JP2012059871A - Silicon-germanium film and method of producing silicon-germanium film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a composition used for obtaining a silicon semiconductor film for a solar cell by formation of a coating film in the air and heating or laser irradiation of its precursor, and to provide a coating type silicon-germanium film and a method of producing a silicon-germanium film.SOLUTION: A germanium resin synthesized using germanium tetrachloride as a starting material and having a main chain skeleton of three-dimensional Ge-Ge bond and a side chain of an organic substituent, and silicon particles are mixed and ground so that the germanium resin covers the surface of the silicon particles. The mixed and ground matter is mixed in an organic dispersion medium to produce a composition, and a film of the composition is formed and subjected to heat treatment or laser irradiation.

Description

  The present invention relates to a silicon-germanium film that can be used as a solar cell or a semiconductor. In particular, the film can be formed in the air without using an expensive vacuum apparatus or sputtering apparatus, and the manufacturing process cost is low. The present invention relates to a silicon-germanium film and a method for producing a silicon-germanium film.

  Due to the emergence of energy environment problems, the spread of solar cells is now being sought. In connection with this, in the case of crystalline solar cells, there are price and resource issues due to the demand and supply of silicon substrate materials. In such solar cells, there are problems of film formation speed and apparatus cost resulting from the formation of a thin film from gas in a gas phase (for example, see Non-Patent Document 1).

  In the spread of solar cells, cost reduction is one of the issues. Therefore, a material and a manufacturing process for a coating-type solar cell that can greatly reduce the cost of the apparatus and can increase the area are required (for example, see Non-Patent Document 2). In non-silicon-based solar cells, CIGS-based solar cells have already been put into practical use (for example, see Non-Patent Document 3).

  However, considering the amount of resources, low toxicity, and environmental impact, it is significant that silicon solar cells can be manufactured at low cost by the coating method. For this reason, research and development on materials and manufacturing methods aiming at coating-type silicon solar cells have been conducted at home and abroad.

  In particular, in the United States, the development of a coating type silicon solar cell using silicon ink using silicon nanoparticles is remarkable. Innovalight, Inc. of the United States made a coated solar cell using silicon ink composed of silicon nanoparticles, and achieved a high conversion efficiency of 19% (for example, see Non-Patent Document 4). Many technologies have been developed (see, for example, Patent Document 1).

  The US company Nonogram is also developing a technology relating to a method for producing a thin film for semiconductor use by a printing method using a silicon nanoparticle ink (see, for example, Patent Document 2).

  In Japan, technological development aimed at manufacturing coated silicon semiconductor films and solar cells using silicon fine particles has been carried out (see, for example, Patent Documents 3 and 4). It has not reached.

  The formation method of the silicon-based semiconductor film by the coating method is based on a nanometer-sized silicon fine particle, a surface modified body thereof, a composition containing them, a dispersion medium, and a solvent. On the other hand, the inventor of the present invention preceded them by synthesizing organically substituted silicon trichloride or silicon tetrachloride as a raw material, the main chain skeleton is composed of a three-dimensional Si-Si bond, and the side chain is organically substituted. A nanocluster type silicon resin having a group (see, for example, Patent Document 6, Non-Patent Documents 5, 6, and 7) and a Ge—Ge bond having a three-dimensional main chain skeleton synthesized from germanium tetrachloride Synthesis of nanocluster type germanium resin (for example, see Patent Document 7 and Non-Patent Documents 8 and 9) having an organic substituent in the side chain, and heating or laser irradiation using them as a precursor film In addition, techniques relating to the formation of silicon and germanium films accompanied by desorption of organic side chains by thermal decomposition have been reported (for example, see Patent Documents 5 and 7, and Non-Patent Documents 6 and 9).

  Regarding a semiconductor film manufacturing method using a resin composed of Si—Si bond or a resin composed of Ge—Ge bond as a precursor, there is a report of a technique or concept similar to that previously reported by the present inventor, In later years, it was also conducted by other research groups (for example, see Patent Document 8).

In these technologies, a polymer having an organic substituent is converted into a perhydrosilane and a perhydrogermane having a SiH ₂ or GeH ₂ structure by a halogenation reaction and a reduction reaction using a hydride source such as LiAlH _4. It is characterized by film formation of Si, Ge, etc. by heating or laser irradiation using a composition obtained by conversion and mixing of these and their polymers as a precursor. In terms of using perhydrosilane or perhydrogermane having no organic substituent and having a SiH ₂ or GeH ₂ structure, the same characteristics as the previously reported techniques (for example, see Patent Document 3 and Non-Patent Document 10) Has become.

These film forming steps have to be performed in an inert gas atmosphere due to the extremely high reactivity of the compound having a SiH ₂ structure with oxygen in the air and the risk of ignition.

Even in the coating type film forming process, in order to avoid the high reactivity of oxygen and water in the air with the SiH ₂ structure, oxygen and water must be removed strictly in all processes. It has been pointed out that there is a film-forming process by an existing vapor phase method using silane gas as a raw material and a manufacturing method that is not different (for example, see Non-Patent Document 11). Even in the coating method, handling a compound having a SiH ₂ group that is very reactive with oxygen is a drawback from the viewpoint of reducing the apparatus cost and the process cost. The same applies to polygermane having a GeH ₂ structure.

  In the spread of solar cells, in addition to cost reduction, improvement of conversion efficiency is also an issue. In terms of increasing the efficiency of silicon-based solar cells, the development of tandem solar cells using germanium, which has absorption in the infrared region on the lower energy side than silicon, and SiGe, which is an alloy of silicon and germanium, is more advanced than silicon. It is performed for the purpose of efficiently absorbing light energy and converting it into electric energy with high efficiency (see, for example, Non-Patent Document 12).

Si _1-x Ge _x is a fully-solid-solution mixed crystal semiconductor in which the band gap can be continuously controlled from Ge to Ge by the Ge composition x. Since it is completely dissolved in a solid state and does not form an intermediate phase, it is a useful substance as a mixed crystal semiconductor material capable of band engineering (see, for example, Non-Patent Documents 13 and 14). That is, the presence of germanium in the silicon semiconductor film not only impairs the characteristics of the silicon semiconductor film but also works advantageously as a solar cell material.

  On the other hand, a technology for obtaining dispersibility and film-forming properties by forming a Si—O—Si covalent bond on the surface of the silicon fine particle by a chemical reaction between the surface of the silicon nanoparticle and the silicon alkoxide group. Documents 2 and 4), and further, a reactive epoxy group is introduced, a composition of this and a crosslinking agent such as a compound having an amino group is prepared, and a film forming property is obtained by the curing reaction (for example, However, in these techniques, Si—O—Si bonds and insulating resins that significantly affect the electrical properties of the Si semiconductor film are formed on the surface of the silicon fine particles. There have been no reports on the electrical characteristics of silicon films formed by these techniques.

  Regarding the formation of the SiGe alloy by the coating type process, the present inventor has made a prior technical report (for example, see Patent Document 7 and Non-Patent Document 8). A nanocluster-type germanium resin whose main chain skeleton is composed of a three-dimensional Ge—Ge bond and has an organic substituent in the side chain is applied to a silicon crystal substrate and heated at 700 ° C. or higher in a vacuum using an electric furnace. It has been reported that a SiGe alloy thin film can be formed on a silicon crystal substrate by processing.

  Regarding the formation of a coating-type SiGe alloy film, a technique using Si and Ge nanoparticles having an average particle size not exceeding 500 nm (for example, see Patent Document 2), and a composition of linear and crosslinked polysilane and polygermane are used. Although techniques to be used (see, for example, Patent Document 8) have been reported in later years, the structure and physical properties of semiconductor films formed by these techniques are unclear.

