JP2009062253A - Method for forming silicon film - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for forming a silicon film which enables to form a dense and good silicon film. <P>SOLUTION: After preparing a solution containing a silane compound (S101), a coated film is formed on a substrate by using the solution containing the silane compound (S102). After heat treating the coated film (S103), the silicon film is formed by pressure treatment (S104). Thereby the silane compound in the coated film is decomposed, linkages between silicon atoms and linkages between a silicon atom and an atom other than silicon atom are cleft and linkages between silicon atoms are reconstructured. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a method for forming a silicon film by a coating method.

Conventionally, as a method for forming an amorphous silicon film or a polycrystalline silicon film, a thermal CVD (Chemical Vapor Deposition) method using a silane hydride gas, a plasma CVD method, a photo CVD method, a vapor deposition method or a sputtering method has been used. ing. In general, a plasma CVD method (for example, see Non-Patent Document 1) is widely used for forming an amorphous silicon film, and a thermal CVD method (for example, see Non-Patent Document 2) for forming a polycrystalline silicon film. .) Is widely used.
Spear W. E. , Solid State Com. 1975, Vol. 17, p. 1193 Kern W. , J .; Vac. Sci. Technol. 1977, 14 (5), p. 1082

When an amorphous silicon film is formed by plasma CVD, silane (SiH ₄ ) or disilane (Si ₂ H ₆ ) is decomposed by glow discharge as a hydrogenated silane gas, which is a raw material gas, and grown on the substrate. Thus, an amorphous silicon film is formed. In this case, the substrate is formed at about 400 ° C. or lower using crystalline silicon, glass, heat-resistant plastic or the like. With this plasma CVD method, a large area can be manufactured at a relatively low cost. Note that the polycrystalline silicon film is irradiated with a pulsed excimer laser at an interval of about 25 ns on the formed amorphous silicon film, so that the amorphous silicon film is heated and dissolved, and then re- Formed by crystallization.

In addition, a method for forming an amorphous silicon film by a CVD method using high-order hydrogenated silane has been proposed. Specifically, a method of thermally decomposing high-order hydrogenated silane gas under a pressure equal to or higher than atmospheric pressure (see, for example, Patent Document 1) and a method of thermally decomposing cyclic hydrogenated silane gas (for example, see Patent Document 2). And a method using branched hydrogenated silane (see, for example, Patent Document 3), a method in which higher-order hydrogenated silane gas higher than trisilane is thermally CVD at 480 ° C. or lower (for example, see Patent Document 4).
Japanese Patent Publication No. 04-062073 Japanese Patent Publication No. 05-000469 Japanese Patent Laid-Open No. 60-026665 Japanese Patent Publication No. 05-056852

  However, these CVD methods have problems such as a reduction in device yield. Specifically, since the raw material of the film is used in a gaseous state, it is difficult to obtain a film having a good step coverage on a substrate having an uneven surface, and the throughput is low due to the low film formation speed. is there. In addition, there are problems such as contamination of the apparatus due to generation of particles in the gas phase and the need for complicated and expensive apparatuses such as a high-frequency generator and a high vacuum apparatus in the plasma CVD method.

On the other hand, it has been studied to form a silicon film by a coating method that does not require an expensive apparatus. For example, after a coating film is formed on a substrate with a solution containing a liquid hydrogenated silane compound, the temperature is raised and a thermal history including a temperature raising process is performed to cause the hydrogenated silane compound to decompose and react in the coating film. A method of forming a silicon film has been reported (for example, see Patent Document 5). Also reported is a method of forming a silicon film by irradiating a solution containing cyclopentasilane as a hydrogenated silane compound with ultraviolet light, forming a coating film on the substrate using this solution, and heating the coating film. (For example, see Patent Document 6)
Japanese Patent No. 3517934 Japanese Patent No. 3424232

  In the techniques described in Patent Documents 5 and 6 described above, when a coating film is formed, the viscosity of a solution containing a hydrogenated silane compound is adjusted using a solvent to improve the film formability. However, when the solvent is volatilized from the coating film, the formed silicon film becomes dense, and it tends to be difficult to obtain sufficient electrical characteristics and mechanical characteristics.

  The present invention has been made in view of such problems, and an object thereof is to provide a silicon film forming method capable of forming a good silicon film.

  The method for forming a silicon film of the present invention includes a step of forming a coating film containing a silane compound on a substrate, and a first step of performing at least one of heat treatment and light irradiation on the substrate on which the coating film is formed. It includes a processing step and a second processing step of applying a pressure treatment to the substrate on which the coating film is formed.

