JPH01290521A - Jig for heat treatment - Google Patents

Abstract

PURPOSE:To obtain a jig for heat treatment preventing the contamination of a wafer by the diffusion of impurities and capable of maintaining its strength even after repeated thermal shock tests by forming an SiC film having a specified thickness, a specified max. grain size and specified peaks of diffracted rays in X-ray diffraction on the surface of a base material. CONSTITUTION:An SiC film having 20-200mum thickness and 10-50mum max. grain size is formed on the surface of a base material by CVD or other method. In the X-ray diffraction of the film, the peak of diffracted rays at (220) face is 0.1-10 times as high as that at (111) face. The resulting jig for heat treatment has the above-mentioned characteristics, the corrosion resistance of the SiC film is not deteriorated and the jig is suitable for use as the material of a crucible, a susceptor, etc.

Description

[Detailed description of the invention] (Industrial application field) The present invention relates to a crucible used for manufacturing semiconductors.

Related to heat treatment jigs such as susceptors.

(Prior art) In order to avoid contaminating the above-mentioned heat treatment jig and semiconductors such as silicon, a method has been adopted in which the surface of a heat-resistant base material such as graphite is coated with high-purity silicon carbide. .

To form a high purity silicon carbide film on the surface of a substrate + C
HsSiCb+ (CHs)S+CI! A chemical vapor deposition (CVD) method in which chlorosilanes such as 5iC1a are decomposed at high temperatures, or mixtures of silicon chlorides such as 5iC1a and hydrocarbons such as methane are decomposed at high temperatures.

Japanese Patent Publication No. 54-90216 9% Publication No. 62-2974
As shown in Japanese Patent No. 67, etc., a method is known in which a solid raw material combining silica, carbon, etc. is reacted at high temperature.

(Problem to be solved by the invention) However, heat treatment jigs coated with silicon carbide (SiC) using the CVD method are prone to cracks and pinholes due to repeated use, and when solid raw materials are used, high purity It is said that it is difficult to obtain a SiC film, and in either case, the result is that the semiconductor wafer is contaminated.

SUMMARY OF THE INVENTION An object of the present invention is to provide a heat treatment jig for semiconductor manufacturing which improves the drawbacks of the prior art described above.

(Means for Solving the Problems) The present invention provides a heat treatment jig in which a SiC film is formed on the surface of a base material, the thickness of the SiC film is 20 to 200 μm, and the maximum size of crystal grains of the film is 10 to 50 μm. and a heat treatment jig in which the diffraction line peak value of the (220) plane in X-ray diffraction of a film is 0.1 to 10 times that of the (111) plane.

The reason why the SiC film thickness is set to 20 to 200 μm in the present invention is that if the thickness is less than 20 μm, when graphite is used as the base material, impurities in the graphite material will easily pass through the SiC film, reducing corrosion resistance and contaminating the wafer. death.

If the thickness exceeds 200 μm, the stress accumulated inside the SiC crystal increases the risk of breaking the SiC film.

In addition, the size of the crystal grains of the film was set to 10 to 50 μm because
If the thickness is less than 10 μm, impurities in the graphite base material will be diffused and Si
This is because it becomes easier to permeate the C film, and if the thickness exceeds 50 μm, the above-mentioned diffusion of impurities can be prevented, but the mechanical strength decreases. For example, crystal grains with a grain size of less than 10 μm have a bending strength of 600 MPa or more, whereas crystal grains with a grain size of 50 μm or more have a bending strength of 600 MPa or more.
If the bending strength exceeds 300-330MPa
decreases to

Furthermore, in the X-ray diffraction of the SiC film, the diffraction line peak values (I) of the (111) plane and (220) plane measured by Ka of Cu
The ratio I (220)/I (111) is 0.1 to 10. If it is less than 0.1, the SiC film will easily peel off;
This is because if it exceeds 0, cracks are likely to occur in the cross-sectional direction of the SiC film.

(Example) Next, the present invention will be explained in detail.

Example 1 An artificial graphite base material was placed in a CVD furnace, and the inside of the furnace was heated to 5 Tor.
While reducing the pressure to r, the substrate was heated to 1500°C, and CH
7 g of sSiC was introduced into a CVD furnace together with hydrogen gas as a carrier, and a 100 μm thick SiC film was coated on the surface of the base material. The maximum size of crystal grains on the film surface was 25 μm. FIG. 1 is an X-ray diffraction pattern of the SiC film. Cu,
The ratio of diffraction line peak values measured at I (220)/I (
111) is approximately 0.4 in FIG.

Comparative Example 1 The pressure inside the CVD furnace was 20 Torr, and the substrate temperature was 1
The surface of the substrate was coated with an 8iC film of about 100 μm under the same conditions as in Example 1 except that the temperature was 450° C.

The maximum dimension of M1 grains on the surface of the SiC film was 8 μm.

Comparative Example 2 Pressure in CVD furnace 3 Torr + substrate temperature 1550°C
Then, CH4 and 8iC14 were subjected to KCVD together with hydrogen gas.
It was introduced into a furnace, and a 100 μm SiC film was formed on the surface of the base material. The maximum size of crystal grains on the SiC film surface is approximately 100 μm
Met.

Next, the SiC films obtained in Examples and Comparative Examples were
(Tlrm) and heated at 500℃ for 10 minutes.
A thermal shock test was carried out by placing the specimen in water at a temperature of 0.degree. C., and the bending strength was measured each time to determine the relationship between the number of thermal shocks and the bending strength, which is shown in FIG. The number of samples each time was 10, and the bending strength values showed the average values.

As is clear from FIG. 1, the strength of the 8iC film of Comparative Example 1 rapidly decreased after five thermal shocks. This is thought to be due to the formation of a silica layer on the membrane surface due to the diffusion of impurities in the graphite base material. Comparative example 2 originally had a low strength of 10
The limit is the number of thermal shocks. On the other hand, in the case of the example, the bending strength hardly decreased even after 20 thermal shocks. Furthermore, no formation of a silica layer due to impurity diffusion was observed on the film surface.

(Effects of the Invention) According to the present invention, impurities do not diffuse and contaminate the wafer, the corrosion resistance of the SiC film does not deteriorate, and its strength can be maintained even after repeated thermal shock tests, so that it can be used in crucibles, susceptors, etc. A material suitable for a heat treatment jig can be provided.

[Brief Description of the Drawings] Figure 1 is an X-ray diffraction pattern of a SiC film coated on a heat treatment jig according to an embodiment of the present invention, and Figure 2 is a graph showing the relationship between the number of thermal shocks and bending strength. .

Claims (1)

[Claims] 1. In a heat treatment jig in which a silicon carbide film is formed on the surface of a base material, the film thickness of the silicon carbide film is 20 to 200 μm, the maximum dimension of the crystal grains of the film is 10 to 50 μm, and the X-ray diffraction of the film is A heat treatment jig in which the diffraction line peak value of the (220) plane is 0.1 to 10 times that of the (111) plane.