US Pat. No. 7,521,340 Special table 2010-514585 gazette JP 2004-087546 A JP 2007-173516 A Japanese Patent Laid-Open No. 08-0172626 Japanese Patent Laid-Open No. 11-14841 JP 2002-110573 A Special table 2009-511670 gazette

Akira Terakawa, “Toward Industrialization of Thin Film Silicon Solar Cells by Plasma CVD”, J. Plasma Fusion Res., 2010, Vol.86, No.1, p.17-20 Satoshi Sakai, Kenji Kono, “Stacked Organic Thin Film Solar Cell by Coating Method”, Panasonic Electric Works Technical Report, Vol.57, No.1, p.46-50 Supervised by Takahiro Wada, “Latest Technology of Compound Thin Film Solar Cell”, CMC, June 2007 “InnovalightEstablishes New Record with Silicon Ink, Solar Cells, Solar cells achieve 19percent conversion efficiency of sunlight to electricity”, 27 April 2010, INNOVALIGHT PRESS RELEASE, Internet <URL: http://www.innovalight.com/press_releases/ pressrelease_04272010.htm> A. Watanabe and M. Matsuda, “Electrical and Optical Properties of Heat-treated Silicon Network Polymers”, Chem. Lett., 1991, p. 1101-1104 A. Watanabe, Y. Nagai, M. Matsuda, M. Suezawa, and K. Sumino, “Amorphous Silicon Structure of Heat-Treated Poly (n-propylsilyne) Studied by Far-Infrared Spectroscopy”, Chem. Phys. Lett., 1993 Year, 207, p.132-136 A. Watanabe, M. Fujitsuka, O.Ito, and T. Miwa, “Soluble Three-Dimensional Polysilanes with Organosilicon Nanocluster Structure”, Jpn. J. Appl. Phys., 1997, 36, p.L1265-L1267 A. Watanabe, M. Unno, F. Hojo, and T. Miwa, “Silicon-Germanium Alloys Prepared by the Heat Treatment of Silicon Substrate Spin-Coated with Organo-Soluble Germanium Cluster”, Matterials Letters, 2001, 47, p. 89-94 A. Watanabe, M. Unno, F. Hojo, T. Miwa, “Spatially Selective Formation of Microcrystalline Germanium by Laser-Induced Pyrolysis of Organogermanium nanocluster Film”, Chem. Lett., 2002, p.662-663 T. Shimoda, Y. Matsuki, M. Furusawa, T. Aoki, I. Yudasaka, H. Tanaka, H. Iwasawa, D. Wang, M. Miyasaka, and Y. a Takeuchi, “Solution-processed silicon films and transistors” , 2006, Nature, 440 (6), p.783 L. Rosenberg, “Spray-on silicon”, Nature, News & Reviews, 2006, 440 (6), p.749 Katsuhiko Nomoto, Hiroshi Taniguchi, Hitoshi Sannomiya, Naoshi Hayakawa, “Device Design of Thin Film Solar Cells”, Sharp Technical Report No. 70, April 1998, p.40-43 Furukawa, Shizujiro, edited by Yoshihito Amemiya, “Silicon hetero devices”, Maruzen, 1991 Takayoshi Shimura, Michihiro Shimi, Shinichiro Horiuchi, Heiji Watanabe, Kiyoshi Yasutake, and Masataka Umeno, “Self-limiting oxidation of SiGe alloy on silicon-on-insulator wafers”, Appl. Phys. Lett. 2006, 89, p.111923

  As described above, regarding the energy environment problem, it is significant that a silicon-based coated solar cell is realized, and it is expected that technological development will progress worldwide in the future.

  For the purpose of solving the above-mentioned problems, the present inventor has worked for many years on technological development of semiconductor film formation using a coating-type silicon resin, but until now, it has not been realized. From the accumulation of research so far, it has been found that this is due to the following.

In silicon resins, the Si—Si skeleton is a molecule having a size of several nanometers regardless of whether it is linear, crosslinked, or three-dimensional. Thus, it has a very large surface area per weight as compared with the inorganic fine particles of Si. For this reason, it has a structure in which an easily oxidized structure is easily formed by an oxidizing gas such as air. In the case of a molecule or polymer having a SiH ₂ structure, the reactivity is higher and the ignition property in air is exhibited. When a silicon material of several nanometer size is formed by a coating method and converted to a film composed of a silicon continuous phase by heating or electromagnetic wave irradiation, a high-quality semiconductor film is obtained that is a substance having a very large surface area. It becomes a problem. Therefore, in the above-described prior art documents, all of the steps of raw material synthesis, film formation, and semiconductor film formation by heating and laser irradiation are performed in an inert gas atmosphere.

  In manufacturing processes where raw materials cannot be handled in the air and film formation is not possible, even if it is a liquid-phase coating-type film formation process, it is manufactured compared to the existing thin film formation method using plasma CVD using silane gas. Cost and process cost advantages are reduced.

  Such a problem of oxidative degradation of a silicon material having a surface structure with a large area is the same for Si nanoparticles. The surface area per weight is very large, and it is a substance with the risk of oxidative degradation and ignition in air. For this reason, like the above-mentioned prior art document, basically, handling in an inert gas atmosphere is required.

  From the above, using a silicon particle with a smaller surface area, that is, a silicon particle having a larger particle diameter, there is less problem of oxidative degradation, and a coating-type film forming process that can be handled in the air. It will be easy to realize. Silicon nanoparticles of micrometer size are more advantageous for the purpose than Si nanoparticles and Si nanoparticles rather than molecules and resins. The ratio of the total surface area of particles having particle diameters of 1 nanometer, 100 nanometers, and 10 micrometers is 10000: 100: 1. From now on, it is considered that the larger the particle diameter, the less susceptible to oxidative degradation. .

  However, when micrometer-sized silicon fine particles are used, several problems arise. One is the film-formability of micrometer-sized silicon fine particles. In forming a silicon semiconductor precursor film, it is necessary to uniformly disperse silicon fine particles in a solvent and apply it. Silicon nanoparticles with a small particle size can obtain better film-forming properties, but as in the prior art document mentioned above, in order to improve the dispersibility and film-forming property, the surface of the silicon nanoparticles Surface modifiers such as organosilicon alkoxides that form covalent bonds such as Si-O-Si bonds may be added.

Another technique for producing a coating film using silicon fine particles of micrometer size is a technique using cyclopentasilane as a dispersion medium, in which a SiH ₂ structure is linked in a ring, and is reported in the above-mentioned prior art document. Has been. In the case of this technique, the characteristic that cyclopentasilane is converted into inorganic Si by heating or laser irradiation is utilized, and the conductivity of a silicon film formed from silicon fine particles has been confirmed.

However, cyclopentasilane with a continuous SiH ₂ structure in a ring is a highly ignitable and ignitable compound in the air, and the handling and film forming process of cyclopentasilane must be performed in an inert gas atmosphere. is there. The problem with this is that, as with other known technologies, advantages in terms of manufacturing cost and process cost are reduced as compared with a thin film forming method using a plasma CVD method using an existing silane gas.

  Problems that arise when micrometer-sized silicon fine particles are used further include melting and binding of silicon fine particles, and the formation of a continuous silicon phase. The melting point of silicon is very high, 1410 ° C. Even in the case of micrometer-sized silicon fine particles, the silicon fine particles can be melted depending on the laser light irradiation conditions, but it is difficult to form a uniform film composed of a continuous phase of silicon.

  Summarizing the above technical problems, it is necessary to satisfy the following requirements in order to enable the handling and film forming process in the air and to solve the problem of forming a homogeneous silicon semiconductor film.

  As the size of the silicon fine particles, it is necessary to be a technology capable of using silicon fine particles having a micrometer size without causing problems of oxidative degradation and ignition in air.