  In the method for forming a silicon film according to the present invention, the step of applying a pressure treatment, which is the second processing step, includes a three-dimensional natework of Si—Si bonds, and a dense silicon film is formed. Is done.

  According to the method for forming a silicon film of the present invention, since the step of applying a pressure treatment, which is the second processing step, is included, a good silicon film can be formed. Further, for example, an expensive and complicated apparatus is not required as compared with a method that requires a vacuum process such as a CVD method, so that a silicon film can be formed easily and at low cost.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

[First Embodiment]
FIG. 1 shows a flow of a silicon film forming method according to the first embodiment of the present invention.

  First, a solution containing a silane compound is prepared (Step S101). The “silane compound” is a compound formed by bonding a silicon atom to a main chain and bonding silicon or an atom other than silicon to the silicon atom. The term “solution containing a silane compound” means a liquid containing a silane compound. If the silane compound exhibits a liquid, it is also a solution containing a silane compound, and is a polymer silane compound. A solution in which a silane compound is dissolved or dispersed in a liquid low-molecular silane compound, or a solution in which a silane compound is dissolved or dispersed in a solvent is also used as a solution containing the silane compound. For this reason, the solution containing a silane compound is adjusted by mixing any one or more of the silane compounds with a solvent, an additive, or the like as necessary.

  In this step S101, there is no particular limitation unless the atmosphere is mixed with a gas that easily reacts with a silane compound such as oxygen gas, but an inert gas such as argon, nitrogen or helium, or a reducing gas such as hydrogen gas is mixed. It is preferable to adjust in the atmosphere. Note that the same applies to the steps (steps S102 to S104) described below, which are preferably performed in an atmosphere in which an inert gas or a reducing gas is mixed.

  Examples of the silane compound include a monocyclic silane compound, a cyclic compound in which two monocyclic silane compounds are linked, a ladder-like cyclic compound in which two monocyclic silane compounds share two or more silicon atoms, or a single silane compound. Examples thereof include a cyclic silane compound such as a cyclic compound in which a cyclic silane compound is three-dimensionally linked, a linear silane compound, or a branched silane compound. These may be used singly or as a mixture of plural kinds. Among them, a compound represented by Chemical Formula 1 which is a monocyclic silane compound, a compound represented by Chemical Formula 2 which is a linear silane compound or a branched silane compound, or a cyclic compound in which two monocyclic silane compounds are linked. It is preferable to contain at least one of the compound shown in 3 and the compound shown in Chemical Formula 4 which is a cyclic compound in which monocyclic silane compounds are linked three-dimensionally. This is because a versatile and good silicon film is formed. R1 in Chemical Formula 1 may be the same as or different from each other, and the same applies to R2 in Chemical Formula 2, R3 in Chemical Formula 3, and R4 in Chemical Formula 4.

(Chemical formula 1)
Si _p R1 _2p
(R1 is a hydrogen group or a halogen group. P is an integer of 4 or more and 10 or less.)

(Chemical formula 2)
Si _q R2 _{2q + 2}
(R2 is a hydrogen group or a halogen group. Q is an integer of 3 or more and 10 or less.)

(Chemical formula 3)
Si _r R3 _2r-2
(R3 is a hydrogen group or a halogen group. R is an integer of 3 or more and 10 or less.)

(Chemical formula 4)
Si _s R4 _s
(R4 is a hydrogen group or a halogen group. S is an integer of 6 or more and 20 or less.)

  Examples of R1 include a hydrogen group and a halogen group such as a fluorine group, a chlorine group, a bromine group, or an iodine group. Among them, a hydrogen group is preferable. This is because a high effect can be obtained. The same applies to R2, R3 and R4. The reason why p in Chemical Formula 1 is in the above-described range is that the solution property is ensured and sufficient coatability is obtained. In detail, when it is smaller than the above range, it tends to be an unstable compound as a liquid, and when it is larger than the above range, it is compatible with other silane compounds or is soluble when using a solvent. This is because it becomes difficult to obtain sufficient. The same applies to q in Chemical Formula 2, r in Chemical Formula 3, and s in Chemical Formula 4.

Examples of the compound (Si _p H _2p ) in which R 1 is a hydrogen group include cyclotetrasilane (Si ₄ H ₈ ), cyclopentasilane (Si ₅ H ₁₀ ) represented by Chemical Formula ₅ , and cyclohexasilane (Si _6). H ₁₂ ) or cycloheptasilane (Si ₇ H ₁₄ ).

