JP2002037684A - Regenerating method of silicon carbide-coated graphite element and silicon carbide-coated graphite element by the method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a regenerating method of a SiC coated-graphite element, and a SiC coated-graphite element which is regenerated by the method. The SiC-coated graphite element which has become its life end consisting of a SiC- coated graphite element, and used as an element for pulling up monocrystal, and as a suscepter for the epitaxial growth of a silicon wafer in a semiconductor manufacturing process which can homogeneously remove surface-coated SiC, can use a small type exhaust gas treating device and can reduce the semiconductor manufacturing cost. SOLUTION: The SiC-coated graphite element is reused after coating SiC with CVD method on the base material which is evaporated the surface coated SiC at a temperature not less than 1700 deg.C, under pressure not higher than 1.33 kPa, in an innert gas atmosphere or under pressure not higher than 1.33 kPa in an innert gas atmosphere.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for regenerating a silicon carbide-coated graphite member that has reached the end of its life and to a silicon carbide-coated graphite member regenerated by the method.

[0002]

2. Description of the Related Art Conventionally, graphite members coated with silicon carbide have been
It is widely used in parts for which heat resistance, corrosion resistance and thermal shock resistance are required, such as members for semiconductor manufacturing equipment and members for glass product manufacturing equipment. For example, silicon carbide (hereinafter, referred to as CVD method) on a surface of a high-purity isotropic graphite material for a member for pulling a single crystal in a semiconductor manufacturing process, a susceptor for epitaxial growth of a Si wafer, or the like. , SiC) is used. The use of these SiC-coated graphite members is discontinued when the surface of the SiC is peeled off or imperfections such as pinholes, which are thought to be caused by impurities mixed in for some reason during the semiconductor manufacturing process. And was disposed of as a life end.

[0003]

With the rapid increase in demand for semiconductor-related products in recent years, semiconductor prices have fallen, and it has become essential for semiconductor manufacturers to reduce semiconductor manufacturing costs. There is a demand for recycling of members made of graphite materials coated with SiC.

For example, Japanese Patent Application Laid-Open No. 9-241086 discloses
Japanese Patent Application Laid-Open No. H11-163873 discloses that a silicon carbide-coated graphite member is contacted with a gas containing halogen and heated to convert the silicon carbide coating into a carbon layer. A method of regenerating a silicon carbide-coated graphite member by forming a film of the above-described method to obtain a silicon carbide-coated graphite member is disclosed.

However, in this method, since the silicon carbide film coated on the surface is heated by being brought into contact with an expensive halogen-containing gas, treatment of the halogen-containing gas used at that time and the halogen-containing gas are included. A large exhaust gas treatment device is required for treating Si gas that decomposes and sublimates depending on the gas, and the semiconductor manufacturing cost has not been significantly reduced. Further, since the treatment is performed using a gas containing halogen, there is a possibility that SiC may be unevenly removed by a selective reaction.

Accordingly, the present invention provides a member for pulling a single crystal in a semiconductor manufacturing process capable of uniformly removing SiC coated on the surface, using a small exhaust gas treatment device, and reducing semiconductor manufacturing costs. , A method of regenerating a SiC-coated graphite member made of a SiC-coated graphite material and used as a susceptor for epitaxial growth of a Si wafer and having a life end, and Si regenerated by the method.
An object is to provide a C-coated graphite member.

[0007]

In order to solve the above-mentioned problems, a method for regenerating a silicon carbide-coated graphite member in which a graphite base material is coated with silicon carbide according to the present invention comprises the steps of: The graphite substrate removed by heat treatment under a pressure of 1.33 kPa or less or under an inert gas atmosphere or under an inert gas atmosphere under a pressure of 1.33 kPa or less is subjected to SiC by CVD. Is coated. Further, after the heat treatment, a general purifying furnace used for purifying the graphite material may be used in a gas atmosphere containing halogen for 200 hours.
A heat treatment at 0 ° C. or higher can completely remove SiC on the surface, and can appropriately add a high-purity treatment for removing impurities near the surface layer. This is because it is possible to prevent the SiC from being separated due to impurities and the like when the SiC is coated again by the CVD method. In addition, the SiC-coated graphite member mentioned here is, specifically,
The members used for the single crystal pulling furnace, such as crucibles, upper and lower rings, or upper and lower cones,
It includes pancake susceptors and barrel susceptors used as susceptors for epitaxial growth, and all other graphite materials coated with SiC such as heaters, laser mirrors, refractories for melting metals, and oxidation-resistant members.

