JPH062947B2 - Method for forming silicon carbide thin film - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention relates to the formation of a silicon carbide (SiC) thin film used in, for example, a jig for high temperature, a mechanical seal having heat resistance and corrosion resistance, or a heating table for a silicon wafer for semiconductors. The present invention relates to a method for forming a member on a carbon or carbide base material, a ceramics, a metal having a relatively high heat resistance, or an alloy base material by using a CVD method.

(Prior Art) As a method for forming a carbide film, a vapor phase reaction, that is, a CVD method is known. The CVD method is a method in which a constituent element of a film is made into a compound that is easily vaporized, this is introduced into a reaction system by a carrier gas, and a solid layer generated by a chemical reaction of the reaction gas is deposited on a substrate to form a film. . This CVD
When a silicon carbide film is formed on carbon (graphite) or a carbide substrate by the method, the inside of the reaction furnace is conventionally replaced with nitrogen gas and exhausted, and then glow is generated by alternating current between the rod-shaped graphite substrate and the electrode. Discharge, then heat the substrate to 1400 ℃ and heat the tetramethylsilane at a constant flow rate (eg 2.8 × 10
^-4 mol / min) to supply into the glow discharge plasma to form a silicon carbide thin film.

According to this conventional method, the silicon carbide thin film is at most 3.75μ.
It is not possible to form a lump at a deposition rate of about m / min.

(Problems to be Solved by the Invention) The present invention intends to provide a method for forming a silicon carbide thin film, which is capable of forming a silicon carbide thin film at a higher speed than in the past and which is capable of obtaining a dense and highly hard thin film. It is a thing.

(Means for Solving the Problems) In order to achieve this object, the method for forming a silicon carbide thin film of the present invention is to install a base material in a reaction furnace and heat the base material in the furnace or to energize or electromagnetic induction. It is heated by the action, and the chemical formula Si (CH ₃ ) _x Cl
A gas of an organic silicon compound of _y H _z (however, x + y + z = 4, x ≠ 0) is supplied, glow discharge is generated near the base material, and a laser beam, plasma jet, or microwave is irradiated near the base material. CVD by heating and activating the raw material gas to decompose and condense the organosilicon compound
The method is characterized in that a silicon carbide thin film is formed on the surface of the substrate by the method.

(Embodiment) An embodiment of the present invention will be described below with reference to FIG. The graphite base material 2 is put into the reaction furnace 1, and the inside of the reaction furnace 1 is exhausted and recovered by a device 3
0 (This device includes a vacuum pump 34, a manual valve 31, a cold trap 32, a chemical trap 33,
Methane sensor 18C) and the raw material and carrier gas supply device described later to replace with argon gas and evacuate to 1 mPa. While heating while energizing, a glow discharge power source 4 (AC2000V, 20mA) causes glow discharge between the base material 2 and the glow discharge annular electrode 5 to generate a plasma gas, thereby generating a reaction gas (raw material). A laser beam 10 generated by activating a gas and a gas generated by its decomposition and condensation, and generated by a laser device 6 such as a carbon dioxide gas laser (200 V).
To 20 × 0.15 mm with the cylindrical lens 7,
Through the potassium chloride window 8 provided in the reaction furnace 1, the space 9 between the annular electrode 5 and the substrate 2 in which glow discharge is being generated is irradiated to generate a high temperature, and part of it is opposite to the window 8. A silicon carbide thin film is formed on the base material 2 by the CVD method by being reflected by the reflection mirror 11 and guided to the space 9 again through the side window 8 '. The laser beam output is monitored by the power meter 12, the temperature of the substrate 2 is monitored by the thermocouple 28, and the pressure in the reactor 1 is monitored by the pressure gauge 29.

Argon gas is used as the carrier gas, and the argon gas is supplied to the reaction furnace 1 by the argon gas pressure vessel 1.
3 from the deoxidizer 15A of the carrier gas supply line 14
The flow rate is adjusted by the flow rate adjuster 17A through the cock 27, the cock 27, and the dehydrator 16A, and the oxygen analyzer 18
Gas is supplied while monitoring each measurement value of A and the flow meter 19A.

On the other hand, the raw material gas is supplied from a raw material container 20 containing a mixed liquid of dimethyldichlorosilane and carbon tetrachloride by a metering pump 21 into a vaporization chamber 22 which is an adiabatic container, and vaporized from the vaporization chamber 22. A conduit 2 having a heat insulating layer for merging the mixed gas of dimethyldichlorosilane and carbon tetrachloride thus formed with the gas from the carrier gas supply conduit 14.
It is supplied into the reaction furnace 1 via 3, 24.

The raw material container 20 and the vaporization chamber 22 are filled with a carrier gas via pipe lines 25 and 26, respectively.
In the pipe line 26 to 2, the flow controller 17B and the flow meter 19B are provided.
And are provided to monitor and adjust the flow rate. That is, a mixed gas of vaporized dimethylchlorosilane, carbon tetrachloride and argon is introduced into the reaction furnace 1 through the pipe 24 by the operation of the flow rate regulators 17A and 17B, the cock 27, etc. The partial pressure of the raw material gas inside is the temperature of the vaporization chamber 22 controlled by the electronic constant temperature bath, the dropping rate of the raw material gas,
It was adjusted by changing the argon flow rate in the vaporization chamber 22 and the argon gas flow rate measured by the flow meter 19A.

