JPH0532462A - Production of joint-formed silicon carbide formed article - Google Patents

Abstract

PURPOSE:To produce a formed article of high-purity silicon carbide having complicate form or large size and high strength at the joined part and, accordingly, useful as a heat-resistant jig such as process tube and wafer boat used in the thermal diffusion treatment of silicon wafer. CONSTITUTION:Porous articles of synthetic quartz glass are made to contact with each other at the bonding faces. Carbon produced by the thermal decomposition of a gas containing a hydrocarbon gas or halogenated hydrocarbon gas is deposited in the porous material and on the bonding faces at a carbon to silicon dioxide molar ratio (C/SiO3) of >=3.5 and the product is baked. Metallic silicon is impregnated into the obtained formed article of porous silicon carbide to obtain the objective joint-formed silicon carbide formed article.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a bonded silicon carbide molding, and more particularly to a semiconductor manufacturing jig, for example, a process tube or wafer boat used for thermal diffusion treatment of silicon wafers. The present invention relates to a method for manufacturing a silicon carbide-based molded article to be joined and formed, which is useful as a material for a heat-resistant jig such as.

[0002]

2. Description of the Related Art Conventionally, the problems to be solved by the invention
As a heat resistant jig for semiconductor manufacturing that requires high purity,
Those mainly made of quartz glass were used. The quartz glass jig has advantages that it is possible to easily manufacture a jig having extremely high purity, and that it is transparent because it is easy to observe the inside.

However, this quartz glass is 1000 ° C.
When the temperature exceeds 1150, deformation due to viscous flow begins to occur.
It has a drawback that it cannot be used for heat treatment at a temperature of ℃ or more, and that it has a short life such as devitrification and damage due to cristobalite formation.

In recent years, as a material capable of solving such drawbacks, a composite in which metallic silicon is filled in a porous silicon carbide compact formed by molding silicon carbide powder has been developed in place of quartz glass, and is used for semiconductor manufacturing. Used as a heat resistant jig. However, it is difficult to obtain a high-purity silicon carbide raw material powder, and the manufacturing process such as raw material blending, molding, purification treatment, and firing is complicated, and a binder such as a phenol resin is required. It was difficult to obtain a high-purity silicon carbide composite material due to the impurities and the like.

As a method of impregnating a porous silicon carbide molded body with metallic silicon, a method of heating metallic silicon to a temperature equal to or higher than its melting point and allowing the molten silicon to permeate is generally used.

Furthermore, a method has been proposed in which silicon carbide is vapor-phase evaporated to form a dense silicon carbide film on the surface of a silicon carbide material to suppress the diffusion of impurities.

Conventionally, silicon carbide materials used for semiconductor manufacturing are manufactured by performing appropriate purification treatment after molding and firing. However, since the purification treatment of the silicon carbide material is contaminated in a complicated manufacturing process and is performed after firing into a dense sintered body, impurity removal is limited to the surface. Therefore, when a silicon wafer material jig manufactured by the above-mentioned conventional method is used to heat-treat a silicon wafer, for example, impurities in the silicon carbide material are diffused and released, which may cause wafer contamination.

Therefore, a high-purity silicon carbide manufacturing process using a vapor-phase synthetic quartz porous material as a raw material has been proposed. However, since the shape of the quartz base material is limited, a complicated-shaped product such as a wafer boat or a process tube. There is a problem that it is difficult to manufacture such a large shaped product.

As a method of joining porous silicon carbide materials to manufacture a complex-shaped product or a large-sized product, a method has been proposed in which porous silicon carbide materials are superposed on each other at a bonding surface and bonded by metallic silicon. However, the joining by this method has a problem that the joining strength is small.

The present invention has been invented in view of the above problems, and is for producing a silicon carbide-based molded article having a high purity and having a complicated shape and a large-sized joint, which can be used in a semiconductor manufacturing process. It is intended to provide a way.