[0008] As described above, the present invention provides a method for removing SiC coated on the surface of a graphite material as a substrate at 1700 ° C or more, preferably 2000 ° C or more, more preferably 2500 ° C or more, for 10 hours or more, preferably 20 By performing heat treatment for more than an hour, SiC is sublimated and removed from the graphite material surface.

Generally, metallic silicon is attached to the surface of SiC of the susceptor for epitaxial growth used in the semiconductor manufacturing process.
When heat-treated at a temperature of at least 2000C, preferably at least 2500C, more preferably at least 2500C, for at least 10 hours, preferably at least 20 hours, it becomes possible to remove together with SiC. This metal silicon may be dissolved in a hydrofluoric / nitric acid solution or mechanically removed with a grinding wheel as a pretreatment.

Further, the heat treatment is performed under a pressure of 1.33 kPa or less, preferably under a pressure of 0.67 kPa or less and / or in an inert gas atmosphere, for example, an argon gas, a nitrogen gas, especially an argon gas atmosphere. . By performing the heat treatment under such a low pressure, sublimation of the SiC coated on the surface can be promoted, and the SiC can be uniformly removed. Further, by lowering the oxygen partial pressure of the atmosphere during the heat treatment, SiC can be removed without silicon dioxide or the like remaining on the surface of the graphite material after the heat treatment. At this time, some SiC may remain on the surface. As described above, when removing SiC, a gas containing halogen is not used, so that safety is excellent and a large-sized exhaust gas treatment facility is not particularly required.

[0011] By coating the surface with SiC after the above-mentioned heat treatment, it becomes possible to use it as a SiC-coated graphite member. It is preferred to treat with. As a result, SiC can be completely removed, and impurities on the surface can be removed.
Exfoliation of SiC and generation of pinholes immediately after iC coating can be suppressed. In addition, blasting may be performed with ceramic powder or the like before the treatment in a halogen gas atmosphere.

After removing the surface SiC, the surface of the graphite material is coated again with the SiC by the CVD method. As a raw material gas used in the CVD method, a mixed gas of SiCl ₄ and C ₃ H _8, a mixed gas of SiH ₄ and C ₃ H _{8 and} the like can be exemplified. Using hydrogen gas as a carrier gas for this source gas, 1000 to 1600 ° C., 0.001 to 0.1
By performing the CVD process under the condition of MPa and coating the surface of the graphite material with SiC, it can be reused as a SiC-coated graphite member. Here, the thickness of SiC is 3
The thickness is set to 0 to 200 μm, preferably 60 to 150 μm.

As described above, the SiC coated on the surface of the SiC-coated graphite member which has reached the end of its life can be removed, and the surface is coated with high-purity SiC again by the CVD method. It can be reused as a graphite member.

[0014]

EXAMPLE A susceptor which was used as a susceptor for epitaxial growth and had a life end due to a pinhole generated for some reason on its surface was heated at 2500 ° C.
Heat treatment was performed at 3.3 Pa for 72 hours. Next, a mixed gas of SiCl ₄ and C ₃ H ₈ was used as a source gas on the surface thereof, and hydrogen gas was used as a carrier gas.
CVD treatment is performed at 0 ° C. and 0.1 MPa to reduce SiC to 1
It was formed with a thickness of 20 μm. In this way, Si
After being coated with C, it was used as a susceptor for epitaxial growth. However, no abnormality was found in the crystals formed on the silicon wafer, and it was possible to reuse it as a susceptor for epitaxial growth.

[0015]

The present invention is configured as described above.
It is possible to remove the SiC coated on the surface of the SiC-coated graphite member which has reached the end of its life, and to coat the surface again with high-purity SiC by the CVD method.
It can be reused as a coated graphite member, which has the effect of reducing semiconductor manufacturing costs and industrial waste. In addition, since expensive gas containing halogen is not used at the time of removing SiC, safety is excellent and manufacturing cost can be reduced. Further, unlike the case where a gas containing halogen is used, SiC is not selectively removed but is uniformly removed.
When Si is recoated, a uniform film of SiC can be formed.

Claims (2)

[Claims] 1. A method for regenerating a silicon carbide-coated graphite member in which a graphite base material is coated with silicon carbide, wherein the silicon carbide coated on the surface is heated to 1700 ° C. or more under a pressure of 1.33 kPa or less. Under an active gas atmosphere, or 1.33
A method for regenerating a silicon carbide-coated graphite member, wherein the graphite substrate removed by sublimation by heat treatment under an inert gas atmosphere under a pressure of kPa or less is coated with silicon carbide by a CVD method. 2. A graphite member coated with silicon carbide which has been regenerated by the method of claim 1.