Specifically, the temperature in the reaction furnace 1 is controlled within the range of 1200 to 1500 ° C., and the dropping rate of the raw material liquid into the vaporization chamber 22 is 0.1 to 1
irradiation with the laser beam 10 and glow discharge under conditions of ml / min and an argon gas flow rate of 0.1 to 2.5 / min.
The reaction was performed while electrically heating the base material 2.
For example, the reaction furnace temperature is 1380 to 1420 ° C., the dripping rate of the mixed liquid of dimethyldichlorosilane and carbon tetrachloride (molar ratio 1: 1) into the vaporization chamber 22 is 0.0029 mol / min, and the flow rate of the argon gas into the vaporization chamber 22 is Is 0.05 / min, the vaporization temperature is 100 ° C., and the argon gas flow rate in the argon gas supply line 14 is 0.5 / m.
By pyrolyzing for 1 hour under the condition of in (namely, diluted 10 times), a β-type silicon carbide thin film having a Vickers speed of 3000 and a thickness of 0.3 mm was formed on the surface of the graphite base material 2 having a diameter of 17 mm. Further, according to the cross-sectional photograph of the formed thin film, it was confirmed that the thin film was dense. At this time, the average formation rate of the thin film was 5 μm / min even when the pressure in the reaction furnace 1 was 10 ⁻² Torr or less, and it was possible to greatly improve the formation rate as compared with the conventional case.

As described above, the laser beam causes a photolytic reaction in the vicinity of the base material 2, a high temperature region is formed, and a glow discharge is caused to act in the vicinity of the base material 2, whereby the reaction proceeds at high speed. Further, the thinning of the raw material is promoted. That is, organic silicon decomposes and condenses to form a silicon carbide thin film, but when the supply amount increases, decomposition and condensation cannot be completed in time, and in the case of having a methyl group, elimination of the methyl group becomes incomplete. For this reason, the methyl groups trapped between the silicon carbide particles eventually become free carbon and precipitate between the silicon carbide particles. To prevent this free carbon precipitation,
It is sufficient to promote decomposition and condensation. When glow discharge is applied, decomposition and condensation reaction of organic silicon are promoted, free carbon deposition is prevented, and a thin film having high hardness is formed. Further, the decomposition of organic silicon occurs at an arbitrary temperature, and as a result, not only a silicon carbide thin film but also a carbon thin film, silicon carbide ultrafine powder, and carbon powder are synthesized. By heating the raw material gas with the laser beam, it is rapidly heated to a target temperature for forming the silicon carbide thin film, and a dense thin film is formed.

The raw material gas used in the present invention has a chemical formula
Si (CH ₃ ) _x Cl _y H _z (provided that x + y + z = 4, x ≠ 0) a gas of an organic silicon compound such as chloromethylsilane, methyldichlorosilane, methyltrichlorosilane, dimethylchlorosilane, or trimethylchlorosilane is used. However, as shown in the figure, hydrogen, hydrocarbons (methane, benzene), etc. are fed from the pressure vessel 35 to facilitate decomposition of the source gas during self-decomposition or to prevent impurities such as silicon and carbon from being deposited. 27, the flow rate controller 17C adjusts the flow rate through the deoxygenation apparatus 15B of the supply pipeline 36 and the dehydration apparatus 16B, and the oxygen analyzer 18B.
And while monitoring each measurement value of the flow meter 19C, the reactor 1
It is supplied into the reaction furnace 1 from the inlet A of the.

FIG. 2 shows another embodiment of the present invention, in which a plasma torch 37 is provided in the space 9 between the glow discharge electrode 5 and the substrate 2.
(Or microwave irradiation cylinder) supplies a plasma jet (or microwave) to heat the reaction gas, irradiates the base material 2, and provides a coil 38 for high-frequency electromagnetic induction in the vicinity of the base material 2, The coil 38 is energized by a high frequency power source 39 to heat the substrate 2 by electromagnetic induction. If a plasma jet (or microwave) is used, activation of the reaction gas can be achieved similarly to the laser, and the deposition rate of silicon carbide can be increased.

(Effects of the Invention) As described above, according to the present invention, the reaction gas is heated near the substrate by laser beam, plasma jet, or microwave irradiation, and plasma is generated by glow discharge to activate it. Since the reaction is performed, the silicon carbide thin film can be formed on the base material at a higher speed than conventionally. Further, in the present invention, since the base material and the reaction gas can be efficiently heated and activated, compared with the case where the entire reaction furnace is heated, the base material and the vicinity of the base material and the vicinity thereof can be rapidly fed with a small amount of energy. The gas in the space is heated, and a dense and high-hardness thin film can be obtained as the target silicon carbide thin film.

Although the present invention refers to a method for forming a silicon carbide thin film, for example, when a base material such as graphite and the base material are stacked and bonded together, not only a film is formed on the surface but also a penetration into a bonding gap. As a result, a silicon carbide film is formed also on the facing joint surface, and finally both base materials are firmly bonded by the formed silicon carbide. Therefore, the present invention is also useful as a bonding method using silicon carbide. .

[Brief description of drawings]

FIG. 1 is an apparatus configuration diagram for explaining an embodiment of the method of the present invention, and FIG. 2 is a configuration diagram of a reaction furnace showing another embodiment of the present invention.

Claims (1)

[Claims] 1. A base material is placed in a reaction furnace, and the base material is heated in the furnace by heating, energization, or electromagnetic induction, and chemical formula Si (C
H ₃ ) _x Cl _y H _z (however, x + y + z = 4, x ≠ 0) is supplied to generate a glow discharge in the vicinity of the base material and generate a laser beam, a plasma jet or a microwave. C by the decomposition and condensation reaction of the organosilicon compound by irradiating the vicinity of the material to heat and activate the source gas.
A method of forming a silicon carbide thin film, which comprises forming a silicon carbide thin film on the surface of a substrate by a VD method.