[0011]

In order to achieve the above-mentioned object, a method for manufacturing a silicon carbide-based molded article to be joined and formed according to the present invention comprises: stacking synthetic quartz glass porous bodies on a joining surface;
Carbon produced by thermal decomposition of a gas containing a hydrocarbon gas or a halogenated hydrocarbon gas is deposited in the porous body and the bonding surface at a carbon / silicon dioxide molar ratio of 3.5 or more, and then fired to obtain. The obtained porous silicon carbide molded body is filled with metallic silicon, and carbon produced by thermal decomposition of a gas containing a hydrocarbon gas or a halogenated hydrocarbon gas is added to the synthetic quartz glass porous body. In the porous silicon carbide molded body obtained by depositing at a molar ratio of / silicon dioxide of 3.5 or more, superposing the silicon dioxide-carbon porous molded body obtained by the deposition on the bonding surface, and then firing. The method is characterized in that it is filled with metallic silicon, and carbon generated by thermal decomposition of a gas containing a hydrocarbon gas or a halogenated hydrocarbon gas is added to the carbon / carbon Precipitated with 3.5 or more in a molar ratio of silicon oxide, then superimposing the firing to the obtained porous silicon carbide molded body joint surface is characterized by filling the following metal silicon.

[0012]

[Function] VAD (Vapor-phase Axial)
Deposition) vapor-phase synthetic quartz glass is porous, so that it is possible to deposit carbon even inside by heat treating in a carbon-containing gas atmosphere.
Therefore, a high-purity dense silicon carbide material can be obtained by treating the porous body on which carbon is deposited at a high temperature and further impregnating it with metallic silicon.

However, since it is difficult to manufacture and process the porous synthetic quartz base material into a large size and a complicated shape, it becomes necessary to join the synthetic quartz base materials processed into the respective shapes.

According to the method of the present invention, first, the vapor-phase synthetic quartz glass porous bodies that have been processed into a predetermined shape are brought together at the joint surface, and a hydrocarbon gas or a halogenated hydrocarbon gas (CH ₄ , C ₂ H _{6 is used).} , C ₃ H ₈ , C ₄ H ₁₀ , C ₂ H ₄ , C ₂ H ₂ , C ₂ H ₄ Cl ₄ , C
_{2 H 3 Cl 3, C 2} H 3 Cl, in an atmosphere comprising at least one among the C ₂ H ₂ Cl _2, etc.), the decomposition temperature or more gases, 1400
Heat treatment is performed at a temperature of not more than ℃ to deposit carbon inside the porous body. At this time, silicon carbide is generated according to the reaction formula represented by SiO ₂ + 3C → SiC + 2CO. Therefore, it is necessary to deposit carbon so that the amount of deposited carbon with respect to silicon dioxide becomes 3 in molar ratio. However, since silicon carbide is bonded after depositing excess carbon at the bonding interface, silicon dioxide is actually used. Carbon is deposited so that the amount of deposited carbon is 3.5 or more in terms of molar ratio. When the molar ratio of carbon to silicon dioxide is less than 3.5, the joining of the joining surfaces is mainly Si joining, and the high temperature joining strength is insufficient.

Next, the silicon dioxide-carbon porous compact is fired in the temperature range of 1600 to 2500 ° C. to obtain a porous silicon carbide compact of silicon carbide and excess carbon superposed on the joint surface. By filling this with molten metal silicon, excess carbon reacts with silicon at the bonding interface to form silicon carbide, and a strong bonded body is obtained.

The above-mentioned process can obtain an integrated joined body without a joining interface. However, when the joined body becomes relatively large, when the carbon is deposited from the hydrocarbon gas or the halogenated hydrocarbon gas, the surface layer and the central part are not formed. There may be a difference in carbon concentration between the parts, and carbon may not be uniformly deposited. Therefore, a method is also effective in which carbon is preliminarily deposited on the synthetic quartz glass porous body piece before bonding, and then a silicon dioxide-carbon porous molded body is superposed on the bonding surface, fired, and then filled with metallic silicon.