  A homogeneous precursor film can be formed even in a coating-type film forming process using micrometer-sized silicon fine particles. For this purpose, a resin or a solvent as an organic dispersion medium is required, but they do not form an insulating structure such as a Si—O—Si structure by chemically bonding to the surface of the silicon fine particles. Also, do not form an insulating resin structure between silicon particles. Furthermore, these resins and solvents must be able to be handled stably in the air.

  In the formation of a homogeneous precursor film using micrometer-sized silicon fine particles, it is also a requirement that the resin to be added is caking and that adhesiveness can be imparted between the silicon fine particles. For this purpose, a resin having a glass transition temperature of room temperature or lower is preferable.

  A uniform Si-based semiconductor film can be formed by heating micrometer-sized silicon particles or laser irradiation. For this purpose, the resin covering the surface of the Si fine particles promotes the melting of Si, and as a result, it is possible to form a silicon continuous phase by melting and binding the silicon fine particles at a temperature lower than the melting point of Si. That is, it is necessary that the resin to be added serves as a fusing agent for silicon fine particles and does not interfere with the characteristics of silicon as a semiconductor.

  As described above, an object of the present invention is to provide a silicon-germanium film and a method for manufacturing the silicon-germanium film, which can be formed in air and have a low manufacturing process cost.

  According to the present invention, a composition film formed from a dispersion obtained by mixing a germanium resin having an organic substituent in a side chain and silicon fine particles having an average particle diameter of 1 μm or more in an organic dispersion medium is subjected to heat treatment or A silicon-germanium film characterized by being obtained by laser irradiation is obtained.

  Further, according to the present invention, the main chain skeleton synthesized using germanium tetrachloride as a starting material is composed of a three-dimensional Ge—Ge bond, and the germanium resin having an organic substituent in the side chain covers the surface of the silicon particle. The silicon-germanium is characterized in that the germanium resin and the silicon particles are mixed and pulverized, a composition obtained by mixing the mixed pulverized material in an organic dispersion medium is formed into a film, and then heat treatment or laser irradiation is performed. A film manufacturing method is obtained.

  Further, according to the present invention, there is obtained a method for producing a silicon-germanium film, wherein the germanium resin has a glass transition temperature of room temperature or lower.

  According to the present invention, the silicon-germanium film is characterized in that the composition obtained by mixing the germanium resin and the silicon fine particles in an organic dispersion medium is applied to a substrate in the air to form a film. The manufacturing method is obtained.

  Further, according to the present invention, the organic substituent of the germanium resin on the surface of the silicon fine particles coated with the germanium resin is removed by heating or laser irradiation, and inorganic germanium and silicon are alloyed. A method for producing a silicon-germanium film is obtained.

Furthermore, according to the present invention, there can be obtained a method for producing a silicon-germanium film characterized in that, in the laser irradiation step, a portion which is not affected by the heat of the laser is washed away with an organic solvent.
Hereinafter, the present invention will be described in detail.

  In the present invention, the germanium resin used as a dispersion medium and as a fusing agent for silicon fine particles is a substance that the inventor has reported for the first time as shown in the above-mentioned prior art document. Is a nanocluster-type germanium resin whose main chain skeleton is composed of a three-dimensional Ge—Ge bond and has an organic substituent in the side chain.

  This germanium resin has four-coordinate Ge atoms having four Ge—Ge bonds, and three-coordinate Ge atoms having three Ge—Ge bonds. It is suitable as a dispersion medium for converting to Silicon resin consisting of Si-Si bonds and germanium resin consisting of Ge-Ge bonds generate more volatile decomposition products due to thermal decomposition than tetra- or tri-coordinate branched structures with linear or cyclic structures. It has been shown in the above-mentioned prior art documents that the amount of residual inorganic components after firing is remarkably increased by suppressing the above.

  In the present invention, a germanium resin having a structure in which the Ge—Ge skeleton is substituted with an organic group is used as a dispersion medium. The inventor has reported that such a germanium resin can be converted into inorganic germanium by heating or laser irradiation without residual carbon. This is due to the fact that the Ge—C bond is unstable compared to the strong covalent bond Si—C bond.

  The germanium resin used in this study can be handled stably in the air, but even if a part of the structure is oxidized, the germanium oxide structure can be removed by laser irradiation. This is because the Ge—O—Ge bond is unstable compared to the Si—O—Si bond.

  The germanium resin used in this study is characterized in that when the organic side chain is a linear alkyl group having 4 or more carbon atoms, it is a viscous liquid at room temperature.

  The characteristics of the above germanium resin are suitable as a dispersion medium for silicon fine particles having a micrometer size. By coating the surface of the silicon fine particles with a germanium resin having high stability in the air as a dispersion medium and making the dispersion state, oxidative deterioration of the surface of the silicon fine particles can be suppressed.

  The silicon fine particle germanium resin composition is prepared by mixing and crushing a germanium resin and polycrystalline or single crystal silicon in air or in an inert gas atmosphere. In the pulverization, various aliphatic and aromatic solvents can be added in order to effectively mix the germanium resin and the silicon fine particles formed by the pulverization.

  As a raw material of silicon fine particles formed by pulverization at the time of mixing with a germanium resin used in the preparation of the above composition, polycrystalline or single crystal silicon, undoped or doped, can be used. However, there is no particular limitation as long as the object and effect of the present invention are not impaired.

  The silicon fine particle germanium resin composition is stable in the air, and can be formed without the need for a special apparatus for controlling the film forming atmosphere. Such characteristics are suitable for manufacturing a large area solar cell at low cost.

  Such handling in air is possible because of the structure in which silicon microparticles of micrometer size are coated with germanium resin that is stable in air, and a part of the structure of germanium resin is oxidized. This is because the Ge—O—Ge structure can be removed by laser irradiation.

  The raw material of the silicon fine particles can be polycrystalline or single crystal silicon, which can be undoped or doped, and does not require a special device for producing silicon nanoparticles. Since the doping process can be omitted, it is effective in reducing the manufacturing cost. Also, in comparison with the conventional method for manufacturing a crystalline silicon solar cell, it is possible to reduce the cost of pulling up the single crystal silicon ingot and processing the Si wafer, and further, it is possible to form a solar cell with resource saving by thinning. There are advantages.

  As a further feature of using germanium resin as a dispersion medium and a fusing agent, there is an effect that the temperature at which Si fine particles are melted and bound can be lowered by forming a SiGe alloy. A germanium resin thin film formed by spin coating on a silicon single crystal substrate is subjected to SiGe alloy thin film formation at a temperature lower than the melting point of silicon, 1410 ° C., by 600 ° C. or more with melting of the Si substrate surface. The present inventor has discovered in advance and reported in the above-mentioned prior art documents.

  The germanium resin having such characteristics is used as a fusing agent for silicon fine particles in a precursor film of a composition composed of micrometer-sized silicon fine particles, which lowers the melting point of the silicon fine particles and binds the silicon fine particles. The use of this has led to the idea that the problem in forming a coating-type silicon semiconductor film can be solved.

  In laser irradiation of the silicon fine particle germanium resin composition, germanium resin is converted into inorganic germanium, silicon fine particles are melted, and a SiGe alloy is formed. In contrast, when the laser is not irradiated, the silicon fine particle germanium resin composition retains dispersibility in the solvent due to the solvent solubility of the germanium resin. Thus, the present invention has a feature that a fine pattern of a crystalline semiconductor film can be formed.

  According to the present invention, it is possible to provide a silicon-germanium film and a method for producing a silicon-germanium film, which can be formed in air and have a low manufacturing process cost.

