants include Emulgen 105, 430, 810, 920, Rhodol SP-40S and TW-.
L120, Emanol 3199, Same 4110, Exel P-40S, Bridge 30, Same 52, Same 72, Same 92,
Examples include Arassel 20, Emazol 320, Tween 20, 60, Merge 45 (all manufactured by Kao Corporation), Noniball 55 (manufactured by Sanyo Kasei Co., Ltd.) and the like. Examples of nonionic surfactants other than the above include polyoxyethylene fatty acid ester, polyoxyethylene sorbitan fatty acid ester, polyalkylene oxide block copolymer, and the like. Specifically, Chemistat 2500 (Sanyo Chemical Co., Ltd.) Manufactured), SN-EX92
28 (manufactured by San Nopco Co., Ltd.) and Nonal 530 (manufactured by Toho Chemical Industry Co., Ltd.).

The amount of such a surfactant used is preferably 10 parts by weight or less, particularly preferably 0.1 to 5 parts by weight, based on 100 parts by weight of the total composition. here,
If it exceeds 10 parts by weight, the resulting composition is likely to foam, and thermal discoloration may occur, which is not preferable.

The silane composition used in the present invention may contain a solvent in addition to the above components. The solvent that can be used in the present invention preferably has a boiling point of 30 to 3 at atmospheric pressure.
It is one at 50 ° C. When the boiling point of the solvent used is lower than 30 ° C., when forming a coating film by coating, the solvent may evaporate first and it may be difficult to form a good coating film. On the other hand, when the boiling point is higher than 350 ° C., the dissipation of the solvent is delayed, the solvent is likely to remain in the coating film, and it may be difficult to obtain a good-quality silicon film even after the heat and / or light treatment in the subsequent step. .

The solvent which can be used in the present invention includes (A)
The component, the component (B), the component (C), and the component (D), which is optionally contained, are not particularly limited as long as they do not precipitate, phase-separate, or react with them. For example, n -Pentane, n-hexane, n-heptane, n-octane, decane, dodecane, cyclohexane, cyclooctane, styrene, dicyclopentane, benzene, toluene, xylene, cumene, durene, indene, tetrahydronaphthalene, decahydronaphthalene, squalane. Hydrocarbon solvents such as diethyl ether, dipropyl ether, ethylene glycol dimethyl ether, ethylene glycol diethyl ether, ethylene glycol methyl ethyl ether, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, diethylene Recall methyl ethyl ether, tetrahydrofuran tetrahydropyran, 1,2
Ether-based solvents such as dimethoxyethane, bis (2-methoxyethyl) ether, p-dioxane, tetrahydrofuran; and propylene carbonate, γ-butyrolactone, N-methyl-2-pyrrolidone, dimethylformamide, acetonitrile, dimethylsulfoxide, methylene chloride, Mention may be made of polar solvents such as chloroform. Of these, hydrocarbon solvents are preferable from the viewpoint of stability of the solution. These solvents can be used alone or as a mixture of two or more kinds.

When the above-mentioned solvent is used, the amount thereof can be appropriately adjusted according to the desired thickness of the semiconductor thin film, but preferably the above-mentioned components (A), (B) and (C). Component, or (A) component, (B) component,
The total amount of the components (C) and (D) is 100 parts by weight or less, particularly 10,000 parts by weight or less, and particularly preferably 5,000% by weight or less. If it exceeds 10,000 parts by weight, a polysilicon compound may be precipitated, which is not preferable.

The composition used in the present invention may be subjected to a light irradiation treatment if desired and then subjected to a semiconductor thin film forming step. As the light irradiation conditions at this time, the same conditions as the light irradiation treatment performed in the step of converting the composition coating film into a semiconductor thin film, which will be described later, can be adopted.

Method for Forming Solar Cell A method for manufacturing a solar cell according to the present invention is a method for producing a solar cell having a structure in which at least two semiconductor thin films having different impurity concentrations and / or types are laminated between a pair of electrodes. At this time, at least one layer of the semiconductor thin film is formed from the silane composition. In the present invention, a semiconductor thin film is formed by applying the above silane composition onto a substrate and treating it with heat and / or light.

