JPH04130059A - Production of silicon carbide-based pipe and silicon dioxide-silicon carbide combined pipe - Google Patents

Abstract

PURPOSE:To simply and inexpensively obtain a high purity silicon carbide-based pipe suitable for use as a heat resistant pipe for producing a semiconductor by forming a porous body of quartz glass on the surface of a tubular substrate by a vapor phase synthesis method, depositing carbon in the porous body by a vapor thermal decomposition method and carrying out calcination. CONSTITUTION:A porous body of quartz glass is formed on the surface of a tubular substrate such as a high purity graphite pipe or a high purity quartz glass pipe by a vapor phase synthesis method. Carbon formed by thermally decomposing gas contg. gaseous hydrocarbon such as methane or gaseous halogeneted hydrocarbon such as CH3Cl is deposited in the porous body by such an amt. as to regulate the molar ratio of carbon to silicon dioxide to >=3. Calcination is then carried out at about 1,600-2,500 deg.C to obtain a silicon carbide-based pipe. This pipe can be made dense by impregnating molten high purity silicon.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing silicon carbide tubes and silicon dioxide-silicon carbide composite tubes, and more specifically to process tubes used in semiconductor manufacturing processes. The present invention relates to a method for manufacturing a silicon carbide tube and a silicon dioxide-silicon carbide composite tube that are tubular, have high purity and heat resistance, and are used as materials for liner tubes and the like.

Conventionally, heat-resistant pipes (process tubes, liner tubes) for semiconductor manufacturing, which require high purity, have mainly been made of high-purity quartz glass. Pipes made of quartz glass have the advantage of being easily available in high-purity products and having translucency, which allows the inside of the pipe to be observed, and have been widely used for heat treatment of semiconductors. However, this quartz glass pipe has 1000
Deformation due to viscous flow begins to occur at temperatures exceeding 1°C.
It is hardly used for heat treatment at 150°C or higher.

On the other hand, silicon carbide pipes are considered promising for heat treatment in such high temperature ranges.

Silicon carbide is said to have been discovered by E. G. Acheson in 1981, and the world's first industrial manufacturing method for silicon carbide was the Acheson method, which synthesized silicon carbide from silica stone and coke using the in-phase reaction formula (1) shown below. It has been established as a.

SiO□+3C-SiC+2CO (1) In recent years, in the process of manufacturing semiconductors such as LSI, silicon carbide-based materials have been used as core tubes and wafer support members when heat-treating Si sea urchins at high temperatures exceeding 110D'C. The proportion of heat-resistant materials used is increasing. However, with the increase in the degree of integration of LSIs and the like, the adverse effects of trace impurities contained in the reactor core tube and wafer support members on wafers have become a problem.

In the above-mentioned Acheson method, silica stone, silica sand, quartz powder, coroiglusilica, etc. are used as silicon sources, and coke, cool pitch, carbon black, etc. are used as carbon sources and are physically mixed, and then these mixtures are fired to produce silicon carbide-based materials. It is used as a raw material. For this reason, due to metal impurities contained in the silicon source and carbon source and impurities contained in the sintering aid added to promote densification during firing, impurity metal elements ranging from several 110PP to several percent The silicon carbide-based heat-resistant material contained. Due to the strict requirements for silicon carbide raw materials, the manufacturing method of silicon carbide raw material powder by vapor phase synthesis method has also been industrialized. An S1 impregnation method that does not use a binder has also been proposed (Japanese Patent Laid-Open No. 57-4
Publication No. 3553).

However, even if high-purity silicon carbide raw material powder synthesized by the gas phase method described in the above-mentioned prior art is used, it is difficult to store this high-purity silicon carbide raw material powder or to transfer the silicon carbide powder to pipes. Contamination occurs from containers, tools, or the atmosphere when molding into shapes or firing molded products. The manufacturing process for silicon carbide-based materials is thus complex, and there is a risk of contamination in each process. Therefore, even if high-purity silicon carbide raw material powder synthesized by the vapor phase method is used, it is still high enough for semiconductor manufacturing. There was a problem in that it was difficult to manufacture pure silicon carbide pipes.

Only when forming a dense thick film of silicon carbide directly on a high-purity graphite vibrator or a high-purity quartz glass pipe using the vapor phase growth method, it is possible to manufacture a silicon carbide-based pipe of considerably high purity. can.

However, when using this manufacturing method, the growth rate of the silicon carbide material is slow, the manufacturing cost is high, and furthermore, there are problems such as failure due to mismatch in thermal expansion coefficient between the base material graphite or quartz and the silicon carbide material. There were also issues, and there was still a long way to go before it could be put into practical use.