  The semiconductor film manufacturing method and semiconductor film pattern forming method using silicon fine particles as a raw material according to the present invention is a technique capable of forming a film in the atmosphere by a coating method, and requires a high-cost manufacturing apparatus required by the conventional method. However, it is possible to provide a method suitable for reducing the manufacturing cost, which is a problem in the spread of solar cells. In addition, due to the solvent dispersibility of the silicon fine particle germanium resin composition, in laser irradiation, a fine pattern of a semiconductor film can be formed by washing and removing with an organic solvent in a laser non-irradiated portion, such as conventional photolithography Thus, it is possible to provide a method suitable for simplifying the microfabrication process. The semiconductor film formation and crystalline semiconductor film and their pattern formation methods according to the present invention can be applied to various optoelectronic devices in addition to the semiconductor film for solar cells. For example, it can be used for a thin film transistor, a phototransistor, and the like.

It is a schematic diagram which shows the apparatus and optical system for performing laser irradiation and pattern formation of the manufacturing method of the silicon- germanium film | membrane and silicon- germanium film | membrane of embodiment of this invention. FIG. 4 is a confocal laser micrograph of (a) a silicon fine particle germanium resin composition film and (b) a silicon fine particle coating film of the silicon-germanium film and the silicon-germanium film manufacturing method of the embodiment of the present invention. is there. It is a confocal laser scanning micrograph of the composition film | membrane of the silicon nanoparticle with an average particle diameter of 50 nm, and a germanium resin as a comparative example of the manufacturing method of the silicon- germanium film | membrane and silicon- germanium film | membrane of embodiment of this invention. It is a schematic diagram which shows the structural change which arises by baking and laser irradiation of the silicon fine particle germanium resin composition precursor film | membrane of the manufacturing method of the silicon- germanium film | membrane and silicon- germanium film | membrane of embodiment of this invention. (A) Confocal of a sample prepared by performing laser irradiation in air using a silicon fine particle germanium resin composition film in the method for producing a silicon-germanium film and a silicon-germanium film according to an embodiment of the present invention. It is a graph which shows a microscope picture, (b) three-dimensional figure, and (c) film | membrane sectional drawing. (A) A sample prepared by performing laser irradiation in an Ar atmosphere using the silicon fine particle germanium resin composition film of the silicon-germanium film and the silicon-germanium film manufacturing method of the embodiment of the present invention. It is a graph which shows a focus microscope picture, (b) three-dimensional figure, and (c) film | membrane sectional drawing. As a comparative example of the silicon-germanium film and the silicon-germanium film manufacturing method according to the embodiment of the present invention, laser irradiation is performed in an Ar atmosphere using a coating film of silicon fine particles to which no germanium resin is added. It is a graph which shows (a) a confocal microscope picture, (b) three-dimensional figure, and (c) film | membrane sectional drawing of the produced sample. As a comparative example of the silicon-germanium film and the silicon-germanium film manufacturing method of the embodiment of the present invention, laser irradiation is performed in an Ar atmosphere using a silicon nanoparticle germanium resin composition film having an average particle diameter of 50 nm. 5A is a graph showing (a) a confocal micrograph, (b) a three-dimensional view, and (c) a film cross-sectional view of the sample prepared in the above. (A) A sample prepared by performing laser irradiation in an Ar atmosphere using the silicon fine particle germanium resin composition film of the silicon-germanium film and the silicon-germanium film manufacturing method of the embodiment of the present invention. It is a graph which shows a focus microscope picture, (b) three-dimensional figure, and (c) film | membrane sectional drawing. It is a graph which shows the microscopic Raman spectrum of the laser irradiation film | membrane pattern in the air of the silicon fine particle germanium resin composition of the manufacturing method of the silicon- germanium film | membrane and silicon- germanium film | membrane of embodiment of this invention. (A) Point I in FIG. 6 of a laser-irradiated film pattern in an Ar atmosphere of a silicon fine particle germanium resin composition in the method for producing a silicon-germanium film and a silicon-germanium film according to an embodiment of the present invention (B) It is a graph which shows the micro Raman spectrum in the point of II in FIG. (A) Point I in FIG. 9 of a laser-irradiated film pattern in an Ar atmosphere of a silicon fine particle germanium resin composition in the method for producing a silicon-germanium film and a silicon-germanium film according to an embodiment of the present invention (B) It is a graph which shows the micro Raman spectrum in the point of II in FIG. 9, and (c) the point of III in FIG. The silicon fine particle germanium resin composition of the silicon-germanium film and the silicon-germanium film manufacturing method of the embodiment of the present invention, (a) a film before firing, (b) a film fired at 250 ° C. in an electric furnace under vacuum, (C) It is a graph which shows the micro Raman spectrum of the film | membrane which baked at 900 degreeC electric furnace under vacuum. (A) a confocal micrograph of a laser irradiation film pattern in an Ar atmosphere of a silicon fine particle germanium resin composition in the method for producing a silicon-germanium film and a silicon-germanium film according to an embodiment of the present invention; (b) It is a graph which shows the current-voltage characteristic of the film | membrane pattern. Current-voltage characteristics of laser-irradiated film pattern under Ar irradiation of silicon fine particle germanium resin composition of silicon-germanium film and silicon-germanium film manufacturing method of embodiment of the present invention It is a graph which shows.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
In the present invention, a composition of micrometer-sized silicon fine particles and a germanium resin as a dispersion medium and a fusing agent is coated on a solid substrate, and the film is used as a precursor, by heating or laser irradiation, The essence is to perform semiconductor film formation and crystalline semiconductor film and pattern formation thereof.

  The germanium resin used in the present invention is preferably a nanocluster type resin synthesized from germanium tetrachloride as a raw material, the main chain skeleton consisting of a three-dimensional Ge—Ge bond, and having an organic substituent in the side chain. However, as long as it can be converted into inorganic germanium by heating, it is not limited thereto.

  In a nanocluster type resin synthesized using germanium tetrachloride as a raw material and having a main chain skeleton consisting of a three-dimensional Ge-Ge bond and having an organic substituent in the side chain, examples of the organic substituent include linear saturation Examples include an aliphatic group, a branched saturated aliphatic group, a linear unsaturated aliphatic group, a branched unsaturated aliphatic group, or an aromatic group. The property of the germanium resin to be synthesized is affected by the organic substituent, and in the case of a linear saturated aliphatic group having 4 or more carbon atoms, it is liquid, and the viscosity tends to decrease as the chain length increases. . In the case of a branched saturated aliphatic group, for example, in the case of a tert-butyl group, it becomes a glassy solid at room temperature. As a dispersion medium for silicon fine particles, a high-viscosity liquid having a linear saturated aliphatic group is preferable in terms of the film forming property of the precursor film. It depends on the composition ratio and is not limited thereto.

  The silicon fine particle germanium resin composition is prepared by mixing and crushing a germanium resin and polycrystalline or single crystal silicon in air or in an inert gas atmosphere. In the pulverization, an aliphatic or aromatic solvent can be added as an organic dispersion medium in order to effectively mix the germanium resin and the silicon fine particles formed by the pulverization.

  In the present invention, as a raw material for micrometer-sized silicon fine particles, polycrystalline or single crystal silicon, undoped or doped, can be used. This is effective in reducing the manufacturing cost because it does not require a special device as in the case of Si nanoparticles. Also, in comparison with the conventional method for manufacturing a crystalline silicon solar cell, it is possible to reduce the cost of pulling up the single crystal silicon ingot and processing the Si wafer, and further, it is possible to form a solar cell with resource saving by thinning. There are advantages.

  In the present invention, spin coating, doctor blade, screen printing, spray coating, dip coating, and the like can be used as a method for forming the silicon fine particle germanium resin composition, but the method is not limited thereto. It is not something.

