JP3779348B2 - High purity furnace for graphite members - Google Patents

Description

[0001]
[Industrial application fields]
The present invention relates to a graphite member high purification furnace for obtaining a high purity graphite member.
[0002]
[Prior art]
Graphite members are attracting attention as materials for highly industrially important members such as semiconductor devices and nuclear reactor devices because of their excellent heat resistance, chemical resistance, thermal conductivity, and mechanical strength at high temperatures. ing.
In recent years, it has further been found that it has many utility values in the fields of silicon single crystal pulling apparatus members, epitaxial growth susceptors, plasma CVD boards, etching electrodes, and the like. However, extremely high purity is required for the graphite members used in these applications.
[0003]
As a method for purifying a graphite member for obtaining a high-purity graphite member, for example, a graphite furnace member is disposed in a high-purification treatment furnace, and a packing powder such as coke is placed in a gap between the furnace wall and the graphite furnace member. A method of energizing the electrodes on both side walls while flowing halogen gas from one side of the furnace side wall, installing a tight box made of graphite furnace members in the processing vessel, and introducing the halogen gas while heating this For example, Japanese Laid-Open Patent Publication Nos. 63-248703 and 63-79759 disclose methods for performing forced exhaust.
[0004]
However, in these methods, it takes a long time, there is inconvenience in the work environment, the amount that can be processed at one time is limited, the processing of large items is impossible, there are problems in maintenance, There were many problems.
[0005]
Japanese Patent Application Laid-Open No. 6-298510 discloses a technique that enables a large-sized product to be processed by a method of heating the inside of a sealed container with a heater without providing a tight box in the high-purification processing furnace. However, the high purity of the treated graphite member is not different from the conventional method and still has a problem.
[0006]
[Problems to be solved by the invention]
In the conventional furnace for purifying graphite members, there is a certain limit to the purification of graphite members. Since the graphite constituting the furnace member of these high-purity treatment furnaces is porous, impurities removed from the product to be treated during the high-purification treatment are adsorbed by the furnace members in the furnace during cooling after the treatment. The In the next processing, the inside of the high-purity processing furnace becomes high temperature again, so that the adsorbed impurities are released to contaminate the furnace atmosphere.
[0007]
By repeatedly using such a high-purity treatment furnace, accumulation of adsorbed impurities occurs, and the degree of contamination of the atmosphere in the furnace is further increased, which makes it possible to complete the removal of impurities from the product to be treated. Will gradually decline. A certain limit of the above-mentioned high purity has existed for this purpose.
[0008]
Furthermore, in addition to the above problems, if the furnace material in the furnace is porous, the halogen gas introduced into the furnace passes through the porous furnace member, corrodes the processing vessel, or corrodes. Problems such as re-contamination of products to be treated with metal components, shortening of the life of processing containers, difficulty in maintenance, and the like have occurred.
[0009]
In view of the above, it is an object of the present invention to provide a high-purity treatment furnace for a graphite member that is highly purified and easy to maintain.
[0010]
[Means for Solving the Problems]
In order to achieve the above object, a graphite member high-purity processing furnace of the present invention comprises a processing vessel, a graphite furnace member that accommodates a processed product disposed in a central portion of the processing vessel, and the processed product. In a graphite member high-purification treatment furnace having a heater for heating, a halogen gas inlet, and a halogen gas exhaust port, the graphite furnace member is porous and has a dense pyrolytic carbon on its inner surface. A film is formed.
[0011]
The pyrolytic carbon film can be formed by various commonly used chemical vapor deposition (CVD) methods. For example, the surface of the graphite furnace member is heated to 800 to 2600 ° C., and hydrocarbon or halogenated hydrocarbon is brought into contact therewith in the presence of hydrogen gas, and the surface of the graphite furnace member having a large number of pores is made of pyrolytic carbon. A dense layer is formed.
[0012]
The above reaction can be carried out under normal pressure or reduced pressure, but in order to improve the uniformity and smoothness of pyrolytic carbon, it is preferably carried out under reduced pressure, particularly preferably 300 Torr or less.
[0013]
The thickness of the pyrolytic carbon coating is preferably 10 to 200 μm. If it is less than 10 μm, sufficient impermeability cannot be obtained, and if it exceeds 200 μm, there is a high possibility of causing cracks on the surface.
[0014]
[Action]
The dense coating of pyrolytic carbon has a strong gas impermeability. The surface of the graphite furnace member, which is a porous body, is obtained by forming a pyrolytic carbon film on the inner surface of the graphite furnace member disposed in the center of the graphite member purification furnace of the present invention. A strong gas impermeability is imparted.
[0015]
Thereby, impurities removed from the article to be processed are not adsorbed inside the graphite furnace member. Therefore, there is no contamination of the furnace atmosphere, and the purification of the product to be processed becomes more perfect. Further, the permeation of halogen gas from the graphite furnace member is eliminated. Accordingly, there is no concern about the corrosion of the processing container or the recontamination of the object to be processed due to the corroded metal component, and the service life of the processing container is not shortened.
[0016]
In the high-purification processing furnace of the present invention, when a heater is disposed on the outer periphery of the graphite furnace member, it is necessary to efficiently transfer the heat from the heater to the product to be processed inside the graphite furnace member. For that purpose, the graphite furnace member preferably has good heat conduction. In the present invention, only the inner surface of the graphite furnace member is covered with the pyrolytic carbon film, so that the above heat conduction is maintained in a good state, and the above-mentioned characteristic effect of the present invention is obtained. There is no loss.
[0017]
【Example】
Hereinafter, the present invention will be described in detail with reference to examples. FIG. 1 shows an example of a graphite member purification furnace of the present invention. The entire graphite member purification furnace is disposed inside the processing vessel 11. The article 14 to be processed is accommodated in the graphite furnace member 13. The inner surface 13a of the graphite furnace member 13 is formed with the pyrolytic carbon coating of the present invention. The heat from the heater 12 is transmitted to the workpiece 14 with good thermal conductivity. A halogen gas is supplied into the graphite furnace member 13 from a halogen gas introduction port 15, and this halogen gas is exhausted from a halogen gas exhaust port 16.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of a graphite member purification furnace of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 11 Processing container 12 Heater 13 Graphite furnace member 13a Inner surface 14 of graphite furnace member 14

Claims (2)

A processing vessel, a graphite furnace member that accommodates an object to be processed disposed in a central portion in the processing vessel, a heater for heating the object to be processed, a halogen gas inlet, and a halogen gas exhaust port In a graphite member high-purity treatment furnace, the graphite furnace member is porous, and a dense coating of pyrolytic carbon is formed on the inner surface of the graphite furnace member. .   The graphite member high-purity treatment furnace according to claim 1, wherein the pyrolytic carbon film has a thickness of 10 to 200 µm.

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