The present invention was invented in view of the above-mentioned problems, and
When synthesizing silicon carbide, an ultra-high purity synthetic silica glass porous body is deposited on the outer or inner surface of a high-purity graphite pipe or high-purity quartz glass pipe, and this is used as a silicon source to manufacture high-purity semiconductors. It is an object of the present invention to provide a method for producing silicon carbide tubes and silicon dioxide-silicon carbide composite tubes, which are excellent as equipment materials, through a simple process and at low cost.

Steps to Solve the Problems In order to achieve the above object, a method for manufacturing a silicon carbide tube according to the present invention involves forming a porous body of quartz glass on the surface of a tubular base material by vapor phase synthesis, and It is characterized in that carbon produced by thermal decomposition of a gas containing hydrocarbon gas or halogenated hydrocarbon gas is deposited in a porous body, and then fired.

Further, in the method for manufacturing the silicon carbide tube described above, the carbon precipitated in the porous silica glass body is set to a carbon/silicon dioxide molar ratio of 3 or more, and the firing is performed at a temperature of 1600°C or more and 2500°C or less. It is a feature.

Further, the present invention is characterized in that the silicon carbide tube manufactured by the above method for manufacturing a silicon carbide tube is further filled with metallic silicon.

Furthermore, in the method for manufacturing a silicon dioxide-silicon carbide composite tube, a porous body of quartz glass is formed on the surface of the tubular base material by vapor phase synthesis, and a hydrocarbon gas or a halogenated hydrocarbon is contained in the porous body of quartz glass. Carbon produced by thermal decomposition of a gas containing gas is precipitated, and the carbon precipitated in the silica glass porous body has a carbon/silicon dioxide molar ratio of 1.
It is characterized in that the temperature is as follows, and then firing is performed at a temperature of 1600° C. or higher and 2000° C. or lower.

Hereinafter, the method for manufacturing a silicon carbide tube and a silicon dioxide-silicon carbide composite tube according to the present invention will be explained in more detail.

The manufacturing method for ultra-high purity synthetic quartz glass is MCV D.
(Modified Chemical Vapor
Deposition), ○ V D (O
utside Vapor Deposition
), VAD(~1apor-phase A
Technologies collectively known as the soot method, such as the xial deposition method, were developed for purposes such as optical fiber manufacturing.
It has been put into practical use.

The OVD method is a method in which synthetic quartz glass fine particles are deposited on the outside of a tube or rod as a starting material (the MCVD method is a method in which fine particles of synthetic quartz glass are deposited on the inside of a tube as a starting material). By using the above-mentioned OVD or MCVD method and directly shaping the silicon source (silicon dioxide), which is the raw material for silicon carbide, into a pipe shape, it is possible to avoid contamination due to handling during the molding process, etc., and achieve high purity. A silicon carbide-based material can be obtained.As the starting tubular base material, high-purity materials such as quartz glass pipes and graphite pipes are suitable.

A porous body of silica glass synthesized in a vapor phase is produced by vaporizing silicon chloride such as silicon tetrachloride and performing the reactions (water splitting reaction (2) or oxidation reaction (3) shown below in 2) in an oxidizing atmosphere such as a fire.
It is manufactured by depositing the produced silicon dioxide fine particles.

SIC flood 4 +2H20−−−→ 5i(h+4HCj
(2) SiC +0□ --w 5iO7+
2Cj, (3) The vapor-phase synthetic silica glass porous body produced in this way is coated with HCQ at the stage of depositing fine particles.
, C10 and other halogen gases, it is possible to prevent the contamination of impurity metal compounds that are produced when the halogen gases corrode the synthesis container, resulting in extremely high purity silicon dioxide.

The present inventors have demonstrated that by heat-treating a porous body of synthetic quartz glass in an atmosphere containing high-purity hydrocarbon gas or halogenated hydrocarbon gas, carbon is uniformly deposited inside the porous body of synthetic quartz glass. Taking into account precipitation, if the pipe-shaped silicon dioxide-carbon composite obtained by the above heat treatment is fired, it will be extremely pure due to the high purity of the starting raw material and the absence of mixing and molding steps. We have discovered that it is possible to synthesize highly porous silicon carbide pipes.