  The laser light source that can be used for laser irradiation in the present invention is appropriately selected in consideration of the wavelength to be irradiated and the power density. Specific examples include a continuous wave (CW) diode pumped solid state (DPSS) laser having an oscillation wavelength of 457, 473, 488, 532, 561, 660, or 1064 nm, a pulsed laser, 266, 355, 532, Alternatively, those having an oscillation wavelength of 1064 nm, He-Cd lasers having an oscillation wavelength of 325 and 442 nm, Ar ion lasers having an oscillation wavelength of 488 and 514.5 nm, titanium sapphire lasers having an oscillation wavelength of 800 nm, 408, 442, Semiconductor lasers having an oscillation wavelength of 473, 638, 658, 780, or 830 nm, excimer lasers having an oscillation wavelength of 193, 248, 308, or 353 nm, fiber lasers having an oscillation wavelength from the ultraviolet region to the infrared region, etc. But it is lower, but is not limited thereto.

  In the embodiment of the present invention, a CW DPSS laser having an oscillation wavelength of 532 nm is used. However, since the power is as small as 1 W, a high-power objective lens is used until the spot size becomes several microns. After irradiation, the precursor film is focused and laser light is scanned on the precursor film to perform laser irradiation and pattern formation. From the viewpoint of increasing industrial productivity for large-area solar cells, etc., pulsed lasers such as excimer lasers that have been put to practical use for laser annealing of silicon semiconductor materials, and high-power fiber lasers. Is preferably applied.

  In the present invention, a fine pattern of a crystalline semiconductor film can be formed by utilizing solvent dispersibility without laser irradiation in laser irradiation. For removal without irradiation with laser, ultrasonic irradiation for several seconds is effective for solvent cleaning or when removal is difficult.

The present invention will be described more specifically with reference to examples. However, the present invention is not limited to the following preparation examples and examples. The experimental apparatus used in the examples is as follows.
[Optical microscope]
・ Model: Olympus BX51
Objective lenses: SLMPlan 20x (NA 0.35), SLMPlan 50x (NA 0.45), UMMPlan 100x (NA 0.95)
[CCD camera]
・ Model: Waitec, WAT231S2
[Xyz automatic stage]
・ Models: Sigma Koki Co., Ltd., TSDM60-20, SPSD60-10ZF
[Stage controller]
・ Model: Sigma Koki Co., SHOT-204MS
[Electromagnetic shutter]
・ Model: Sigma Koki Co., SSH-R
[Shutter controller]
・ Model: Sigma Koki Co., SSH-CB4
[Continuous oscillation (CW) diode pumped solid (DPSS) laser light source]
・ Model 2: CNI, MGL-H-532-1W (532 nm, 1.18 W, TEM ₀₀ mode)
[Micro Raman spectroscopy]
Laser light source: continuous wave (CW) diode pumped solid (DPSS) laser, Laser Quantum, Ventus 532 (532 nm, 500 mW)
Spectrometer: ORIEL, 77385
・ Cooling CCD camera: Apogee, AP260EP
[Three-dimensional (3D) confocal laser microscope]
・ Model: Keyence Corporation, color 3D laser microscope VK-9700
[light source]
・ Model: Mercury Xenon lamp (C4263 from Hamamatsu Photonics)
[DC voltage / current source / monitor]
・ Model: ADMT, 6241A

<Synthesis example 1 of germanium resin>
A synthesis example of a germanium resin having a tert-butyl group is shown.
Magnesium tetrachloride (6.83 g) was added to magnesium (6.22 g) with stirring in dehydrated tetrahydrofuran (80 ml) under an argon atmosphere, and reacted at 10 ° C. with stirring for 1 hour. Thereby, a germanium cluster having a size of several nanometers is formed by the Grignard reaction of germanium tetrachloride. The germanium nanocluster dispersed in tetrahydrofuran as a solvent has an unreacted chlorine group on the surface. By replacing this chlorine group with an organic substituent, it is soluble in a general-purpose organic solvent, and air A nanocluster type germanium resin having a main chain skeleton composed of a three-dimensional Ge—Ge bond and having an organic substituent in a side chain, which can be handled stably in the inside, was synthesized. The synthesis was performed according to the following procedure. First, tert-butyl bromide (4.38 g) was added and reacted with stirring at 10 ° C. for 1 hour, tert-butyl bromide (4.38 g) was added again, 10 ° C. for 1 hour, and 50 ° C. for 2 hours. The reaction was allowed to stir for an hour. Thereafter, the reaction was carried out at room temperature with stirring all day and night. The reaction solution was precipitated in methanol and separated by filtration. A polymer was obtained by reprecipitation. Further, the polymer was dissolved in toluene, insoluble components were separated and removed, and then purified polymer was obtained by removing toluene under reduced pressure. When the molecular weight of this polymer was measured by GPC, it was weight average molecular weight Mw = 1800 and molecular weight distribution Mw / Mn = 1.63. From the elemental analysis, the number of organic substituents per Ge atom was 0.8. This resin was a black glassy solid powder at room temperature.

<Synthesis example 2 of germanium resin>
A synthesis example of a germanium resin having an n-butyl group is shown.
Magnesium tetrachloride (25 g) was added to magnesium (8.5 g) with stirring in dehydrated tetrahydrofuran (200 ml) under an argon atmosphere and reacted at 10 ° C. with stirring for 1 hour. Thereby, a germanium cluster having a size of several nanometers is formed by the Grignard reaction of germanium tetrachloride. The germanium nanocluster dispersed in tetrahydrofuran as a solvent has an unreacted chlorine group on the surface. By replacing this chlorine group with an organic substituent, it is soluble in a general-purpose organic solvent, and air A nanocluster type germanium resin having a main chain skeleton composed of a three-dimensional Ge—Ge bond and having an organic substituent in a side chain, which can be handled stably in the inside, was synthesized. The synthesis was performed according to the following procedure. First, n-butyl bromide (16 g) was added and reacted with stirring at 10 ° C. for 1 hour, and n-butyl bromide (16 g) was added again and stirred at 10 ° C. for 1 hour and at 50 ° C. for 2 hours with stirring. Reacted. Thereafter, the reaction was carried out at room temperature with stirring all day and night. The reaction solution was precipitated in methanol and separated by filtration. A polymer was obtained by reprecipitation. Further, the polymer was dissolved in toluene, insoluble components were separated and removed, and then purified polymer was obtained by removing toluene under reduced pressure. When the molecular weight of this polymer was measured by GPC, it was weight average molecular weight Mw = 3600 and molecular weight distribution Mw / Mn = 1.30. From the elemental analysis, the number of organic substituents per Ge atom was 1.2. This resin was a black viscous liquid at room temperature. This polymer was used in the following experiment as a germanium resin for dispersing silicon fine particles.

  FIG. 1 is a schematic diagram of a laser beam irradiation / scanning apparatus and an optical system for performing laser irradiation of a semiconductor film manufacturing method and a semiconductor film pattern using silicon fine particles as a raw material according to an embodiment of the present invention. As the laser light source, a continuous wave (CW) diode-excited solid (DPSS) laser was used. The laser beam introduced into the optical microscope 11 is condensed by the objective lens 12 and irradiated so as to be focused on the substrate 15 on which the precursor coating film is formed. The semiconductor film pattern is drawn by scanning the irradiation position of the laser beam on the substrate 15 with the xyz stage 17 controlled by the computer 16 and the stage controller 21. The laser light is turned on and off by an electromagnetic shutter 18 controlled by a computer 16 and a shutter controller 20. The semiconductor film pattern formed on the substrate 15 was observed by the CCD camera 19 connected to the optical microscope 11. By introducing an inert gas or Ar gas-diluted hydrogen gas from the gas introduction tube 14 into the objective lens cover 13, the laser light irradiation atmosphere can be easily controlled.