As the type of substrate used at this time,
For example, glass, metal, plastic, ceramics, etc. can be mentioned. As the glass, for example, quartz glass, borosilicate glass, soda glass, lead glass, lanthanum glass, etc. can be used. Examples of metals include gold, silver, copper, nickel, silicon, aluminum, iron,
In addition to tungsten, stainless steel can be used. Further, glass, plastic substrate or the like having a conductive metal or a conductive metal oxide film such as ITO on the surface can be used. As the plastic, for example, polyimide, polyether sulfone, norbornene ring-opening polymer and hydrogenated product thereof can be used. Furthermore, the shape of these materials is not particularly limited to lumps, plates, films, etc., and the surface on which the coating film is to be formed may be flat or non-planar with steps. When the step of converting the coating film into a semiconductor thin film includes a heat treatment step, a substrate made of a material that can withstand the heat is preferable.

When applying the silane composition onto the substrate,
The film thickness is preferably 0.005 to 10 μm by an appropriate method such as a spray method, a roll coating method, a curtain coating method, a spin coating method, a screen printing method, an offset printing method, an inkjet method, a dip coating method.
m, particularly preferably 0.01 to 5 μm. At this time, when the silane composition contains a solvent, the film thickness should be understood as a value after removing the solvent.

The above coating film forming step is preferably carried out in a non-oxidizing atmosphere. In order to realize such an atmosphere, an atmosphere that does not substantially contain an oxidizing substance such as oxygen or carbon dioxide may be used. Specifically,
Atmospheres in nitrogen, hydrogen, noble gases and mixed gases thereof can be preferably used.

Such a coating process can be carried out while applying a light irradiation treatment. As the light irradiation conditions at this time, the same conditions as the light irradiation treatment performed in the step of converting the composition coating film into a semiconductor thin film, which will be described later, can be adopted.

During the heat treatment for converting the composition coating film into a semiconductor thin film, it is preferably under a non-oxidizing atmosphere, preferably 100 to 1,000 ° C., more preferably 200 to 85.
At 0 ° C, more preferably 300 to 750 ° C, preferably 1 to 600 minutes, more preferably 5 to 30 minutes.
Heat treatment is performed for 0 minutes, more preferably for 10 to 150 minutes.
Generally, an amorphous semiconductor thin film is obtained at a temperature of about 550 ° C. or lower, and a polycrystalline semiconductor thin film is obtained at a temperature of 550 ° C. or higher. When the ultimate temperature is lower than 300 ° C., the thermal decomposition of the polysilane compound does not proceed sufficiently and the desired silicon film may not be formed.

The above non-oxidizing atmosphere can be realized by heat treatment in an argon atmosphere or an argon atmosphere containing hydrogen.

In the light treatment for converting the composition coating film into a semiconductor thin film, visible light, ultraviolet light, far ultraviolet light, low pressure or high pressure mercury lamp, deuterium lamp, argon, krypton, xenon, etc. may be used. In addition to rare gas discharge light, YAG laser, argon laser, carbon dioxide gas laser, XeF, XeCl, XeBr, KrF,
An excimer laser such as KrCl, ArF or ArCl can be used as a light source. As these light sources, those having an output of 10 to 5,000 W are generally used, but 100 to 1,000 W is usually sufficient.
The wavelength of these light sources is not particularly limited as long as the polysilane compound in the composition or the coating film absorbs even a little, but 170 nm to 600 nm is preferable.

The temperature during the light irradiation treatment is preferably room temperature to 300 ° C., and the treatment time is about 0.1 to 30 minutes. These light irradiation treatments are preferably performed in a non-oxidizing atmosphere similar to the coating film forming step.

In the present invention, the semiconductor thin film is formed as described above. At this time, the composition used in the present invention contains the component (A), the component (B) and the component (C) ( When the component (D) is not contained, the formed semiconductor thin film is an i-type semiconductor thin film. The i-type semiconductor thin film thus formed can be made into a p-type semiconductor thin film by undergoing a step of doping a boron atom, while a step of doping at least one atom selected from arsenic, phosphorus and antimony is performed. N by passing
Can be a semiconductor of the type.

At this time, the composition used in the present invention is the component (A), the component (B), the component (C) and the component (D).
When the component (D) component contains a boron compound, the formed semiconductor thin film becomes a p-type semiconductor thin film, while the component (D) contains an arsenic compound, a phosphorus compound and an antimony compound. When it contains at least one compound selected from the following, it becomes an n-type semiconductor thin film.

Further, a coating film of a composition containing the component (A), the component (B) and the component (C) but not the component (D) on the substrate, the component (A) and the component (B), A p-type or n-type semiconductor thin film can also be formed by laminating a coating film of a composition containing the component (C) and the component (D), and then performing heat and / or light treatment. it can.

The p-type or n-type semiconductor thin film thus formed is further doped with a boron atom or at least one atom selected from arsenic, phosphorus and antimony to obtain an impurity concentration in the semiconductor thin film. Can be increased. As the doping step,
In addition to the well-known thermal diffusion method and ion implantation method,
It can also be carried out by forming a coating film containing the component (D) on the semiconductor thin film formed as described above, and then performing heat treatment.

