JPS5910954B2 - Method for manufacturing silicon carbide bodies for semiconductor manufacturing - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a silicon carbide body for semiconductor manufacturing, and more specifically to a method for manufacturing a silicon carbide body having a dense silicon carbide film on the surface used for semiconductor material mounting jigs, soaking tubes, etc. This relates to the manufacturing method.

Conventionally, this type of member has been made of recrystallized silicon carbide material (silicon carbide material) that has high thermal conductivity and excellent spalling resistance.
It has an apparent porosity of around %.

For this reason, when a soaking tube is formed from the silicon carbide material,
During operation, alkali substances that evaporate from the high-temperature furnace wall easily pass through the pores of this heat soaking tube and not only devitrify the quartz tube inside it, but also partially pass through the quartz tube and destroy semiconductors. There was a risk of contaminating the materials. In addition, when a semiconductor material mounting jig is formed from the silicon carbide material, HF-HNO
During cleaning with a mixed acid, there was a risk that moisture and impurities would enter the pores of the jig, making it unusable. In order to improve this drawback, a method for manufacturing a silicon carbide body for semiconductor production having a dense silicon carbide film has been proposed, in which silicon carbide is vapor-deposited on the surface of a silicon carbide material under vacuum. There is.

However, the silicon carbide bodies obtained by this method often have pinholes in the silicon carbide film on the surface, the film has poor adhesion and easily cracks due to mechanical impact, and is particularly difficult to use if it has complex structures with concave or bent parts. When a silicon carbide material with a shape of 25 is used, pinholes occur and adhesion deteriorates significantly, so as mentioned above, there is a risk that vaporized alkaline substances may pass through or moisture or impurities may be mixed in. For this reason, the present inventor conducted various studies on the causes of pinhole formation and deterioration of adhesion in the silicon carbide film formed on the surface of the silicon carbide material 30, and found that due to the large amount of impurities in the silicon carbide material, When silicon carbide is vapor-deposited on the surface of the silicon carbide material under vacuum, a large amount of low-boiling point substances are gasified, inhibiting the silicon carbide from riding on the material, resulting in the formation of pinholes and poor adhesion. It was found that a decrease in

Based on this investigation result, further intensive research revealed that a high-purity silicon carbide material with controlled impurity contents, particularly iron, copper, sodium, potassium, and lithium, was used, and silicon carbide was added to the material under vacuum. By vapor-phase deposition, it is possible to suppress the generation of gas from the silicon carbide material and form a uniform dense silicon carbide film that is gas impermeable even on the surface of the concave and bent parts of the silicon carbide material, making it possible to It has been found that a silicon carbide body for semiconductor manufacturing can be obtained which can prevent the permeation of vaporized alkaline substances during cleaning and the contamination of moisture and impurities during cleaning. In this case, the optimum purity of the silicon carbide material is to reduce the impurity content to less than 500% iron, less than 10% copper, sodium,
Potassium and lithium should each be below 5. The present invention will be explained in detail below. First, the impurity content is less than 500p1m of iron, less than 10% copper, sodium,
Potassium and lithium are each added to a silicon carbide material of 5PF or less in a vacuum, preferably under a vacuum of 10 torr or less, with silicon-based gasified substances such as silicon halides, silicon dioxide gas, and silicon hydride, and carbon-based hydrocarbons and carbon-based materials such as carbon dioxide. 1300~
It is heated to a temperature of 1900° C., and the silicon-based gasified material and the carbon-based gasified material are reacted to vapor-deposit silicon carbide on the surface of the silicon carbide material to produce a silicon carbide body for semiconductor manufacturing.

The silicon carbide material in the present invention has pores created by mixing silicon carbide powder with an organic binder, shaping it, first calcining to carbonize the organic binder, and then firing it in a filling powder such as silica powder. Although it is possible to use a recrystallized silicon carbide body having a porosity of about 20%, it is more preferable to deposit silicon carbide on this recrystallized silicon carbide body at normal pressure and use it as having a porosity of about 5%.