Next, the porous silicon carbide pipe is heated above the melting point of silicon and immersed in molten silicon under a reduced pressure atmosphere for reaction sintering, or the porous silicon carbide pipe is heated to a temperature above the melting point of silicon, or the porous silicon carbide pipe is heated to a temperature higher than the melting point of silicon, and then immersed in molten silicon under a reduced pressure atmosphere for reaction sintering. 5iCf! −,5iHCfi3
A dense silicon carbide pipe can be easily obtained by heat treatment at a temperature above the decomposition temperature of the used gas species and below 2000°C in a gas atmosphere consisting of at least one selected from , SiH4, etc. I found out that it is possible.

A pipe-like synthetic quartz glass porous body of ultra-high purity is used as SiO□ (silicon dioxide) in the above formula (1), and heat treatment is performed in an atmosphere containing hydrocarbon gas or halogenated hydrocarbon gas. Carbon is uniformly deposited even inside the porous silica glass, and a silicon dioxide-carbon composite similar to that obtained by microscopically mixing silicon dioxide and carbon is obtained. By firing this pipe-shaped silicon dioxide-carbon composite, a highly pure porous silicon carbide pipe can be obtained.

Hydrocarbon gases include C14, C2H6, CaHa,
C4H+.

C2H,, C2H2, C6H6, CHaCJ, CILC12, CHCQ as halogenated hydrocarbon residue 3.
CJ4Cn 2. CJ3C13, (1,2H3Cj
C2H2Ci! 2. C2HCj3. C6H3 (j!
Carbon precipitation due to thermal decomposition does not occur below the decomposition temperature of hydrocarbon gas or halogenated hydrocarbon gas, and on the other hand, at temperatures above 1400°C, the porous body of synthetic quartz glass becomes densified. Carbon precipitation inside the porous body becomes impossible. Therefore, the carbon precipitation temperature needs to be in the range from the decomposition temperature of hydrocarbon gas or halogenated hydrocarbon gas to 1400° C. or less. By controlling the carbon precipitation conditions, silicon dioxide-carbon composites having various carbon molar ratios (C to Si02 molar ratio) can be obtained.

From the thermodynamic calculation results shown in Figure 1, the standard free energy (△G°) in equation (1) is negative as shown in Fig. 1. It can be seen that the starting temperature, that is, approximately 1600°C or higher is required.On the other hand, since a heating device that achieves a temperature condition in which the firing temperature exceeds 2500°C is not practical, the firing temperature when producing silicon carbide is set at 1600°C. ~2500℃
A range of is desirable.

The silicon carbide produced is a difficult-to-sinter substance and does not become dense like quartz glass, so it cannot maintain the porous shape unless there is excess carbon. Therefore, in order to obtain a porous silicon carbide pipe, it is necessary that the carbon molar ratio is 30 or more.

At this time, if the firing temperature is set to 2000° C. or higher, the synthetic quartz glass used as the base material can be volatilized as silicon monoxide.

Another possible method for the disappearance of the synthetic quartz glass substrate is dissolution with an aqueous hydrogen fluoride solution, and another possible method for the disappearance of the graphite substrate is heating in an oxidizing atmosphere.

The porosity of porous silicon carbide synthesized in this way can be controlled by controlling the temperature of the deposition surface during precipitation of the synthetic quartz glass porous body and by heat treating the precipitated synthetic quartz glass porous body. It can be controlled by performing the above two processes after doing this.

Finally, the porous silicon carbide pipe is impregnated with molten high-purity silicon to form a dense silicon carbide pipe. At this time, it is desirable that the atmosphere in the heating furnace be in a reduced pressure state in order to allow the molten silicon to quickly penetrate into the porous body. Further, the temperature in the heating furnace is preferably higher than the excitation of silicon and within a temperature range in which silicon is difficult to evaporate.

By infiltrating silicon into the porous body of the silicon carbide pipe, excess carbon and silicon constituting the porous body can be converted into silicon carbide through the reaction of equation (4) shown below.

Si+CSiC (4) Alternatively, a porous silicon carbide pipe can be used for silicon-containing gas,
For example, the porous silicon carbide material is heated in a gas atmosphere consisting of at least one selected from 5xCj4.5iHCj3, SiH4, etc., at a temperature above the decomposition temperature of the gas species used and below 2000°C. Metallic silicon is deposited even inside the pipe. Furthermore, hydrogen, argon, or the like may be used as a carrier gas. At this time, precipitation of metallic silicon does not occur below the decomposition temperature of the gas species used, and at temperatures exceeding 2000°C, large amounts of energy are required and uneven precipitation occurs near the surface of the porous silicon carbide pipe. For this reason, it is more preferable to use 600~
It is preferable to process under mild conditions of 1200°C. At this time, excess carbon present in the silicon carbide pipe is very fine particles of several tens of nanometers, so molten silicon and silicon-containing It is easily converted into silicon carbide by gas or precipitated metallic silicon, and the strength of the silicon carbide material is improved.