Examples of the compound (Si _q H _{2q + 2} ) in which R 2 is a hydrogen group include trisilane (Si ₃ H ₈ ), normal tetrasilane (Si ₄ H ₁₀ ), isotetrasilane (Si ₄ H ₁₀ ), normal penta silane (Si ₅ H _12), isopentanoyl silane (Si ₅ H _12), neopentasilane (Si ₅ H _12), normal hexa silane (Si ₆ H _14), Putashiran to the normal (Si ₇ H _16), normal octa Examples include silane (Si ₈ H ₁₈ ), normal nonasilane (Si ₉ H ₂₀ ), and isomers thereof.

Examples of the compound (Si _r H _2r-2 ) in which R 3 is a hydrogen group include 1,1′-biscyclobutasilane, 1,1′-biscyclopentasilane, 1,1′-biscyclohexasilane, 1,1′-biscycloheptasilane, 1,1′-cyclobutasilylcyclopentasilane, 1,1′-cyclobutasilylcyclohexasilane, 1,1′-cyclobutasilylcycloheptasilane, 1,1 ′ -Cyclopentasilylcyclohexasilane, 1,1'-cyclopentasilylcycloheptasilane, 1,1'-cyclohexasilylcycloheptasilane, spiro [2,2] pentasilane, spiro [3,3] heptatasilane, spiro [ 4,4] nonasilane, spiro [4,5] decasilane, spiro [4,6] undecasilane, spiro [5,5] undecasilane, spiro [5,6] dodecaci An example is orchid or spiro [6,6] tridecasilane.

Examples of the compound (Si _s H _s ) in which R 4 is a hydrogen group include a series of compounds represented by Chemical Formula 6.

These may be used alone or as a mixture of plural kinds. In addition to the above silane compound, monosilane and disilane may be mixed. In addition, a compound represented by Si _q H _{2q + 2} , which is a compound in which hydrogen of Si _p H _2p which is a cyclic compound is substituted with a silyl group, or a compound in which hydrogen of Si _s H _s is substituted with a silyl group. May be. Of these, cyclopentasilane is preferred. This is because a high effect can be obtained.

  A synthesized silane compound may be used as it is, or an isolated silane compound may be used. Here, as an example of a method for synthesizing a silane compound, a method for synthesizing cyclopentasilane will be described. When synthesizing cyclopentasilane, first, for example, phenyldichlorosilane dissolved in tetrahydrofuran is cyclized with metallic lithium to synthesize decaphenylcyclopentasilane. Next, decaphenylcyclopentasilane is treated with hydrogen chloride in the presence of aluminum chloride, then treated with lithium aluminum hydride, and purified by vacuum distillation to synthesize cyclopentasilane.

  The silane compound preferably contains a polymer of the silane compound described above. This is because the formation speed of the silicon film is improved and a good silicon film is formed. As this polymer, for example, a photopolymer polymerized by irradiating a silane compound with light in an inert gas atmosphere can be mentioned. Specifically, for example, a photopolymer is obtained by dissolving cyclopentasilane in a solvent and irradiating the solution with light in the ultraviolet region at room temperature to about 100 ° C. in an inert gas atmosphere such as argon, nitrogen or helium. Is synthesized. At this time, the wavelength of the irradiated light is preferably 200 nm or more and 450 nm or less. In particular, it is preferable to irradiate light of 200 nm or more and less than 320 and light of 320 nm or more and 450 nm or less. As a result, the Si—Si bond of the silane compound and part or all of the bond between the silicon atom and hydrogen or halogen are efficiently cleaved, and the Si—Si bond is constructed again. Examples of light sources used for light irradiation include low-pressure or high-pressure mercury lamps, deuterium lamps, discharge light of rare gases such as argon, krypton, and xenon. In addition, YAG (yttrium, aluminum, gallium) Examples include lasers, argon lasers, carbon dioxide lasers, and excimer lasers such as XeF, XeCl, XeBr, KrF, KrCl, ArF, and ArCl.

  Any solvent can be used as long as it dissolves, disperses or compatibilizes with the silane compound and does not react with the silane compound. Examples of the solvent include hydrocarbon solvents such as n-heptane, n-octane, decane, toluene, xylene, cymene, durene, indene, dipentene, tetrahydronaphthalene, decahydronaphthalene or cyclohexylbenzene, ethylene glycol dimethyl ether, Ether solvents such as ethylene glycol diethyl ether, ethylene glycol methyl ethyl ether, diethylene glycol dimethyl ether, diethylene glycol methyl ethyl ether, 1,2-dimethoxyethane, bis (2-methoxyethyl) ether or p-dioxane, propylene carbonate, γ- Such as butyl lactone, n-methyl-2-pyrrolidone, dimethylformaldehyde, dimethyl sulfoxide or cyclohexanone It includes protic polar solvent. These may be used singly or as a mixture of plural kinds.