Further, even if carbon is deposited on the synthetic quartz glass porous body before bonding and fired, a porous silicon carbide molded body is superposed and then metal silicon is filled therein, a strong bonded body can be obtained.

Unlike the conventional joining using only metallic silicon, the joined body thus obtained has a completely identical structure to the silicon carbide base material, and the difference in thermal expansion coefficient at the base material-bonding interface. Since it does not exist, high bonding strength can be obtained even at room temperature and high temperature.

[0019]

EXAMPLES AND COMPARATIVE EXAMPLES Examples and comparative examples according to the present invention will be described below. Superposed synthetic quartz glass porous bodies having a bulk density of about 0.3 g / cm ³ and an average particle size of about 0.2 μm synthesized by the VAD method, and treated at a temperature of 1000 ° C. for different predetermined times in an atmosphere of 100% methane gas. Then, as shown in Table 1, porous bodies having different carbon deposition amounts were obtained.
This porous body was fired under vacuum at a temperature of 2000 ° C. for 3 hours to obtain a porous silicon carbide-carbon compact. This molded body was inserted into a graphite crucible, and massive metallic silicon having a purity of 10-N was placed around the crucible and heated at 1550 ° C., and the molten silicon was filled into the open pores of the molded body to form a silicon carbide material. Got the body

As another example, a silicon dioxide obtained by treating a synthetic quartz glass porous body obtained by the same method as the above example at a temperature of 1000 ° C. for a certain time in an atmosphere of 100% methane gas. -The carbon porous molded bodies were overlaid and fired under vacuum at a temperature of 2000 ° C for 3 hours to obtain a porous silicon carbide-carbon molded body. This molded body was filled with metallic silicon in the same manner as in the above-mentioned example to obtain a silicon carbide-based formed body.

As yet another example, a synthetic quartz glass porous body obtained by the same method as the above example was treated at a temperature of 1000 ° C. for a certain time in an atmosphere of 100% methane gas to give a porous silicon dioxide-carbon. A molded body was obtained. The silicon dioxide-carbon porous compact was fired under vacuum at a temperature of 2000 ° C. for 3 hours to obtain a porous silicon carbide-carbon compact. The compacts were stacked and filled with metallic silicon in the same manner as in the above-mentioned example to obtain a silicon carbide-based compact.

As a comparative example, a compact was obtained by joining a dense body which was a silicon carbide sintered body using metallic silicon.

Further, as another comparative example, a silicon carbide powder is molded and calcined to produce a silicon carbide porous body, and then carbon is applied to the bonding surface and metal silicon is filled therein to obtain a molded body. It was

[0024] The obtained silicon carbide forming body, 1300 ℃
The high temperature bonding strength in Table 1 is shown in Table 1 together with the comparative example, and the result of purity analysis is shown in Table 2.

[0025]

[Table 1]

[0026]

[Table 2]

In Tables 1 and 2, those marked with * are examples of the present invention, and the others are outside the present invention.

As is clear from Tables 1 and 2, the high-purity silicon carbide-based compacts in the examples showed higher strength than the conventional silicon bonded bodies. In addition, when a wafer boat was produced using this high-purity silicon carbide molding and used for wafer heat treatment, it was possible to operate without any problems in purity, strength, and durability. On the other hand, in the joining of silicon carbide dense bodies, the strength is significantly inferior to the base material. In addition, in the product manufactured by the method of coating the bonded surface of the porous silicon carbide body with carbon and then filling with metallic silicon, since the bonding layer and the base material are non-homogeneous, the strength is low, which is clear from Table 2. Thus, contamination of coating carbon and impurities from the coating process is observed.

As described above, according to the method for manufacturing a silicon carbide-based molded body to be bonded and formed according to the above-mentioned embodiment, it is possible to obtain an integral, large-sized or complex-shaped strong bonded body without a bonding interface. You can Further, even when the joined body becomes relatively large, when carbon is deposited from the hydrocarbon gas or the halogenated hydrocarbon gas, the difference in concentration of carbon deposited between the surface layer portion and the central portion is suppressed, and the carbon is uniformly deposited. It can be deposited and a strong joined body can be obtained. Therefore, it is possible to manufacture a high-purity silicon carbide molding useful for a jig for semiconductor production, for example, a heat-resistant jig such as a process tube or a wafer boat used for thermal diffusion treatment of a silicon wafer.