In addition, when the carbon molar ratio of the above-mentioned pipe-shaped silicon dioxide-carbon composite is 10 or less,
When fired in a temperature range below ℃, the SiC production reaction shown in equation (1) occurs, and sintering progresses due to the viscous flow of excess quartz glass, forming a dense pipe-shaped silicon dioxide-silicon carbide composite. is obtained. If the carbon molar ratio at this time is more than 1.0 and less than 30, the precipitated carbon will disturb the viscous flow of the silica glass and cannot be densified, resulting in the formation of powdered silicon carbide. The shape of the porous body cannot be maintained. Therefore, in order to obtain a dense pipe-shaped silicon dioxide-silicon carbide composite, the carbon molar ratio is 1.
It needs to be 0 or less. The upper limit of the firing temperature needs to be 2000° C. or lower at which volatilization of the quartz glass does not occur.

According to the above-described method for manufacturing a silicon carbide tube according to the present invention, a porous body of high-purity pipe-shaped synthetic quartz glass is heat-treated in an atmosphere containing hydrocarbon gas or halogenated hydrocarbon gas. , carbon is uniformly precipitated inside the porous body of the pipe-shaped synthetic quartz glass, and the resulting pipe-shaped silicon dioxide-carbon composite having a carbon molar ratio of 3.0 or more is heated at 16 DO to 25 DO When fired, a porous silicon carbide pipe of extremely high purity is produced due to the high purity of the starting materials and the absence of mixing and molding steps.

Furthermore, if the porous silicon carbide vibrator described above is heated together with high-purity silicon in a reduced pressure atmosphere to a temperature higher than the melting point of silicon, the molten high-purity silicon will penetrate into the inside of the porous body, forming a dense silicon carbide vibrator. A vibrator is manufactured.

Alternatively, by heat-treating a porous silicon carbide vibrator in a silicon-containing gas atmosphere at a temperature above the decomposition temperature of the gas species used and below 2000°C, metallic silicon is deposited even inside the porous molded body. is carried out, and a dense silicon carbide vibe is manufactured.

In addition, pipe-shaped silicon dioxide with a carbon molar ratio of 1.0 or less
If a carbon composite is fired in a temperature range of 1,600° C. or higher and 2,000° C. or lower, a dense pipe-shaped silicon dioxide-silicon carbide composite with extremely high purity can be obtained for the same reason as described above.

EXAMPLES AND COMPARATIVE EXAMPLES Examples and comparative examples of the method for manufacturing silicon carbide pipes and silicon dioxide-silicon carbide composite pipes according to the present invention will be described below.

[Example 1] The outer surface of a high-purity synthetic quartz glass pipe with an outer diameter of 190 mm was coated with a bulk density of about 0.3 g/am3 by the OV D method.
, fine silica glass particles having a specific surface area of about 12 m''/g and an average particle size of about 0.02 μm were precipitated.Next, the pipe-shaped porous body of synthetic quartz glass on which the fine quartz glass particles had been precipitated was heated with C.
500°C to 150°C in an atmosphere of 100% H, gas
Heat treatment was performed in a temperature range of 0° C. for 4 hours. As a result, as shown in Table 1 below, in the temperature range of approximately 600°C to 1400°C, which is the decomposition temperature of CH4 gas, carbon precipitates even inside the porous body of synthetic silica glass, and silica glass fine particles become carbonized. A coated pipe-shaped silicon dioxide-carbon composite could be obtained.

However, thermal decomposition of CH4 gas does not occur at 500℃,
At 1500° C., the synthetic quartz glass became densified during the process of increasing the temperature to the treatment temperature, and carbon was only deposited on the outer surface of the porous body of the synthetic quartz glass.

Of these, the molar ratio of silicon dioxide to carbon in the silicon dioxide-carbon composite when treated at 1000°C is 1.8
．． It was 5.

A pipe-shaped synthetic quartz glass-carbon composite treated at 1000°C in the above method was heated to 1500°C under reduced pressure.
When baked for 3 hours in the temperature range of ~2000℃, the second
From the X-ray diffraction results shown in the figure, it was confirmed that β-type silicon carbide was formed at a temperature of 1600° C. or higher.

This porous silicon carbide pipe has an impurity metal element concentration of IP
Pm or less, making it an extremely pure silicon carbide material.

