JPH06191821A - Higher order silane containing solution for forming silicon film - Google Patents

Abstract

PURPOSE:To obtain a solution capable of safely and efficiently obtaining a uniform silicon film with a film coating method by using a specific solvent and dissolving it so as to be a specific conc. in producing a solution of forming silicon film by dissolving a higher order silane in an organic solvent. CONSTITUTION:The organic solvent selected from saturated hydrocarbons expressed by CaHb (3<=a<=16, 8<=b<=34), unsaturated hydrocarbons, aromatics (e.g. toluene), ethers expressed by CdHeOf(2<=d<=16, 6<=e<=34, 1<=f<=3), e.g. diethyletter or a mixed solvent of them is prepared. The higher order silane (e.g. trisilane) expressed by the formula ((n) >=2) is dissolved in the solvent so that the total higher order silane conc. in the solvent (total higher order silane weight)/(total higher order silane weight+solvent weight)X100) is 1-50wt.%. Thus, the higher order silane containing solution suitable for forming silicon film by the film coating method is obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an LSI, a thin film transistor, a photoelectric conversion device, and a high-order silane-containing solution used for forming a silicon film for photoconductor applications.

[0002]

2. Description of the Related Art Conventionally, a thermal CVD (Chemical Vapor Deposition) method, a plasma CVD method, an optical CVD method or the like has been used as a method for forming a polysilicon film or an amorphous silicon (hereinafter referred to as "a-Si") film. In general, a polysilicon film has a thermal CVD method (Kern, W. et al .: J. Vac.
Sci. Technol., 14 (5) (1977) p. 1082), a-
Plasma CVD method (Spear, WE et al .: Solid
State Com., Volume 17 (1975), page 1193) is widely used and commercialized.

However, when these vapor phase deposition methods are used, expensive high vacuum equipment is required. It is difficult to analyze the gas flow, the size of the device is larger than the size of the substrate, and the shape is restricted. Further, it is difficult to increase the area. Since the gas phase reaction is used, powder is generated in the gas phase, which causes problems such as device contamination and cleaning, and device yield. In addition, the film formation rate is slow and the throughput is poor. The plasma CVD method requires a complicated and expensive device such as a high frequency generator. Moreover, although gas is used as a raw material, most of them are explosive or toxic, and are dangerous in handling. On the other hand, there is a coating film method (SOG method) as a method which does not have the above defects in the vapor phase method. Although a coating film method is used for an interlayer insulating film, a flattening film and the like in LSI, there is no suitable solution for coating for a silicon film.

[0004]

A liquid raw material that can be used for forming a silicon film by a coating film method is required to contain no carbon or oxygen in its molecule. Therefore, the general formula Si _n H _{2n + is used.} Higher order silane represented by ₂ (where n is an integer of n ≧ 2) is suitable. However, in the state of only high-order silane, it is difficult to uniformly coat the high-order silane as a thin film on the substrate, and when exposed to the atmosphere, the high-order silane reacts with the atmospheric pressure and easily reacts with the atmosphere. Risk of burning. The present invention has been made in view of the above points, and an object thereof is to provide a solution that can be used for forming a silicon film by a coating film method without using a deposition method from a vapor phase.

[0005]

DISCLOSURE OF THE INVENTION The inventors of the present invention have made diligent efforts to achieve the above object, and as a result, the general formula Si _n H
_In a high-order silane-containing solution obtained by dissolving a high-order silane represented by _{2n + 2} (where n is an integer of n ≧ 2) in an organic solvent at a constant ratio, C _a H _b (provided that a is 3 ≦
a ≦ 16, b is an integer of 8 ≦ b ≦ 34), saturated hydrocarbons, unsaturated hydrocarbons, aromatics, or C _d
H _e O _f (where, d is 2 ≦ d ≦ 16, e is 6 ≦ e ≦ 34,
f is an integer of 1 ≦ f ≦ 3), or a high-order silane-containing solution using an ether or a mixed solvent thereof is used for forming a silicon film by a coating film method to obtain a high-quality silicon film. We have found that can be obtained safely and efficiently on a large area.

The high-order silane-containing solution of the present invention will be described below. The high-order silane used in the present invention as a liquid raw material which is dissolved in an organic solvent and applied on a substrate has a general formula Si _n H
_{2n + 2} (where n is an integer of n ≧ 2), and is represented by disilane (Si ₂ H ₆ ), trisilane (Si ₃ H ₈ ), tetrasilane (Si ₄ H ₁₀ ), pentasilane (Si ₅ H ₁₂ ), Alternatively, it is hexasilane (Si ₆ H ₁₄ ) or more. These higher order silanes may be used alone or as a mixture of two or more kinds.