  After treating 0.4 g of n-type silicon crystal (<100>, dopant: Ph, resistivity 2 Ωcm) with dilute hydrofluoric acid aqueous solution (5%) to remove surface oxides, germanium resin 0 as a dispersion medium 0.1 g (20 wt% with respect to silicon) and a toluene solvent as an organic dispersion medium were pulverized and mixed in a mortar to prepare a silicon fine particle germanium resin composition under air. When the germanium resin is mineralized, in the case of a composition containing 20 wt% germanium resin, the weight ratio of Si and Ge is about 8: 1, and the element ratio of Si and Ge is 20: 1. By reducing the composition ratio of the germanium resin, it is possible to reduce the change in characteristics of the obtained silicon film.

  A toluene dispersion of the silicon fine particle germanium resin composition was dropped on a glass substrate as a substrate, and a precursor film was formed under air by a doctor blade method. The amount of toluene as the organic dispersion medium for the silicon fine particle germanium resin composition was appropriately adjusted according to the thickness of the film formed by the doctor blade method. The silicon fine particle germanium resin composition film was used as a precursor film for heat treatment and laser irradiation after drying and removing toluene as a solvent.

  As a comparative sample of a precursor film prepared from a toluene dispersion of a silicon fine particle germanium resin composition, n-type silicon is pulverized in a mortar together with a toluene dispersion medium, a glass substrate is used as a substrate, and the resultant is dropped on the glass substrate and dried. As a result, a coating film containing no germanium resin was prepared. This coating film was easily peeled off with a slight impact on the coating film substrate because there was no resin that covered and adhered silicon fine particles.

  2A and 2B show confocal laser micrographs of the silicon fine particle germanium resin composition film and the silicon fine particle coating film, respectively. From the photograph of the silicon fine particle coating film shown in FIG. 2 (b), it is found that silicon fine particles having a micrometer size having a size distribution of several μm to several tens of μm are formed by the above-described pulverization method. Indicated. On the other hand, in the photograph of the silicon fine particle germanium resin composition film shown in FIG. 2A, silicon fine particles having a size of about 10 μm as seen in FIG. 2B were not observed. This is because the surface of the silicon fine particles is uniformly covered with black and highly viscous germanium resin.

[Comparative Example 1]
As a comparative sample, a composition film of silicon nanopowder (Aldrich, crystalline silicon nanoparticles produced by laser pyrolysis) having an average particle diameter of 50 nm and germanium resin was formed. 0.4 g of Si nanoparticles are mixed in an Ar atmosphere together with 0.1 g of germanium resin (20 wt% relative to silicon) as a dispersion medium and a toluene solvent as an organic dispersion medium, and sealed in a sample tube. A silicon nanoparticle germanium resin composition was prepared by irradiation. A toluene solution of the silicon nanoparticle germanium resin composition was dropped on a glass substrate as a substrate, and a film was formed by a doctor blade method. FIG. 3 is a confocal laser micrograph of the silicon nanoparticle germanium resin composition film. As shown in the photograph, in the silicon nanoparticle germanium resin composition film, it was observed that cracking occurred in the film with the volatilization of toluene. This is because 20 wt% germanium resin with respect to Si cannot sufficiently cover the surface of the silicon nanoparticles and impart adhesiveness between the silicon nanoparticles.

  Therefore, a composition in which 200 wt% germanium resin was added to Si was prepared, and similar film formation and confocal laser microscope observation were performed. However, cracks were also observed in the coating film. From these results, silicon nanoparticles have a very large surface area compared to micrometer-sized silicon fine particles, and a large amount of resin is required to obtain a uniform coating film without cracks. It was shown that. In silicon nanoparticles, it is not preferable to add a large amount of resin to obtain a homogeneous silicon semiconductor film after firing.

  FIG. 4 shows the silicon fine particle germanium resin composition film of the embodiment of the present invention as a precursor, and the germanium resin acts as a fusing agent for the silicon fine particles by firing or laser light irradiation. It is a schematic diagram of a process in which a film is formed. In the state before firing or laser light irradiation in FIG. 4A, the germanium resin coats the Si fine particles without voids to form a Si fine particle germanium resin composition film. This is shown by the confocal laser micrograph of FIG. In the case of no germanium resin or a silicon nanoparticle germanium resin composition having an average particle size of 50 nm, as shown in the confocal laser micrographs of FIGS. 2 (b) and 3, respectively, As shown in a comparative example described below, the film after laser irradiation has a non-uniform structure. FIG. 4B is a structure formed when the heating temperature is relatively low so that SiGe alloying does not occur. This corresponds to, for example, the case of 250 ° C. heating using the electric furnace of Example 8 in the following examples. In this state, the germanium resin is converted to inorganic germanium, and this film is not removed by solvent washing. In contrast, in the state of FIG. 4A, the germanium resin is soluble in the solvent, and the composition film is removed by solvent washing. By utilizing such a difference in removability with respect to the solvent, pattern formation of the semiconductor film according to the embodiment of the present invention is achieved by laser irradiation and non-irradiation in laser irradiation. FIG. 4C shows a structure formed at a temperature at which SiGe alloying occurs, and the silicon fine particles are bound by the formation of the SiGe alloy between silicon and inorganic germanium on the silicon fine particle surface layer. As shown in FIG. 4D, as the further SiGe alloy formation proceeds, fusion occurs between the silicon fine particles, and a film composed of a silicon continuous phase is formed. From the following examples, it is shown that the fusing phenomenon of silicon fine particles by germanium resin occurs as schematically shown in FIG.

  Using the silicon fine particle germanium resin composition film prepared in Example 1, laser irradiation was performed in the air using the apparatus shown in FIG. Laser light irradiation conditions are: objective lens: x20 (NA 0.32), incident laser light power: 1 W, laser light scanning conditions: x: 4000 μm, y: 1000 μm, y-direction scanning line interval: 10 μm, scanning Speed: 4000 μm / s. After the laser beam irradiation, the silicon fine particle germanium resin composition film in the unirradiated part was removed using a toluene solvent.

  FIG. 5 is a measurement result of a 3D confocal laser microscope. 5A, 5B, and 5C are a confocal micrograph, a three-dimensional view, and a film cross-sectional view, respectively. In FIG. 5A, the upper part is the film surface of the silicon fine particle germanium resin composition irradiated with the laser beam, and the lower part is the glass substrate surface from which the unirradiated part is removed using a toluene solvent. The three-dimensional view of FIG. 5B shows a three-dimensional image of the laser irradiation film of the silicon fine particle germanium resin composition on the glass substrate. From the cross-sectional view of FIG. 5C, it can be seen that the film thickness is about 15 μm. 5 (b) and 5 (c), it was observed that the film surface was roughened in the laser irradiation film under air. In laser irradiation under air, thermal decomposition accompanied with oxidation reaction of germanium resin covering silicon fine particles occurred rapidly due to oxygen, which caused film surface roughness.

  Therefore, in the apparatus shown in FIG. 1, laser irradiation of the silicon fine particle germanium resin composition film was performed in an inert atmosphere by introducing Ar gas into the objective lens cover 13 from the gas introduction tube 14. Laser light irradiation conditions are: objective lens: x50 (NA 0.32), incident laser light power: 1 W, laser light scanning conditions: x: 4000 μm, y: 1000 μm, y-direction scanning line interval: 5 μm, scanning Speed: 4000 μm / s. After the laser beam irradiation, the silicon fine particle germanium resin composition film in the unirradiated part was removed using a toluene solvent.