  In addition, when preparing the solution containing a silane compound using a solvent, content of the silane compound in a solution is arbitrary by the kind of silane compound, the thickness of the silicon film to form, etc., for example, 0 It is preferably 1% by weight or more and 60% by weight or less. This is because sufficient coatability is obtained and a good silicon film is formed. Specifically, when it is less than 0.1% by weight, there are many voids when the solvent is volatilized after application, and it becomes difficult to form a good silicon film, and when it exceeds 60% by weight, the viscosity of the solution is high. It is because it becomes difficult to obtain sufficient applicability. Especially, it is preferable that it is 1 to 40 weight%, and it is more preferable that it is 5 to 30 weight%. This is because a higher effect can be obtained.

  Moreover, as an additive, any 1 type (s) or 2 or more types of radical generators may be included. Examples of the radical generator include biimidazole compounds, benzoin compounds, triazine compounds, acetophenone compounds, benzophenone compounds, α-diketone compounds, polynuclear quinone compounds, xanthone compounds, and azo compounds. . When the radical generator is included, the content thereof is preferably 0.01% by weight to 30% by weight and more preferably 0.5% by weight to 20% by weight with respect to the silane compound. It is more preferable. In addition to the radical generator, the additive may include a p-type impurity used when forming the p-type semiconductor and an n-type impurity used when forming the n-type semiconductor.

  Next, a coating film is formed by applying a solution containing a silane compound on the substrate (step S102). The substrate is arbitrary, and examples thereof include a glass substrate, a quartz substrate, a plastic substrate, a silicon film such as a silicon nitride film, a silicon oxide film, an amorphous silicon film, or a polycrystalline silicon film. Examples of the method for forming the coating film include spin coating, dip coating, spraying, and dipping. The temperature at which the coating film is formed may be about 100 ° C., for example. Of these, spin coating is preferred. In this case, the rotation speed of the spinner is arbitrary depending on the composition and viscosity of the solution containing the silane compound, or the thickness of the coating film, and is preferably 100 rpm or more and 8000 rpm or less, and 500 rpm or more and 6000 rpm or less. Is more preferable. This is because a good coating film is formed.

  Subsequently, as a first processing step, the formed coating film is heat-treated (step S103). By applying heat treatment to the coating film, the silane compound contained in the coating film is thermally decomposed, the bonds between silicon atoms and silicon atoms are reconstructed, and a three-dimensional network in the silicon film is formed. Specifically, this thermal decomposition causes part or all of the bond between the silicon atom and silicon atom, and part or all of the bond between the silicon atom and non-silicon atom to reconstruct the Si-Si bond. Is done. Also in this step S103, it is preferable to perform the treatment in an atmosphere mixed with an inert gas or a reducing gas.

  The temperature of the heat treatment can be arbitrarily set depending on whether the silicon film is formed in an amorphous state (amorphous state) or in a polycrystalline state. Usually, when the ultimate temperature is about 400 ° C. or lower, an amorphous silicon film is formed, and a polycrystalline silicon film having a higher temperature is formed. The heat treatment temperature is preferably 100 ° C. or higher and 500 ° C. or lower. This is because a good silicon film is formed. Specifically, when the temperature is lower than 100 ° C., the silane compound contained in the coating film may not be sufficiently decomposed, and when the temperature exceeds 500 ° C., the decomposed product of the silane compound is likely to volatilize. Especially, it is preferable that it is 200 to 400 degreeC.

  Subsequently, the silicon film formed as the second treatment process is subjected to pressure treatment (step S104). The pressure treatment is performed by reducing the vacancies formed by volatilization of the decomposition product of the silane compound during the heat treatment, and the three-dimensional network of Si-Si bonds is made dense and good. This is for forming a silicon film. Also in this step S104, it is preferable to perform the treatment in an atmosphere mixed with an inert gas or a reducing gas. It is preferable to pressurize the temperature in this case at about 200 ° C.

  The pressure treatment can be arbitrarily set as long as it is higher than 1 atm (0.1001325 MPa), and preferably 2 atm (0.20 MPa) or more and 200 atm (20.27 MPa) or less. This is because a three-dimensional network is efficiently formed and a dense and good silicon film is formed. Specifically, if it is less than 2 atmospheres, it is difficult to promote a three-dimensional network, and if it is more than 200 atmospheres, it is difficult to form a pressurizing function. Especially, 5 atmospheres (0.51 MPa) or more and 100 atmospheres (10.13 MPa) or less are preferable. This is because a denser and better silicon film is formed.