The organic solvent used in the present invention may be any solvent in which the higher order silane is soluble, but it is desirable that the organic solvent has no reactivity with the higher order silane. Further, it is desirable to use an organic solvent having a boiling point of 300 ° C. or lower in order to prevent the solvent from remaining in the formed film. As such an organic solvent,
C _a H _b (where, a is 3 ≦ a ≦ 16, b is 8 integer of ≦ b ≦ 34) saturated hydrocarbons represented by, unsaturated hydrocarbons, aromatics, or C _d H _e O _f (where d is 2 ≦ d ≦ 16,
An ether represented by e is 6 ≦ e ≦ 34, and f is an integer of 1 ≦ f ≦ 3, or a mixed solvent thereof is used.
In terms of handling, it is preferably liquid at room temperature.

For example, C _a H _b (where a is 3 ≦ a
≦ 16, b is an integer of 8 ≦ b ≦ 34) and examples of saturated hydrocarbons, unsaturated hydrocarbons, and aromatics include propane, butane, pentane, 2-methylbutane, hexane,
2-methylpentane, 2,2-dimethylbutane, 2,3
-Dimethylbutane, heptane, 2-methylhexane, 3
-Methylhexane, dimethylpentane, octane, 2,
2,3-trimethylpentane, isooctane, nonane,
2,2,5-trimethylhexane, decane, dodecane,
Pentene, hexene, heptene, octene, nonene, decene, benzene, toluene, xylene, ethylbenzene, cumene, mesitylene, butylbenzene, diethylbenzene, styrene, cyclopentane, methylcyclopentane, cyclohexane, methylcyclohexane and the like.

[0009] C _d H _e O _f (where, d is 2 ≦ d ≦ 16, e 6
The ethers represented by ≦ e ≦ 34 and f is an integer of 1 ≦ f ≦ 3) include dimethyl ether, methyl ethyl ether, diethyl ether, dipropyl ether, diisopropyl ether, dibutyl ether, ethyl vinyl ether, butyl vinyl ether, and anisole. , Benzyl ethyl ether, diphenyl ether, dioxane, trioxane, furan, tetrahydrofuran, tetrahydropyran, 1,2-dimethoxyethane, 1,2-diethoxyethane, 1,2-dibutoxyethane, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, diethylene glycol di Butyl ether, glycerin ether, crown ether, methylal, acetal and the like. These organic solvents may be used alone or in combination of two or more.

The total high-order silane concentration (total high-order silane weight / (total high-order silane weight + solvent weight) × 100) in the solution of the high-order silane dissolved in the organic solvent in the present invention is preferably the total high-order silane concentration. It is 0.1 to 50% by weight.
When the high-order silane concentration is 50% by weight or more, the risk that the high-order silane corresponding to the vapor pressure reacts with the atmosphere and burns in the atmosphere is significantly increased. Total higher silane concentration is 0.1% by weight
In the following, it is difficult to obtain a film having a sufficient film thickness.

When forming a silicon film using the high-order silane-containing solution of the present invention, first, the high-order silane-containing solution is applied onto a substrate. In that case, spin coating method,
Alternatively, there is a method of pulling up after immersion, but in general, a spin coating method is often used. The spinner rotation speed in the spin coating method is generally 100 to 100.
00 RPM, preferably 300-6000 RPM is used. After coating, if necessary, the organic solvent is previously removed by evaporation from the high-order silane-containing solution, and then a predetermined silicon film is obtained by a method such as photopolymerization by ultraviolet light irradiation or thermal polymerization by heating. The film thickness of the silicon film obtained by using the high-order silane-containing solution of the present invention is 5 nm to
The thickness can be freely selected up to about 5 μm, but a film thickness of about 10 nm to 2 μm is preferably used.

The energy for decomposing the high-order silane according to claim 2 is irradiation with light having a wavelength of 400 nm or less, or 25
It means heating at 0 ° C or higher. When performing photopolymerization by ultraviolet light irradiation, as a light source of light to be generally irradiated,
A light source having a wavelength of 400 nm or less is used. This includes, for example, low pressure mercury lamp light, H ₂ , deuterium, Ar,
Discharge light of a rare gas such as Kr or Xe or excimer laser light is used. When the thermal polymerization is carried out by heating, it is generally carried out by heating at 250 to 700 ° C. for 10 to 120 minutes. In the above method, generally 450 to 5
An a-Si film is obtained at a temperature of 00 ° C. or lower, and a polysilicon film is obtained at a temperature of higher than that.