To form a coating film containing the component (D) on the semiconductor thin film, a composition containing the component (D) and optionally a solvent, or the component (D) and This can be carried out by applying the composition containing the component (B) and optionally a solvent, and then removing the solvent. As the solvent used at this time, those exemplified as the solvent of the composition used in the present invention can be used. The component (D) concentration in the composition is preferably 1 to 100% by weight. As the heat treatment conditions at this time, the same conditions as those described above as the heat treatment at the time of forming the semiconductor thin film can be adopted.

When the semiconductor thin film obtained as described above is amorphous, it can be converted into a polycrystalline semiconductor thin film by further treating it with high energy light such as an excimer laser. The atmosphere for carrying out this irradiation treatment is preferably the same non-oxidizing atmosphere as in the coating film forming step.

The solar cell manufactured according to the present invention has a structure in which at least two semiconductor thin films having different impurity concentrations and / or types are laminated between a pair of electrodes, and pn, pin,
It has a structure having a semiconductor junction such as ip or in. The solar cell manufactured by the present invention is one in which at least one layer of the above-mentioned laminated semiconductor thin films is formed by the above method. It is also possible to form all the layers of the semiconductor thin films to be laminated by the above method. Further, all of the laminated semiconductor thin films may be amorphous, all may be polycrystalline semiconductor thin films, or both may be mixed.

The solar cell manufactured by the manufacturing method of the present invention comprises, in addition to the above-mentioned semiconductor thin film, a conductive film for electrodes and wiring,
In addition, if necessary, an insulating film is provided, but these are not particularly limited, and include, for example, metal films generally used in solar cells, transparent conductive films such as ITO, and SiO ₂
An insulating film such as the above can be used. As a forming method thereof, a general vapor deposition method, a sputtering method, a CVD method or the like can be used, and also a liquid material which does not require a vacuum process can be used.

As a method of forming a conductive film from a liquid material, for example, a method of using a suspension in which metal particles are dispersed in an organic solvent, a method of plating, or a method of applying an organic compound containing indium and tin and then performing heat treatment And a method of forming an ITO thin film.

As a method for forming an insulating film from a liquid material, for example, a coating film of the above-mentioned semiconductor thin film forming composition is heat-treated and / or irradiated with light in the presence of oxygen and / or ozone, for example, in the air. There is a method of forming by treatment or applying polysilazane to the substrate and then converting it into SiO ₂ by heat treatment.

In the method of manufacturing a solar cell of the present invention, the above-mentioned silicon film, conductive film, and insulating film may be used by patterning after film formation. As a method therefor, a mask method, a lithography method and the like are generally used. In addition to various methods, it is also possible to use a method of simultaneously applying and patterning a liquid material using an inkjet method.

[0078]

The present invention will be described in detail below with reference to examples, but the present invention is not limited to these examples.

Synthesis Example 1 After replacing the inside of a 4-necked flask having a capacity of 3 L equipped with a thermometer, a cooling condenser, a dropping funnel and a stirrer with argon gas, dried tetrahydrofuran 1 L
And 18.3 g of lithium metal were charged, and argon gas was bubbled. While stirring this suspension at 0 ° C., 333 g of diphenyldichlorosilane was added from a dropping funnel,
After the dropwise addition was completed, stirring was continued for 12 hours at room temperature until the lithium metal completely disappeared. The reaction mixture was poured into 5 L of ice water to precipitate the reaction product. This precipitate was separated by filtration, washed well with water, then washed with cyclohexane, and vacuum dried to obtain 140 g of a white solid. 100 g of this white solid and 1,000 mL of dry cyclohexane
Was charged into a 2 L flask, 4 g of aluminum chloride was added, and hydrogen chloride gas dried at room temperature was bubbled for 8 hours while stirring. Here, separately, 40 g of lithium aluminum hydride and 400 mL of diethyl ether were charged into a 3 L flask, the above reaction mixture was added with stirring at 0 ° C. under an argon atmosphere, and the mixture was stirred at the same temperature for 1 hour and further at room temperature for 12 hours. Stirring was continued. After removing by-products from the reaction mixture, vacuum distillation was carried out at 70 ° C. and 10 mmHg to obtain 10 g of a colorless liquid. This is I
From each spectrum of R, ¹ H-NMR, ²⁹ Si-NMR and GC-MS, it was found to be cyclopentasilane.