  Thereby, a silicon film is formed. This silicon film can be used in devices such as LSI (Large Scale Integration), TFT (Thin Film Transistor), or photoelectric conversion elements such as solar cells.

  In the method for forming a silicon film of the present embodiment, after forming a coating film containing a silane compound, the silane compound is thermally decomposed by heat treatment, and a part or all of the bonds between silicon atoms and silicon atoms, and Part or all of the bond between a silicon atom and an atom other than a silicon atom is cleaved. Thereafter, the Si—Si bonds are reconstructed, and a three-dimensional network of Si—Si bonds in the silicon film is formed. Next, by applying pressure treatment, the fine vacancies formed by volatilization of the decomposition product of the silane compound during heat treatment are reduced by filling the pores, thereby promoting the three-dimensional networking of Si-Si bonds. .

  According to this method for forming a silicon film, since it includes a pressure treatment step, a three-dimensional network of Si-Si bonds is formed more densely than when no pressure treatment is performed, and a good silicon film is formed. can do. Moreover, for example, an expensive and complicated apparatus is not required as compared with a method that requires a vacuum process such as a CVD method, so that a silicon film can be formed easily and at low cost.

  In particular, if the pressure of the pressure treatment is set to 0.02 MPa or more and 2 MPa or less, a better silicon film can be formed. In that case, a better silicon film can be formed in an atmosphere in which an inert gas containing at least one of argon, nitrogen, and helium, or a reducing gas containing hydrogen gas is mixed.

  Further, if at least one of the compounds shown in Chemical Formula 1, Chemical Formula 2, Chemical Formula 3 and Chemical Formula 4 is used as the silane compound, a high effect can be obtained.

  Further, in the heat treatment step, if the temperature is set to 100 ° C. or higher and 500 ° C. or lower, or 200 ° C. or higher and 400 ° C. or lower, high effects can be obtained.

  When a solvent is contained in the coating film, that is, when a solution prepared by mixing the solvent with the silane compound is used when forming the coating film, the solvent is slightly evaporated in the heat treatment step. Since many vacant holes are formed, a particularly high effect can be obtained by the pressure treatment.

  Although other embodiments of the present invention will be described below, common constituent elements will be denoted by the same reference numerals and description thereof will be omitted.

[Second Embodiment]
FIG. 2 shows a flow of a silicon film forming method according to the second embodiment. In the second embodiment, the first embodiment is different from the first embodiment except that the first heat treatment (step S103) and the second pressure process (step S104) are performed simultaneously. It is the same.

  After forming the coating film (step S102), the coating film is subjected to pressure treatment while being heat-treated (step S105). However, when the solvent is included in the coating film, that is, when a solution prepared by mixing the solvent with the silane compound is used when forming the coating film, there is a step of volatilizing the solvent before step S105. is necessary. This is because the solvent may remain in the coating film by performing the heat treatment and the pressure treatment at the same time. In order to volatilize the solvent, for example, the solvent may be heated at about 100 ° C. to 200 ° C. or reduced in pressure. Of course, it is preferable to volatilize in an inert gas or reducing gas atmosphere.

  The heat treatment condition and the pressure treatment condition are the same as those in steps S103 and S104 in the first embodiment. Also in this step S105, it is preferable to perform the treatment in an atmosphere mixed with an inert gas or a reducing gas.

  In the method for forming a silicon film in the second embodiment, the heat treatment and the pressure treatment are performed at the same time, so that volatilization of the decomposition product of the silane compound by the heat treatment is suppressed, and minute vacancies are reduced. In addition, the minute holes formed are reduced by filling, and a three-dimensional network of Si—Si bonds is efficiently formed.

  According to this silicon film formation method, the heat treatment and the pressure treatment are performed at the same time, so that a three-dimensional network of Si—Si bonds is formed more densely and better than the case where the pressure treatment is performed after the heat treatment. A simple silicon film can be formed. In addition, the number of steps can be reduced.

  Other functions and effects are the same as those in the first embodiment.

  In this embodiment, the pressure treatment is performed while performing the heat treatment in step S105. However, if the heat treatment and the pressure treatment are performed at the same time, the timing for starting and ending each treatment is arbitrarily set. Is possible. That is, the pressure treatment may be started after the heat treatment is started, or the heat treatment may be started after the pressure treatment is started. Thereby, the above-described operational effects can be obtained.