[0013]

Function General formula Si _n H _{2n + 2} (where n is an integer of n ≧ 2)
A high-quality silicon film can be formed by applying a solution in which a high-order silane represented by the following is dissolved in an organic solvent at a constant ratio to the substrate and then decomposing it to form a silicon film on the substrate. In the method of the present invention, since the high-order silane is used by being dissolved in an organic solvent, the high-order silane can be uniformly applied as a thin film by a coating film method, which allows the silicon to be uniformly applied at a selected film thickness on the substrate. A film can be formed.

In general, the higher order silane is a liquid or a liquefied gas that is spontaneously ignitable in the atmosphere, but since the higher order silane is used by dissolving it in an organic solvent in the method of the present invention, the spontaneous ignitability in the atmosphere is Significant reduction and easy handling. Since a liquid raw material is used in the method of the present invention, general CVD
Unlike the method, the device is easy and the generation of powder can be prevented. Further, a high-quality silicon film can be efficiently and safely formed on a large-area substrate, which was difficult by the conventional CVD method.

[0015]

The present invention will be described in detail with reference to the following examples, but the present invention is not limited thereto. The high-order silane-containing solution of the present invention was prepared as follows. First, a commercially available special grade reagent as an organic solvent was deaerated and dehydrated, and then purified by distillation and used. As the high-order silane, a mixed liquid having a constant composition or a liquid purified to almost a single high-order silane by distillation is used, and mixed with the organic solvent in an inert gas to a predetermined concentration while stirring. During the mixing, the pressure inside the system was kept slightly increased in order to prevent air from being mixed into the system. The order of mixing can be high-order silane dropped into the organic solvent or vice versa, but in order to prevent the high-order silane from adhering to the container, the high-order silane dropping port is installed near the surface of the organic solvent. did.

An example of an apparatus for forming a silicon film using the high-order silane-containing solution of the present invention is shown in FIGS. FIG. 1 shows an example in the case of performing photopolymerization by ultraviolet irradiation, and FIG. 2 shows an example in the case of performing thermal polymerization by heating. In the device of FIG. 1, a deuterium lamp 106 was used as a light source. Light is irradiated from the deuterium lamp 106 into the film forming chamber 101 through a light irradiation window 107 made of MgF ₂ . In the film forming chamber 101, a 100φ circular substrate stand 103 that can be heated by a heater or the like is provided, and the substrate 102 is held thereon. Deuterium lamp 106 has 1
The one with 50W and 25φ was installed. Light spectrum is 1
It is distributed from 15 nm to 400 nm and has a maximum peak at 160.8 nm. Substrate 1 coated with a high-order silane-containing solution
02 is held on the substrate table 103 in the film forming chamber 101,
An inert gas is introduced into the film forming chamber 101 by the inert gas flow meter 104, and the organic solvent is evaporated from the solution on the substrate 102 as needed. Evaporated organic solvent is exhaust system 10
Discharge through 5. High-order silane is decomposed by light irradiation in the film forming chamber 101, and a silicon film is deposited on the substrate 102.

In the apparatus shown in FIG. 2, a 100 φ circular substrate base 203 which can be heated by a heater or the like is provided in the film forming chamber 201, and the substrate 202 is held thereon. After the substrate 202 coated with the high-order silane-containing solution is held on the substrate table 203 in the film forming chamber 201, an inert gas is introduced into the film forming chamber 201 by an inert gas flow meter 204, and the substrate may be added as necessary. Evaporate the organic solvent from the solution on 202. The evaporated organic solvent is discharged through the exhaust system 205. High-order silane is decomposed by heating in the film forming chamber 201 to deposit a silicon film on the substrate 202.

In the examples of FIGS. 1 and 2, the coating of the solution on the substrate was carried out by using a spin coater having a rotation speed of 100 to 6000 RPM and a holder diameter of 200 mm, which can be replaced with a commercially available inert gas. The solution is applied onto the substrate by holding the substrates 102 and 202 on a spin coater, dropping a predetermined amount of the solution, and rotating the substrate at a predetermined rotation speed for a predetermined time.