Synthesis Example 2 Under an argon atmosphere, 10 g of the cyclopentasilane obtained in Synthesis Example 1 was added to a 100 mL flask and irradiated with a 500 W high pressure mercury lamp for 30 minutes while stirring to obtain a white solid. The white solid obtained here was insoluble in toluene and cyclohexane. When 100 g of the cyclopentasilane obtained in Synthesis Example 1 was added to this, a colorless transparent solution was obtained.

Synthesis Example 3 A 4-necked flask having a capacity of 1 L equipped with a thermometer, a condenser, a dropping funnel and a stirrer was replaced with argon gas, and then dried in 500 m of tetrahydrofuran.
L and 9 g of lithium metal were charged and bubbled with argon gas. While stirring this suspension at room temperature, a mixture of 126 g of diphenyldichlorosilane and 25 g of boron tribromide was added from a dropping funnel. After continuing the reaction until the lithium metal disappeared completely, the reaction mixture was poured into ice water to precipitate the reaction product. The precipitate was filtered off, washed thoroughly with water, and dried to obtain 90 g of a silicon compound containing a phenyl group and boron. 90g of this compound
Dissolved in 500 mL of toluene, 4 g of aluminum chloride
Was added, and hydrogen chloride gas dried under ice cooling was bubbled for 8 hours with stirring. Separately, 12 g of lithium aluminum hydride and 250 mL of diethyl ether were separately charged into a 2 L flask, and the above reaction mixture was added with stirring at 0 ° C. under an argon atmosphere, followed by stirring at the same temperature for 1 hour and further at room temperature for 12 hours. Stirring was continued. After removing the aluminum compound, the product was concentrated and purified to obtain 10 g of a target modified silane compound containing boron. As a result of elemental analysis, this was found to be Si ₅ H ₁₁ B.

Synthesis Example 4 A modified silane compound containing phosphorus was obtained in the same manner as in Synthesis Example 3 except that 27 g of phosphorus tribromide was used instead of 25 g of boron tribromide. . As a result of elemental analysis, this was found to be Si ₅ H ₁₁ P.

Example 1 Silicon powder manufactured by Aldrich (purity 99.9995%)
10 g of silicon particles having a particle diameter of 0.2 to 1 μm obtained by classifying was mixed with 40 g of the solution prepared in Synthesis Example 2 under a nitrogen atmosphere and uniformly dispersed by a homogenizer. The silane composition thus prepared was spin-coated on a glass substrate at 1,000 rpm in a nitrogen atmosphere, and the spin coating was performed at 200 ° C. for 2 hours.
After prebaking for 10 minutes, it was baked at 400 ° C. for 10 minutes.
Then, it was further baked at 500 ° C. for 30 minutes. As a result, a polycrystalline silicon film having a film thickness of 2 μm was formed on the glass substrate. The X-ray diffraction pattern is shown in FIG.

Example 2 A solar cell having a structure as schematically shown in FIG. 2 was prepared by the following method on a quartz substrate on which a transparent conductive film ITO was formed.

First, in order to form a p-type silicon film on the ITO film, the Si ₅ H ₁₁ B obtained in Synthesis Example 3 was deposited on the ITO film.
A silane composition was prepared by mixing 2 g and 10 g of the silane composition obtained in Example 1. A 0.4 μm thick polycrystalline silicon film was formed from this composition in the same manner as in Example 1 in an argon atmosphere.

Next, in order to deposit an i-type silicon film, the composition obtained in Example 1 was spin-coated at 1,000 rpm on the substrate on which the silicon film was formed under an argon atmosphere, Firing was performed in the same manner as in No. 1 to form an i-type polycrystalline silicon film having a film thickness of 2 μm.

Further, for laminating an n-type silicon film, 0.2 g of Si ₅ H ₁₁ P obtained in Synthesis Example 4 and 10 g of the solution prepared in Example 1 were mixed to prepare a coating solution. . This solution was spin-coated at 2,000 rpm on a substrate on which the above silicon film was laminated in an argon atmosphere, and baked by the same baking method as in Example 1 to obtain a film thickness of 0.4.
An n-type polycrystalline silicon film of μm was formed.

An aluminum film of 0.5 μm is vapor-deposited on a part of the laminated film using a mask from the laminated film of the pin connection structure formed as described above, and a portion without the aluminum film is formed on the lower ITO film. Etching was performed until the exposed portions were exposed to manufacture a solar cell having a structure as shown in FIG. The photovoltaic efficiency of this solar cell was measured to find the conversion efficiency, which was 14.0%.