Further, the shape of this silicon carbide material is arbitrary, such as a tube, a plate, a tube with a slit, or a plate. Furthermore, the reason why the impurity content of this silicon carbide 5 material was limited to the range mentioned above is that if the content of each impurity exceeds the upper limit mentioned above, gas will be removed from the material when silicon carbide is vapor-deposited on the material. This is because pinholes are likely to occur and adhesion is reduced, making it impossible to obtain a silicon carbide body for semiconductor manufacturing having a gas-impermeable 4-dense silicon carbide film. Note that, for the purpose of increasing the adhesion of the silicon carbide film to the silicon carbide material, the surface of the silicon carbide material may be smoothed by polishing.

If necessary, silicon carbide may be vapor-deposited on the surface of the silicon carbide material under vacuum to form a silicon carbide film, and then silicon carbide may be further deposited on the silicon carbide film under normal pressure. Next, examples of the present invention will be described.

Example 1 Iron 400P, copper 5P, sodium 3P, potassium 2PP
1. A high purity silicon carbide material with an impurity content of 2P lithium (porosity 5%, dimensions 30W x 400L x 5t7n) was cut with a diamond cutter to a width of 0.8mm and a depth of 5m11.
After forming 80 grooves at intervals of 3 m and 71 L, the silicon carbide material was washed with HF-HNO3 mixed acid to remove dirt from processing, thoroughly washed with ion-exchanged water, and dried.

Next, a mixture of silicon suboxide gas obtained by directly evaporating silica and hydrocarbons in a molar ratio of 1:1 was supplied to the silicon carbide material under vacuum, and the mixture was heated at a temperature of 1800°C for 30 minutes.
A semiconductor manufacturing jig having a silicon carbide film on the surface was obtained by heating for 0 hours. In the obtained semiconductor manufacturing jig, a dense silicon carbide film of 0.1 mm was uniformly formed on the surface of the groove. Comparative example: Iron 3000P, copper 30PFL. Sodium 10PFL. Potassium 8PFL. A jig for semiconductor manufacturing was obtained in the same manner as in the previous example except that a silicon carbide material containing a large amount of impurities such as 8 lithium atoms was used.

In the obtained semiconductor manufacturing jig, not only was no silicon carbide film formed on the surface of the groove, but also pinholes were observed in the silicon carbide film formed on other smooth surfaces. After manufacturing a silicon semiconductor by placing a silicon wafer in the groove of the semiconductor manufacturing jig of Example 1 and Comparative Example, the surface of each jig was cleaned with HF-HNO3 mixed acid and dried. death,
Silicon semiconductors were manufactured again. As a result, the semiconductor obtained using the jig of the present invention was not contaminated, had no etch pits, and had an extremely long lifetime.
On the other hand, semiconductors obtained using conventional jigs are contaminated by impurities mixed in during cleaning of the jigs, generate many etch pits, and have short lifetimes. Example 2 Impurity content is iron 50PFL. Copper 2 pyn. Sodium 1P to potassium 1PFL. Lithium 1PF1 high purity tubular silicon carbide material (porosity 5%, dimensions 90φ x 500M
A soaking tube for semiconductor manufacturing having a silicon carbide film on the inner and outer surfaces was obtained in the same manner as in the previous example except that 1L) was used.

The obtained soaking tube had a uniform dense silicon carbide film of 0.1 mm formed thereon, and was gas impermeable.

As described in detail above, according to the present invention, a gas-impermeable, uniform, dense silicon carbide film is formed on the surface of a silicon carbide material having a desired shape, particularly a complex shape having concave portions and bent portions, and vaporization during operation is achieved. According to the present invention, it is possible to obtain a silicon carbide body for semiconductor manufacturing that can prevent permeation of alkaline substances and contamination of moisture and impurities during cleaning, and has a long service life.

Claims (1)

[Claims] 1 Impurity content: iron 500ppm or less, copper 10ppm
Hereinafter, a method for manufacturing a silicon carbide body for semiconductor manufacturing, which comprises vapor-depositing higher purity silicon carbide on the surface of a silicon carbide material containing 5 ppm or less of sodium, 5 ppm or less of potassium, and 5 ppm or less of lithium under vacuum.