The composition of the high-order silane-containing solution used in the examples is shown in Table 1. After examining the structures of the films obtained in Examples and Comparative Examples by X-ray diffraction, the following physical properties of the a-Si film were measured and the results are shown in Table 2. Performed under light irradiation of the optical electric conductivity ... AM-1.5,100mW / cm ^2, the electric conductivity of the Al deposition was measured by forming a coplanar type cell. Optical gap: Determined as the cut edge of the √αhν-hν plot from the light absorption coefficient α.

Example 1 No. 1 in Table 1 (hereinafter the same) as a high-order silane-containing solution. The composition shown in FIG. 1 was used as the experimental apparatus. As the substrate 102, 7059 glass manufactured by Corning Co., Ltd. is used, and the solution No. 1 drop on a few ml substrate 102, 1000
The coated film was formed by rotating at RPM for 3 seconds and then at 3000 RPM for 10 seconds. Next, the substrate 102 is placed on the substrate table 103 in the film forming chamber 101, and the temperature of the substrate table 103 is set to 150 ° C. while flowing hydrogen gas at 500 CCM from the inert gas flow meter 104, and then the deuterium lamp is used. Ultraviolet light was irradiated from 106 through the light irradiation window 107 for 40 minutes to carry out photopolymerization of the higher order silane to form a silicon film on the substrate 102.

Example 2 No. 1 as a high-order silane-containing solution. Use the composition of 1
The device shown in FIG. 2 was used as an experimental device. Board 20
As the No. 2 solution, 7059 glass manufactured by Corning Co., Ltd. was used. First, the solution No. Number 1
The solution was dropped on the ml substrate 202 and rotated at 1000 RPM for 3 seconds and then at 3000 RPM for 10 seconds to form a coating film. Next, the substrate 202 is placed on the substrate table 203 in the film forming chamber 201, and the inert gas flow meter 204 supplies hydrogen gas to 500
After flowing the CCM and setting the temperature of the substrate table 203 to 350 ° C., it is held for 50 minutes to carry out thermal polymerization of the higher silane,
A silicon film was formed on the substrate 202.

Example 3 No. 3 as a high-order silane-containing solution. Using the composition of 2,
Coating film formation with a spin coater at 1000 RPM for 5 seconds,
Next, except rotating at 3000 RPM for 15 seconds,
A silicon film was formed in the same manner as in Example 1.

Example 4 No. 4 as a high-order silane-containing solution. Using the composition of 2,
Coating film formation with a spin coater at 1000 RPM for 5 seconds,
Next, except rotating at 3000 RPM for 15 seconds,
A silicon film was formed in the same manner as in Example 2.

Embodiments 5, 7, 8, 10, 11, 15, 1
No. 6 as a high-order silane-containing solution 3,5,6,8,9,1
A silicon film was formed in the same manner as in Example 1 except that the compositions of 1 and 12 were used.

Example 12 No. 6 as a high-order silane-containing solution. A silicon film was formed in the same manner as in Example 2 except that the composition of 9 was used.

Examples 6, 9, 13, 17 No. 6 as a high-order silane-containing solution. A silicon film was formed in the same manner as in Example 3 except that the compositions of 4, 7, 10, and 13 were used.

Example 14 No. 6 as a high-order silane-containing solution. A silicon film was formed in the same manner as in Example 4 except that the composition of 10 was used.

Example 18 Using quartz glass as the substrate 102, the temperature of the substrate stage 103 was maintained at 150 ° C. for 10 minutes while irradiating the substrate on which the coating film was formed with ultraviolet light, and then the temperature was further increased by 10 ° C./min. A silicon film was formed in the same manner as in Example 1, except that the temperature was maintained at 550 ° C. for 40 minutes, and the temperature was further held at 550 ° C. for 20 minutes to continue irradiation with ultraviolet light. The photo-electric conductivity of the obtained film was 3.1 × 10 ^-4 S / cm, which was about the same as that of the conventional film (about 10 ^-4
S / cm).

Example 19 Quartz glass was used as the substrate 202, and the substrate on which the coating film was formed was heated at a temperature of the substrate table 203 of 350 in the thermal polymerization.
A silicon film was formed in the same manner as in Example 2, except that the temperature was kept at 30 ° C. for 30 minutes, the temperature was further raised to 550 ° C. for 40 minutes, and the temperature was further held at 550 ° C. for 20 minutes. Photoelectric conductivity of the obtained film was 1.1 × 10 ⁻⁴ S / cm.
And was equivalent to the conventional film (about 10 ⁻⁴ S / cm).