[0089]

According to the present invention, it is possible to easily and inexpensively form a semiconductor thin film, which does not require a large-scale apparatus that is expensive and consumes a lot of energy, and can be applied to a large-area substrate. Is provided.

[Brief description of drawings]

1 is an X-ray diffraction diagram of a polycrystalline silicon film obtained in Example 1. FIG.

FIG. 2 is a schematic diagram showing the structure of a solar cell.

[Explanation of symbols]

1; substrate 2; ITO film 3; p-type silicon film 4; i-type silicon film 5; n-type silicon film 6; Aluminum film 7; probe electrode

   ─────────────────────────────────────────────────── ─── Continued front page    F term (reference) 4G072 AA01 BB09 BB12 GG01 GG02                       HH02 HH28 HH29 MM01 RR12                       RR30 UU01 UU02                 4J002 CP011 DA067 DA117 EX006                       EX026 EY016 HA05                 4J038 DL032 DL171 DL172 KA20                       PA17 PA19 PB09                 5F051 AA03 AA05 BA12 BA14 CA02                       CA03 CA04 CA06 CA20 CB13                       CB24 CB25 FA04

Claims (9)

[Claims] 1. A formula (A) Si _n R _m (where n is an integer of 3 or more, and m is n to (2n +).
2) is an integer and m R are independently of each other a hydrogen atom, an alkyl group, a phenyl group or a halogen atom, provided that all of the m R are hydrogen atoms and m = 2n.
And n is an integer of 7 or more. ) At least one silane compound selected from the group consisting of a polysilane compound represented by the formula (B), cyclopentasilane, cyclohexasilane, and silylcyclopentasilane, and a silane containing (C) silicon particles. Composition. 2. A method comprising: (1) a step of applying the silane composition according to claim 1 on a substrate to form a coating film; and (2) a step of heat-treating and / or phototreating the coating film. A method for forming a characteristic silicon film. 3. A method for producing a solar cell having a structure in which at least two semiconductor thin films having different impurity concentrations and / or types are laminated between a pair of electrodes, the method comprising the steps of: (1) Formula Si _n R _m (where n is an integer of 3 or more, and m is n to (2n +
2) is an integer and m R's are independently of each other a hydrogen atom, an alkyl group, a phenyl group or a halogen atom, provided that all m R's are hydrogen atoms and m = 2n.
And n is an integer of 7 or more. ) A silane composition containing at least one silane compound selected from the group consisting of (B) cyclopentasilane, cyclohexasilane, and silylcyclopentasilane; and (C) silicon particles on a substrate. Forming a coating film by applying to (2)
A method for producing a solar cell, comprising forming at least one layer of the semiconductor thin film by a method including a step of heat-treating and / or photo-treating the coating film. 4. The method according to claim 3, wherein the semiconductor thin film formed is an i-type silicon thin film. 5. A step (3) of forming a p-type or n-type silicon thin film by doping at least one atom selected from the group consisting of boron, arsenic, phosphorus and antimony after the step (2). The method of claim 3, further comprising: 6. The formula (A) Si_nR_m (Here, n is an integer of 3 or more, and m is n to (2n +
2) is an integer and m R are independently hydrogen atoms.
Child, an alkyl group, a phenyl group or a halogen atom
Provided that all R of m are hydrogen atoms and m = 2n
And n is an integer of 7 or more. )so
Represented polysilane compound, (B) cyclopentasila
, Cyclohexasilane and silylcyclopentasila
At least one silane compound selected from the group consisting of
Object, (C) silicon particles and (D) boron compound,
Arsenic compounds, phosphorus compounds, antimony compounds and formula S
i _aX_bY_c(Where X is a hydrogen atom and / or halo
Represents a gen atom, and Y represents a boron atom or a phosphorus atom.
, A represents an integer of 3 or more, b is an integer of 1 or more and a or less
And c is an integer of a or more and (2a + b + 2) or less.
Selected from the group consisting of modified silane compounds represented by
Characterized by containing at least one compound
Silane composition. 7. A method for producing a solar cell having a structure in which at least two semiconductor thin films having different impurity concentrations and / or different kinds are laminated between a pair of electrodes, the method comprising the steps of (1) and (6). At least one of the semiconductor thin films is p-type or n-type by a method including a step of applying a silane composition onto a substrate to form a coating film, and (2) a step of heat-treating and / or photo-treating the coating film. The method for manufacturing a solar cell is characterized by forming the thin film as a silicon thin film. 8. The method according to claim 3, wherein the semiconductor thin film formed is an amorphous silicon thin film. 9. The method according to claim 3, wherein the semiconductor thin film formed is a polycrystalline silicon thin film.