[Third Embodiment]
FIG. 3 shows a flow of a silicon film forming method according to the third embodiment. The third embodiment is the same as the first embodiment except that light irradiation (step S203) is performed instead of the heat treatment (step S103) as the first processing step.

  After forming the coating film (step S102), the coating film is irradiated with light (step S203). However, when the coating film contains a solvent, that is, when a solution prepared by mixing the solvent with the silane compound is used when forming the coating film, a step of volatilizing the solvent is required. This is because the solvent may remain in the coating film. Note that the step of volatilizing the solvent may be performed simultaneously with step S203 or may be performed before step S203. In order to volatilize the solvent, for example, the solvent may be heated at about 100 ° C. to 200 ° C. or reduced in pressure. Of course, it is preferable to volatilize in an inert gas or reducing gas atmosphere.

  Conditions such as the wavelength of light to be irradiated are the same as in the case of synthesizing a photopolymer of a silane compound in the first embodiment. Of course, it is preferable to irradiate with light in an inert gas or reducing gas atmosphere, and the temperature in this case is about room temperature to about 100 ° C.

  In the method for forming a silicon film according to the third embodiment, after forming a coating film containing a silane compound, the silane compound is photodecomposed by irradiating light to bond silicon atoms in the silane compound to silicon atoms. And all or a part or all of the bonds between silicon atoms and atoms other than silicon atoms are cleaved. Thereafter, the Si—Si bonds are reconstructed, and a three-dimensional network of Si—Si bonds in the silicon film is formed. Next, by pressurizing, the fine vacancies formed by volatilization of the photodecomposition product of the silane compound are reduced, and the three-dimensional network of dense Si-Si bonds is densely formed. To.

  According to this method for forming a silicon film, since it includes a pressure treatment step, a three-dimensional network of Si-Si bonds is formed more densely than when no pressure treatment is performed, and a good silicon film is formed. can do. Moreover, for example, an expensive and complicated apparatus is not required as compared with a method that requires a vacuum process such as a CVD method, so that a silicon film can be formed easily and at low cost.

  In particular, a better silicon film can be formed by irradiating light having a wavelength of 200 nm to 450 nm or irradiating light having a wavelength of 200 nm to less than 320 nm and light having a wavelength of 320 nm to 450 nm. In that case, a better silicon film can be formed in an atmosphere in which an inert gas containing at least one of argon, nitrogen, and helium, or a reducing gas containing hydrogen gas is mixed.

  Further, if at least one of the compounds shown in Chemical Formula 1, Chemical Formula 2, Chemical Formula 3 and Chemical Formula 4 is used as the silane compound, a high effect can be obtained.

  Note that although a heat treatment step is not included in this embodiment mode, heat treatment may be performed at the time of light irradiation or after light irradiation. Thereby, a better silicon film can be obtained than when heat treatment is not performed.

  In the present embodiment, the light irradiation is performed after forming the coating film. However, the light irradiation may be performed while forming the coating film.

[Fourth Embodiment]
FIG. 4 shows a flow of a silicon film forming method according to the fourth embodiment. In the fourth embodiment, the third embodiment is performed except that the light irradiation (step S203) as the first processing step and the pressurizing process (step S104) as the second processing step are performed simultaneously. It is the same.

  After forming the coating film (step S102), the coating film is pressurized while being irradiated with light (step S204). However, when the solvent is included in the coating film, that is, when a solution prepared by mixing the solvent with the silane compound is used when forming the coating film, the step of volatilizing the solvent is performed before step S204. is necessary. This is because the solvent remains in the coating film. The method for volatilizing the solvent is the same as in the second and third embodiments.

  The conditions for light irradiation and the conditions for the pressure treatment are the same as those in the third embodiment.

  In the method for forming a silicon film according to the fourth embodiment, the light irradiation step and the pressure treatment step are performed at the same time, thereby suppressing the volatilization of the decomposition product of the silane compound and reducing the fine pores. In addition, the formed minute vacancies are reduced by filling, and a three-dimensional network of Si—Si bonds is efficiently formed densely.

  According to this silicon film formation method, the light irradiation step and the pressure treatment step are performed simultaneously, so that a three-dimensional network of Si—Si bonds is more dense than the case where pressure treatment is performed after light irradiation. Thus, a good silicon film can be formed. In addition, the number of steps can be reduced.

  Other functions and effects are the same as those of the third embodiment.

  Note that although a heat treatment step is not included in this embodiment mode, heat treatment may be performed at the time of light irradiation or after the light irradiation step. As a result, a better silicon film can be formed than when heat treatment is not performed.