When the pipe-shaped silicon dioxide-carbon composite described above was fired at 2D00°C for 3 hours in a reduced pressure atmosphere, the silica glass used as the base material disappeared and the bulk density was approximately 0.3.
g/cm3. A carbon-excess porous silicon carbide pipe with a porosity of about 46% and a molar ratio of carbon to silicon carbide of about 5.5 was obtained.

Next, this porous silicon carbide pipe was heated under a reduced pressure atmosphere for 16 minutes.
When it was immersed in molten silicon in a graphite crucible coated with silicon carbide at a temperature of 00°C, the silicon permeated into the inside of the porous body, making it possible to obtain a dense silicon carbide pipe.

[Example 21] The outer surface of a high-purity synthetic quartz glass pipe with an outer diameter of 190 mm was prepared by the OVD method (silica glass fine particles having a bulk density of about 03 g/cm3, a specific surface area of about 12 m27 g, and an average particle size of about 0.2 tim). Next, this pipe-shaped synthetic quartz glass porous body was heated with 40% CH4 gas and 6% Ar gas.
When heat treatment was performed at 1000°C for 30 minutes in a 0% atmosphere, carbon was precipitated even inside the pipe-shaped porous body of synthetic quartz glass, and the pipe-shaped silicon dioxide -
A carbon complex was obtained. The molar ratio of silicon dioxide to carbon at this time was 1.05.

The pipe-shaped silicon dioxide-carbon composite described above
When heated in the temperature range of 0°C to 2200°C, as shown in Table 2 below, silicon carbide does not form at 1500°C, and SiO, a volatile product of silica glass, forms at temperatures exceeding 2000°C. Significant bubble formation due to gas;
It did not become a dense material.

The pipe-shaped silicon dioxide-silicon carbide composite fired at 1800°C for 13 hours in a reduced pressure atmosphere is almost completely densified, with an inner diameter of 190mm, a thickness of 6mm, and a length of 20mm.
When the pipe was heated at 1200°C for 24 hours, the amount of deformation of the inner diameter was 11 or less.

(Leaving space below) Table 1. According to the method for manufacturing a silicon carbide pipe according to the present invention, ultra-high purity pipe-shaped porous synthetic quartz glass and vapor-phase pyrolytic carbon are produced in the same phase. Since silicon carbide is synthesized through a reaction, it is possible to obtain pipe-shaped porous silicon carbide with extremely high purity.
By infiltrating this pipe-shaped porous silicon carbide with silicon, a highly pure and dense silicon carbide pipe can be obtained.

Furthermore, by firing at a carbon deposition molar ratio of 10 or less, a highly pure and dense silicon dioxide-silicon carbide composite tube can be obtained.

Therefore, silicon carbide tubes with high purity and high strength are suitable for manufacturing semiconductor manufacturing jigs, such as heat-resistant jigs such as process tubes and liner tubes used in thermal diffusion processing of silicon wafers. It can be provided through a simple process and at low cost.

[Brief explanation of drawings]

FIG. 1 is a graph showing the standard free energy calculation results for the reaction in equation (1) above, and FIG. 2 is a graph showing the relationship between heat treatment temperature and silicon carbide production range. Agent for patent applicant Sumitomo Metal Industries, Ltd.

Claims (4)

[Claims] (1) A porous body of quartz glass is formed on the surface of a tubular base material by vapor phase synthesis, and carbon is generated by thermal decomposition of a gas containing hydrocarbon gas or halogenated hydrocarbon gas in the porous body of quartz glass. 1. A method for producing a silicon carbide tube, which comprises precipitating and then firing. (2) Claim 1 characterized in that the carbon precipitated in the porous body of quartz glass has a carbon/silicon dioxide molar ratio of 3 or more, and the firing is performed at a temperature of 1600°C or more and 2500°C or less.
A method of manufacturing the silicon carbide pipe described above. (3) A method for manufacturing a silicon carbide tube, comprising filling the silicon carbide tube according to claim 1 or 2 with metallic silicon. (4) A porous body of quartz glass is formed on the surface of a tubular base material by vapor phase synthesis, and carbon is generated by thermal decomposition of a gas containing hydrocarbon gas or halogenated hydrocarbon gas in the porous body of quartz glass. and the carbon precipitated in the silica glass porous body at a carbon/silicon dioxide molar ratio of 1.
A method for producing a silicon dioxide-silicon carbide composite tube, characterized in that the following is followed, and then firing is performed at a temperature of 1600°C or higher and 2000°C or lower.