[0030]

As described above in detail, the method for manufacturing a silicon carbide-based molded article to be joined and formed according to the present invention is a method in which synthetic quartz glass porous bodies are superposed on a joining surface to form a hydrocarbon gas or a halogenated hydrocarbon gas. Carbon produced by thermal decomposition of a gas containing carbon is deposited in the porous body and the bonding surface at a carbon / silicon dioxide molar ratio of 3.5 or more, and then fired to obtain a porous silicon carbide molded body. Since it is filled with metallic silicon, it is possible to obtain an integral, large-sized or complex-shaped strong joined body having no joining interface.

Alternatively, carbon produced by thermal decomposition of a gas containing a hydrocarbon gas or a halogenated hydrocarbon gas is deposited on a synthetic quartz glass porous body at a carbon / silicon dioxide molar ratio of 3.5 or more, When the silicon dioxide-carbon porous compact obtained by precipitation is superposed on the joint surface and then the porous silicon carbide compact obtained by firing is filled with metallic silicon, the joint is relatively large. Even in the case where the carbon is deposited from the hydrocarbon gas or the halogenated hydrocarbon gas, the carbon concentration difference between the surface layer portion and the central portion can be suppressed, and the carbon can be uniformly deposited to form a strong bonded body. Obtainable.

Further, carbon produced by thermal decomposition of a gas containing a hydrocarbon gas or a halogenated hydrocarbon gas is deposited on a synthetic quartz glass porous body at a carbon / silicon dioxide molar ratio of 3.5 or more, and thereafter, When the porous silicon carbide compacts obtained by firing are superposed on the joint surface and then filled with metallic silicon, a hydrocarbon gas or a halogenated hydrocarbon gas can be used even if the joint body becomes relatively large. When carbon is deposited from the above, the carbon concentration difference between the surface layer portion and the central portion can be suppressed, carbon can be deposited uniformly, and a strong joined body can be obtained.

Therefore, a high-purity joint is formed which is useful for a jig for semiconductor manufacturing, for example, a complicated shaped product such as a wafer boat used for thermal diffusion treatment of silicon wafers, and a large shaped product such as a process tube. It enables the production of silicon carbide-based compacts, and is extremely useful in industry.

[0034]

Claims (3)

[Claims] 1. Synthetic quartz glass porous bodies are superposed on each other at a joint surface, and carbon produced by thermal decomposition of a gas containing a hydrocarbon gas or a halogenated hydrocarbon gas has a carbon / silicon dioxide molar ratio of 3.5 or more. 2. A method for producing a bonded silicon carbide-based molded product, comprising: depositing in the porous body and the bonding surface, and then firing the porous silicon carbide molded product, and filling the porous silicon carbide molded product with metallic silicon. 2. Carbon produced by thermal decomposition of a gas containing a hydrocarbon gas or a halogenated hydrocarbon gas in a synthetic quartz glass porous body has a molar ratio of carbon / silicon dioxide of 3.5.
It is characterized in that the above-described precipitation, the silicon dioxide-carbon porous molded body obtained by the deposition are superposed on the bonding surface, and the porous silicon carbide molded body obtained by firing is filled with metallic silicon. A method of manufacturing a silicon carbide-based molded body to be joined and formed. 3. Carbon produced by thermal decomposition of a gas containing a hydrocarbon gas or a halogenated hydrocarbon gas in a synthetic quartz glass porous body has a carbon / silicon dioxide molar ratio of 3.5.
A method for producing a bonded silicon carbide molded body, which comprises depositing the porous silicon carbide molded body obtained by the above and then stacking the porous silicon carbide molded bodies on each other at a bonding surface, and thereafter filling with metallic silicon.