  Examples of the present invention will be described in detail.

Example 1
A silicon film was formed according to the flow of FIG.

First, a solution containing a silane compound was prepared. At this time, first, 2 ml of cyclopentasilane was filled in a quartz cell with a screw cap. Subsequently, a spot UV irradiator (LC-5 manufactured by Hamamatsu Photonics (with 03-type filter)) was brought into close contact with a region of the outer wall surface of the quartz cell and irradiated with light at an output of 3.6 W / cm ² . . The irradiation light from this spot UV irradiator has an irradiation wavelength range of 200 nm to 450 nm, has peaks at 290 nm and 305 nm in the wavelength range of 200 nm to less than 320 nm, and has a maximum peak at 365 nm in the wavelength range of 320 nm to 450 nm. And had a peak at 325 nm. When this light was irradiated on the quartz cell for 3 minutes, the viscosity of the solution increased. This solution was dissolved in a 10 ml toluene solution so as to be 30% by weight to obtain a coating solution.

  Next, a coating film was formed. At this time, the prepared coating solution was spin-coated on a glass substrate at 2000 rpm in an argon atmosphere to form a colorless and transparent polysilane film as a coating film. Subsequently, after the solvent was volatilized at 200 ° C., the polysilane film was baked at 350 ° C. under 2 atmospheres (0.20 MPa) in an argon atmosphere, whereby a silicon film having a metallic luster was obtained.

(Examples 2 to 8)
The pressure of the pressure treatment is 3 atm (0.30 MPa: Example 2), 5 atm (0.51 MPa: Example 3), 20 atm (2.03 MPa: Example 4), 30 atm (3.04 MPa: practice) Example 5), 50 atm (5.07 MPa: Example 6), 100 atm (10.13 MPa: Example 7) or 200 atm (20.27 MPa: Example 8) I went through the procedure.

Example 9
A procedure similar to that of Example 1 was performed except that the heat treatment was followed by the pressure treatment. At this time, the polysilane film was baked at 350 ° C. in an argon atmosphere and then subjected to pressure treatment at 2 atm (0.20 MPa) and 200 ° C. in an argon atmosphere, whereby a silicon film having a metallic luster was obtained.

(Examples 10 to 12)
Example 9 except that the pressure of the pressure treatment was 20 atm (2.03 MPa: Example 10), 100 atm (10.13 MPa: Example 11) or 200 atm (20.27 MPa: Example 12). The same procedure was followed.

(Comparative Example 1)
The same procedure as in Example 1 was performed except that no pressure treatment was performed.

  For the silicon films of Examples 1 to 12 and Comparative Example 1, the relative values of the film thickness, film quality (kind) and the peak intensity of the IR spectrum due to the Si—H bond were examined. The results shown in Table 1 were obtained. was gotten.

  The thickness of the silicon film was measured by observing the cross section with an SEM (scanning electron microscope). The film quality (kind) was evaluated by Raman measurement of the silicon film to determine whether it was amorphous or polycrystalline.

  For the relative value of the peak intensity of the IR spectrum due to the Si—H bond, the silicon film was measured by the IR spectrum, and the peak intensity due to the Si—H bond was measured. At this time, the peak intensity of Comparative Example 1 was set to 1, and the peak intensity ratio of Si—H bonds (Si—H peak intensity ratio) was determined as a relative value.

  As shown in Table 1, in Examples 1 to 12 and Comparative Example 1, an amorphous silicon film was formed. The thickness of the silicon film becomes thinner in Comparative Examples 1 to 12 in which the pressure during the pressure treatment is 0.20 MPa or more and 20.27 MPa or less compared to Comparative Example 1 where the pressure treatment is not performed. Therefore, it showed a tendency to become thinner. Moreover, in Examples 1-12, the peak intensity resulting from a Si-H bond became higher than the comparative example 1, and the Si-H peak intensity ratio which is the relative value became larger than 1. When an amorphous silicon film is formed using a hydrogenated silane compound such as cyclopentasilane, a Si-H bond is formed by forming a three-dimensional network of Si-Si bonds. The result shows that by applying pressure treatment, the micropores formed by the volatilization of cyclopentasilane decomposition products and the volatilization of toluene used as a solvent are reduced, and a three-dimensional network of Si-Si bonds is formed. Indicates that it has been promoted and refined. In this case, in Examples 1 to 12, if the pressure during pressurization is 0.20 MPa or more, the Si—H peak intensity ratio is greater than 1, and if it is 0.51 MPa or more, the Si—H peak intensity ratio is It became 2 or more.