  FIG. 6 is a measurement result of a film irradiated with a laser in an Ar atmosphere using a 3D confocal laser microscope. 6A, 6B, and 6C are a confocal micrograph, a three-dimensional view, and a film cross-sectional view, respectively. In FIG. 6A, the upper part is the film surface of the silicon fine particle germanium resin composition irradiated with the laser beam, and the lower part is the glass substrate surface from which the non-irradiated part is removed using a toluene solvent. The three-dimensional view of FIG. 6B shows a three-dimensional image of the laser irradiation film of the silicon fine particle germanium resin composition on the glass substrate. From the cross-sectional view of FIG. 6C, it can be seen that the film thickness is about 14 μm. As shown in FIG. 6A, the surface of the laser-irradiated film in the Ar atmosphere was smooth and smooth compared to that in the air. 6A and 6B show that silicon fine particles are not observed in the portion I, and are completely melted and bound to form a continuous phase of silicon. This state is schematically shown in FIG. 4D. This result shows that germanium resin acts effectively as a fusing agent for silicon fine particles.

  In FIG. 6 (a), the site indicated by I is a laser beam irradiated part, and the site indicated by II is a part that has not been removed by the toluene solvent treatment, although it is a laser non-irradiated part. . The white line visible at the boundary between I and II is the lowest end of the laser light irradiation. The reason why it remains without being removed is that firing has occurred due to heat transfer from the laser irradiation section. The state II is shown schematically in FIG. 4B.

[Comparative Example 2]
As a comparative example of the laser irradiation film, laser irradiation of the silicon fine particle coating film to which the germanium resin prepared in Example 1 was not added was performed in an Ar atmosphere by the apparatus shown in FIG. Laser light irradiation conditions are: objective lens: x50 (NA 0.32), incident laser light power: 1 W, laser light scanning conditions: x: 4000 μm, y: 1000 μm, y-direction scanning line interval: 5 μm, scanning Speed: 4000 μm / s. After the laser light irradiation, the silicon fine particles were removed from the unirradiated part by irradiating with ultrasonic waves for several seconds in a toluene solvent. FIG. 7 is a measurement result of a 3D confocal laser microscope of the laser irradiated film. 7A, 7B, and 7C are a confocal micrograph, a three-dimensional view, and a film cross-sectional view, respectively. In FIG. 7A, the upper part is the film surface of the silicon fine particle germanium resin composition irradiated with the laser beam, and the lower part is the glass substrate surface from which the non-irradiated part is removed using a toluene solvent. In the three-dimensional view of FIG. 7B, a three-dimensional image of a laser irradiation film of silicon fine particles on a glass substrate is shown. As shown in FIG. 7, in the absence of germanium resin, a film with a very non-uniform structure was formed, and a lump having a size of several tens of μm and an exposed glass substrate surface were observed. This is because the silicon fine particles melted by the laser irradiation aggregate with the silicon fine particles having fewer voids in the precursor film due to the surface tension to form a non-uniform particle-like structure. In contrast, in the case of the silicon fine particle germanium resin composition, as shown in FIGS. 4 and 5, a homogeneous continuous phase is formed by melting of the silicon fine particles. As schematically shown in FIG. 4, the germanium resin present between the silicon fine particles is converted into inorganic germanium with thermal decomposition by laser irradiation to form silicon fine particles and a SiGe alloy, which is a fusion agent. This is to form a continuous phase of silicon.

[Comparative Example 3]
As a comparative example of the laser irradiation film, laser irradiation of the silicon nanoparticle germanium resin composition film prepared in Comparative Example 1 was performed in an Ar atmosphere by the apparatus shown in FIG. Laser light irradiation conditions are: objective lens: x50 (NA 0.32), incident laser light power: 1 W, laser light scanning conditions: x: 4000 μm, y: 1000 μm, y-direction scanning line interval: 5 μm, scanning Speed: 4000 μm / s. After the laser light irradiation, the silicon nanoparticle germanium resin composition film in the unirradiated part in the toluene solvent was removed. FIG. 8 is a measurement result of a 3D confocal laser microscope of the film irradiated with the laser. 8A, 8B, and 8C are a confocal micrograph, a three-dimensional view, and a film cross-sectional view, respectively. In FIG. 8A, the upper part is the film surface of the silicon fine particle germanium resin composition irradiated with the laser beam, and the lower part is the glass substrate surface from which the non-irradiated part is removed using a toluene solvent. In the three-dimensional view of FIG. 8B, a three-dimensional image of the laser irradiation film of the silicon nanoparticle germanium resin composition on the glass substrate is shown. As shown in FIG. 8, in the case of silicon nanoparticles, even if germanium resin is present, a film with a very non-uniform structure is formed, and a lump of a size of several tens of μm and an exposed glass substrate surface are formed. Observed. This is because the surface area of silicon nanoparticles is very large compared to silicon microparticles of micrometer size, and 20 wt% germanium resin used as a dispersion medium for Si covers the surface of silicon nanoparticles, This is because the binding property cannot be imparted between the silicon nanoparticles. For this reason, the silicon fine particles melted by the laser irradiation were aggregated by the surface tension, and a non-uniform grain structure was formed.

  Using the silicon fine particle germanium resin composition film produced in Example 1, laser irradiation was performed in an Ar atmosphere by the apparatus shown in FIG. Laser light irradiation conditions are: objective lens: x20 (NA 0.32), incident laser light power: 1 W, laser light scanning conditions: x: 4000 μm, y: 1000 μm, y-direction scanning line interval: 100 μm, scanning Speed: 400 μm / s. After the laser beam irradiation, the silicon fine particle germanium resin composition film in the unirradiated part was removed using a toluene solvent.

  FIG. 9 shows the measurement results of a 3D confocal laser microscope. FIGS. 9A, 9B, and 9C are a confocal micrograph, a three-dimensional view, and a film cross-sectional view, respectively. In FIG. 9A, the upper part is the film surface of the silicon fine particle germanium resin composition irradiated with the laser beam, and the lower part is the glass substrate surface from which the unirradiated part is removed using a toluene solvent. In the three-dimensional view of FIG. 9B, a three-dimensional image of the laser irradiation film of the silicon fine particle germanium resin composition on the glass substrate is shown.

  In FIG. 9 (a), the part indicated by I is a laser light irradiation part, and the part indicated by II and III is a laser non-irradiation part, but remains without being removed by the toluene solvent treatment. It is. The reason that the portions II and III remain without being removed even though the laser has not been irradiated is that firing by heat transfer from the laser irradiation portion has occurred. As demonstrated by structural analysis by microscopic Raman spectrum in Example 7 below, the site of II corresponds to the structure schematically shown in FIG. 4C, and the site of III is the structure schematically shown in FIG. 4B. Corresponding to

FIG. 10 is a microscopic Raman spectrum of the laser irradiation film pattern of the silicon fine particle germanium resin composition prepared in Example 2 under air. A sharp band of 520 cm ⁻¹ is attributed to polycrystalline silicon (pc-Si).

FIG. 11 is a microscopic Raman spectrum of the laser irradiation film pattern of the silicon fine particle germanium resin composition prepared in Example 2 under an Ar atmosphere. FIGS. 11A and 11B are microscopic Raman spectra at the sites I and II in FIG. 6, respectively. In FIG. 11A, a sharp band of 520 cm ⁻¹ is attributed to polycrystalline silicon (pc-Si). Amorphous silicon in the vicinity of 470 cm ^-1 in addition to (a-Si), Raman bands attributed to the polycrystalline SiGe alloy (pc-SiGe) in the vicinity of 400 cm ^-1 has slightly appeared. This state corresponds to the structure schematically shown in FIG. 4D. Formation of the a-Si band indicates that silicon fine particles are melted as the SiGe alloy is formed. On the other hand, in FIG. 11 (b) of the microscopic Raman spectrum of the portion II where firing is caused by heat transfer from the laser irradiated portion although it is a laser non-irradiated portion, polycrystalline germanium (pc-Ge) is present at 304 cm ^−1. ) Was remarkably observed. However, no pc-SiGe band around 400 cm ⁻¹ was observed. This is because the heating by heat transfer to the unirradiated part under the laser irradiation condition at a scanning speed of 4000 μm / s does not cause sufficient heating to form the SiGe alloy. This state corresponds to the structure schematically shown in FIG. 4B.