Example 20 A silicon film was formed in the same manner as in Example 1 except that a 3-inch diameter silicon single crystal substrate having a 100 nm thermal oxide film formed thereon was used as the substrate 102. After taking out the substrate 102, source and drain electrodes are formed by Al vapor deposition, and the channel length is 100 μm and the channel width is 200 μm.
m thin film transistor was prepared. The characteristics of the obtained transistor were measured, and the field effect mobility was electron mobility of 2.1 cm ² / Vs.
It was equivalent to FT (about 2 cm ² / Vs).

Example 21 A silicon film was formed in the same manner as in Example 3 except that a 3-inch diameter silicon single crystal substrate having a 100 nm thermal oxide film formed thereon was used as the substrate 102. After taking out the substrate 102, source and drain electrodes are formed by Al vapor deposition, and the channel length is 100 μm and the channel width is 200 μm.
m thin film transistor was prepared. When the characteristics of the obtained transistor were measured, the field effect mobility was an electron mobility of 64 cm ² / Vs, which was equivalent to that of a conventional polysilicon TFT (about 50 cm ² / Vs).

According to the X-ray diffraction measurement in the above examples, in Examples 1 to 17 and 20, a-Si was used as the silicon film.
A film, a polysilicon film was obtained in Examples 18, 19 and 21. The particle size of polysilicon is about 4 to 5 μm,
The film thickness was about 50 nm.

Comparative Example Using a commercially available plasma CVD apparatus, using monosilane as a reaction gas, under a pressure of 0.1 torr and a substrate table temperature of 200.
Plasma CVD was performed for 5 minutes at a high-frequency output of 20 W of 13.56 MHz at a temperature of ℃, and an a-Si film was deposited to a thickness of 80 nm.

[0034]

[Table 1]

As is clear from Table 2, the a-Si film formed according to the present invention has the same or superior photoconductivity as the film obtained by the plasma CVD method.

[Table 2]

[0036]

As described above, according to the present invention, the higher order silane represented by the general formula Si _n H _{2n + 2} (where n is an integer of n ≧ 2) is mixed with the organic solvent at a constant ratio. A high quality silicon film can be uniformly formed with high safety by applying a solution dissolved in the substrate on the substrate and then decomposing it to form a silicon film on the substrate. When a silicon film is formed using the high order silane-containing solution of the present invention, since a liquid raw material is used,
Unlike the general CVD method, the device is easy and powder generation can be prevented. Further, a high-quality silicon film can be efficiently and safely formed on a large-area substrate, which was difficult by the conventional CVD method. Further, since a complicated and expensive reaction device is not required, there is an advantage that the facility cost in the semiconductor material device can be made extremely small. From the above, the high-order silane-containing solution of the present invention can be widely used for forming a silicon film such as an LSI as a silicon film application device, a thin film transistor, a photoelectric conversion device, and a photoconductor, and is a breakthrough in the application field of the silicon film. Expect expansion.

[Brief description of drawings]

FIG. 1 is an apparatus for forming a silicon film by photopolymerization by ultraviolet irradiation.

FIG. 2 is an apparatus for forming a silicon film by thermal polymerization by heating.

[Explanation of symbols]

 101, 201 Reaction chamber 102, 202 Substrate 103, 203 Substrate stand 104, 204 Inert gas flow meter 105, 205 Exhaust system 106 Deuterium lamp 107 Light transmission window

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Keiji Kawasaki 5-1, Ogimachi, Kawasaki-ku, Kawasaki-shi, Kanagawa Showa Denko K.K.

Claims (2)

[Claims] 1. A high-order silane-containing solution for forming a silicon film, wherein a high-order silane represented by the general formula Si _n H _{2n + 2} (where n is an integer of n ≧ 2) is dissolved in an organic solvent. The total high-order silane concentration in the solvent (total high-order silane weight / (total high-order silane weight + solvent weight) × 100) is 0.1 to 50% by weight, and C _a H _b as an organic solvent (where a is 3 ≦ a ≦
16, b is 8 ≦ b saturated hydrocarbons represented by ≦ 34 integer), unsaturated hydrocarbons, aromatics or C _d H _e O
_f (however, d is 2 ≦ d ≦ 16, e is 6 ≦ e ≦ 34, and f is 1
A high order silane-containing solution for forming a silicon film, characterized by using an ether represented by ≦ f ≦ 3) or a mixed solvent thereof. 2. A method for forming a silicon film, which comprises applying the solution according to claim 1 and applying energy such that high-order silane is decomposed.