  From this, it was confirmed that in the method for forming a silicon film, a dense and good silicon film is formed by including a pressure treatment step. In that case, a dense and good silicon film is formed if the pressure during the pressure treatment is 0.20 MPa or more and 20.27 MPa or less, and if the pressure is 0.51 MPa or more and 10.13 MPa or less, the denser and better silicon film is formed. It was confirmed that a simple silicon film was formed.

  In Examples 1, 4, 7, and 8 that were subjected to pressure treatment while heat treatment, each Si—H peak intensity ratio was higher than those in Examples 9 to 12 that were subjected to pressure treatment after heat treatment. This result indicates that the three-dimensional networking of Si—Si bonds is further promoted and becomes dense by performing the heat treatment and the pressure treatment at the same time.

  From this, it was confirmed that in the above-described silicon film formation method, a denser and better silicon film is formed by simultaneously performing the heat treatment step and the pressure treatment step.

  Although not shown in this embodiment, even when the silicon film is formed by irradiating the coating film with light, the pressure treatment is performed in the same manner as in the case where the silicon film is formed by heat treatment. It was confirmed that a good silicon film was formed.

  The silicon film forming method of the present invention has been described above with reference to the embodiments and examples. However, the present invention is not limited to the embodiments described in the above embodiments and examples, and the silicon film forming method is described above. The configuration of can be freely changed. For example, the usage application of the method for forming a silicon film of the present invention is not necessarily limited to a device such as a thin film transistor, LSI, or photoelectric conversion element, and may be another device or may be used for other applications. Examples of other applications include a photoreceptor.

It is a flowchart showing the formation method of the silicon film which concerns on the 1st Embodiment of this invention. It is a flowchart showing the formation method of the silicon film which concerns on the 2nd Embodiment of this invention. It is a flowchart showing the formation method of the silicon film which concerns on the 3rd Embodiment of this invention. It is a flowchart showing the formation method of the silicon film which concerns on the 4th Embodiment of this invention.

Claims (11)

Forming a coating film containing a silane compound on a substrate;
A first treatment step of performing at least one of heat treatment and light irradiation on the substrate on which the coating film is formed;
And a second treatment step of applying a pressure treatment to the substrate on which the coating film is formed.   2. The method of forming a silicon film according to claim 1, wherein, in the second treatment step, the pressure is set to 0.20 MPa (2 atm) or more and 20.27 MPa (200 atm) or less.   2. The method of forming a silicon film according to claim 1, wherein the first processing step and the second processing step are performed simultaneously.   2. The method of forming a silicon film according to claim 1, wherein the second processing step is performed after the first processing step. The second treatment step,
Performing in an atmosphere mixed with an inert gas containing at least one of the group consisting of argon (Ar), nitrogen (N ₂ ) and helium (He), or a reducing gas containing hydrogen (H ₂ ). 2. The method for forming a silicon film according to claim 1, wherein: The second treatment step,
Performing in an atmosphere mixed with an inert gas containing at least one of the group consisting of argon (Ar), nitrogen (N ₂ ) and helium (He), or a reducing gas containing hydrogen (H ₂ ). 3. The method for forming a silicon film according to claim 2, wherein: 2. The method of forming a silicon film according to claim 1, wherein the silane compound contains at least one of compounds represented by chemical formula 1, chemical formula 2, chemical formula 3 and chemical formula 4.
(Chemical formula 1)
Si _p R1 _2p
(R1 is a hydrogen group or a halogen group. P is an integer of 4 or more and 10 or less.)
(Chemical formula 2)
Si _q R2 _{2q + 2}
(R2 is a hydrogen group or a halogen group. Q is an integer of 3 or more and 10 or less.)
(Chemical formula 3)
Si _r R3 _2r-2
(R3 is a hydrogen group or a halogen group. R is an integer of 3 or more and 10 or less.)
(Chemical formula 4)
Si _s R4 _s
(R4 is a hydrogen group or a halogen group. S is an integer of 6 or more and 20 or less.)   The method for forming a silicon film according to claim 1, wherein the heat treatment is performed at 100 ° C. or more and 500 ° C. or less.   The method for forming a silicon film according to claim 1, wherein the heat treatment is performed at 200 ° C. or more and 400 ° C. or less.   2. The method of forming a silicon film according to claim 1, wherein the light irradiation is performed with light having a wavelength of 200 nm to 450 nm.   2. The method of forming a silicon film according to claim 1, wherein the light irradiation is performed with light having a wavelength of 200 nm to less than 320 nm and light having a wavelength of 320 nm to 450 nm.

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