  In the microscopic Raman spectrum of the laser irradiation part of FIG. 11A, the fact that no pc-Ge band is observed indicates that germanium has diffused into the silicon bulk layer through the formation of the SiGe alloy. It is. When the germanium resin is mineralized, in the case of a composition containing 20 wt% germanium resin, the weight ratio of Si and Ge is about 8: 1, and the element ratio of Si and Ge is 20: 1. When the SiGe alloy is uniformly formed from the surface to the inside of the silicon fine particles, the intensity ratio of the Raman band to Si of the SiGe alloy becomes considerably small considering the element ratio of Si and Ge. This agrees with the result of the Raman spectrum of FIG. Also from the results of Examples 3 and 6, the germanium resin acts as a fusing agent for silicon fine particles, and is effective in forming a film composed of a continuous phase of silicon from silicon fine particles, and the amount to be added is reduced. This suggests that a silicon film having a small influence of germanium addition can be formed.

  On the other hand, germanium is unevenly distributed on the surface of the silicon fine particles that are not completely melted in the portion II in FIG. A high pc-Ge band was observed. This state corresponds to the structure schematically shown in FIG. 4B.

FIG. 12 is a microscopic Raman spectrum of the laser irradiation film pattern of the silicon fine particle germanium resin composition prepared in Example 4 under an Ar atmosphere. FIGS. 12A, 12B, and 12C are microscopic Raman spectra at portions I, II, and III in FIG. 9, respectively. In FIG. 12A, a sharp band of 520 cm ⁻¹ is attributed to polycrystalline silicon (pc-Si). Amorphous silicon in the vicinity of 470 cm ^-1 in addition to (a-Si), Raman bands attributed to the polycrystalline SiGe alloy (pc-SiGe) in the vicinity of 400 cm ^-1 has slightly appeared. This state corresponds to the structure schematically shown in FIG. 4D.

On the other hand, in FIG. 12 (b) of the microscopic Raman spectrum of the portion II where firing is caused by heat transfer from the laser irradiated portion although it is an unirradiated portion of the laser, it is 406 cm ⁻¹ to pc-SiGe and 304 cm ^{−. In 1} , a band attributed to pc-Ge was remarkably observed. The scanning speed of the laser beam in this case is 400 μm / s, which is one order of magnitude lower than 4000 μm / s in the case of Example 6, so that heating by heat transfer is likely to occur. In the region of II, the band of pc-SiGe is remarkably observed compared with the region of I. The heating temperature of the region of II is lower than that of the region of I, and the diffusion of germanium into the silicon bulk layer is This is because pc-SiGe is unevenly distributed on the surface of the Si layer. This state corresponds to the structure schematically shown in FIG. 4C.

  In FIG. 12C of the microscopic Raman spectrum of the region III further away from the laser irradiation region I, the pc-SiGe band disappears. This is because heat transfer is insufficient at the part III away from the laser irradiation part, and sufficient heating does not occur to form the SiGe alloy. This state corresponds to the structure schematically shown in FIG. 4B.

  13 (a), (b) and (c) show a pre-firing film, a film fired in an electric furnace at 250 ° C. under vacuum, and 900 under vacuum in the silicon fine particle germanium resin composition prepared in Example 1. The microscopic Raman spectra of the films fired in the electric furnace at 0 ° C. are shown. A band attributed to pc-Ge that does not appear in the pre-fired film appears in the 250 ° C. fired film. This state corresponds to the structure schematically shown in FIG. 4B.

The 900 ° C. fired film, in addition to the pc-Ge, the band of the pc-SiGe around 400 cm ^-1 in the vicinity of 300 cm ^-1, around 490 cm ^-1, bands shoulder has appeared to be attributable to a-Si. Considering that the melting point of silicon is 1410 ° C., the generation of such a-Si is a phenomenon that occurs when a SiGe alloy is formed. Although the melting point of germanium is 942 ° C., it is suggested that Si in the surface layer of silicon fine particles coated with germanium resin is melted with the formation of SiGe alloy by heating at a temperature near the melting point of germanium. That is, the germanium resin used as a dispersion medium in the present invention promotes the melting of Si with the formation of a SiGe alloy, and enables the melting and binding of silicon fine particles at a temperature lower than the melting point of Si. It is a substance that acts as a fusing agent.

  FIG. 14A is a confocal laser micrograph of the laser irradiation film pattern created in Example 3 under an Ar atmosphere. The current-voltage characteristics of the film pattern are shown in FIG. 14B. An InGa alloy was applied to the film pattern to form an ohmic contact, and current-voltage characteristics were measured. From the resistance value from the slope of the current-voltage characteristic and the shape of the measurement sample, the resistivity was calculated to be 867 Ωcm. Since the resistivity of the bulk n-Si single crystal used was 2 Ωcm, the resistivity was increased by forming fine particles by pulverization, forming a silicon fine particle germanium resin composition film, and forming a film pattern by laser irradiation. . This is because the measurement sample this time is a film having a thickness of 14 μm, and the effect of the film surface is significantly affected as compared with a bulk single crystal silicon substrate. The effect of the atmosphere in laser irradiation, for example, passivation of the semiconductor film surface by using Ar gas diluted hydrogen gas or the like is one of the techniques for improving electrical properties.

FIG. 15 shows current-voltage characteristics of the film pattern created in Example 3 under pulsed light irradiation. An InGa alloy was applied to the film pattern to form an ohmic contact, and current-voltage characteristics were measured. Light (62 mW / cm ² ) from a mercury xenon lamp was pulsed by opening and closing an electromagnetic shutter, and the IV characteristics under on-off irradiation at intervals of 5 seconds were measured. Photocurrent was observed with good response by irradiation with pulsed light. Thereby, the photoconductivity peculiar to a semiconductor material was able to be confirmed.

DESCRIPTION OF SYMBOLS 11 Optical microscope 12 Objective lens 13 Objective lens cover 14 Gas introduction tube 15 Board | substrate 16 Computer 17 xyz stage 18 Electromagnetic shutter 19 CCD camera 20 Shutter controller 21 Stage controller

Claims (6)

  A composition film formed from a dispersion obtained by mixing a germanium resin having an organic substituent in the side chain and silicon fine particles having an average particle diameter of 1 μm or more in an organic dispersion medium is obtained by heat treatment or laser irradiation. A silicon-germanium film characterized by this.   The main chain skeleton synthesized using germanium tetrachloride as a starting material is composed of a three-dimensional Ge—Ge bond, and the germanium resin having an organic substituent in the side chain covers the surface of the silicon particles and the germanium resin. A method for producing a silicon-germanium film, comprising mixing and pulverizing silicon particles, forming a composition obtained by mixing the mixed pulverized material in an organic dispersion medium, and then performing heat treatment or laser irradiation.   3. The method for producing a silicon-germanium film according to claim 2, wherein the germanium resin has a glass transition temperature of room temperature or lower.   4. The silicon-germanium film according to claim 2, wherein the composition obtained by mixing the germanium resin and the silicon fine particles in an organic dispersion medium is applied to a substrate in the air to form a film. Production method.   5. The organic substituent of the germanium resin on the surface of the silicon fine particles coated with the germanium resin is removed by heating or laser irradiation, and inorganic germanium and silicon are alloyed. The manufacturing method of the silicon- germanium film | membrane of description. 6. The method for producing a silicon-germanium film according to claim 5, wherein, in the laser irradiation step, a portion not affected by the heat of the laser is washed away with an organic solvent.