JPH06191971A - Complex ceramic member - Google Patents

Abstract

PURPOSE:To form a film of good quality without causing cracks and enable the formation of a film excellent in corrosion and oxidation resistance by coating the surface of a sintered compact consisting essentially of silicon carbide and silicon nitride with a complex film of the silicon carbide with silicon nitride. CONSTITUTION:This complex ceramic member has a complex film composed of silicon carbide and silicon nitride formed on a substrate composed of a complex sintered compact containing silicon carbide and silicon nitride at (1:9) to (9:1) ratio. The difference between the ratio represented by [silicon carbide/(silicon nitride + silicon carbide)] and the ratio of the complex film is within 0.3 expressed in terms of an absolute value. Thereby, a film of good quality without causing cracks in forming the film or polishing can be formed and the high-purity film can be formed while maintaining excellent mechanical characteristics of the substrate.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a composite ceramic member mainly composed of silicon carbide and silicon nitride, which is excellent in corrosion resistance and oxidation resistance.

[0002]

2. Description of the Related Art Sintered bodies composed mainly of silicon carbide and silicon nitride have attracted attention as engineering ceramics because of their excellent mechanical strength, hardness, heat resistance, etc., and have been applied as various structural materials or heat engine materials. There is.

The silicon nitride sintered body is excellent in strength, toughness and heat resistance, but has the property of lowering the strength at high temperature. The silicon carbide sintered body is excellent in high temperature strength and chemical resistance. However, there is a problem of poor toughness. Therefore, recently, a sintered body has been proposed in which these defects are compensated by compounding silicon carbide and silicon nitride.

On the other hand, ceramics may be coated with substances having different properties to improve their oxidation resistance and sliding properties for the purpose of modifying their surface, thereby expanding the field of application. Things are also being done.

In particular, silicon carbide and silicon nitride are also attracting attention as coating materials. For example, a CVD method or the like produces a high-purity film, which improves heat resistance and oxidation resistance. It is expected to be applied to jigs for semiconductor manufacturing.

[0006]

However, CV is formed on the surface of the substrate made of a composite sintered body of silicon carbide and silicon nitride.
When silicon carbide or silicon nitride is coated by the D method or the like, for example, according to the thermal CVD method, there is a difference in thermal expansion between the composite sintered body and silicon carbide or silicon nitride. Cooling process from generation temperature,
There was a problem that cracks were generated in the film during processing.

A plasma CVD method or PVD is used as a film forming method.
According to the method, synthesis can be performed at a lower temperature than the thermal CVD method, but internal stress due to the difference in thermal expansion between the substrate and the film is generated in the film, and if it becomes large, the film is also destroyed. .

For example, in the case where a composite material of silicon carbide and silicon nitride is coated with silicon carbide alone or silicon nitride alone, when the film thickness is about 10 μm or more, cracks are generated in the film due to thermal stress. Met.

[0009]

As a result of repeated studies on the above problems, the present inventor found that a film formed on the surface of a composite sintered body containing silicon nitride and silicon carbide as a main component was formed on a substrate. It was discovered that by forming a composite of silicon carbide and silicon nitride similar to the components, an excellent composite material can be obtained that has excellent adhesion to the substrate and does not cause cracks in the film.

That is, the present invention relates to a composite ceramic member characterized in that a composite film composed of silicon carbide and silicon nitride is formed on a substrate composed of a composite sintered body containing silicon carbide and silicon nitride as main components. Particularly, the difference between the ratio of silicon carbide / (silicon nitride + silicon carbide) in the substrate and the ratio of the composite film is within 0.3 in absolute value. is there.

The present invention will be described in detail below. The substrate in the composite ceramic body of the present invention is made of a sintered body containing silicon carbide and silicon nitride as main components, and specifically, the weight ratio of silicon carbide and silicon nitride is 1: 9 to 9: 1. Of Y ₂ O ₃ and Er ₂ O ₃ ,
Periodic Table 3a group metal oxides such as Yb ₂ O ₃ and Al ₂ O
₃ , adding a sintering aid such as MgO in a proportion of 0.5 to 20% by weight, and improving the characteristics of oxides, nitrides, carbides, carbon, etc. of transition metals of groups 4a, 5a and 6a of the periodic table. For the purpose, it may be added in a proportion of 0.1 to 30% by weight. This composite sintered body has a relative density of 95%.
The above is preferable from the viewpoint of stability of characteristics of the coating film and the composite ceramic body as a whole.

On the other hand, the composite film formed on the surface of the above-mentioned composite sintered body is composed of silicon carbide and silicon nitride as components similarly to the composite sintered body as the base, and the silicon carbide in the film is Silicon nitride weight ratio is 1: 9 to 9: 1
It is contained in the following ratio.

However, according to the present invention, the ratio of silicon carbide / (silicon nitride + silicon carbide) of silicon carbide of the composite sintered body which is the substrate and the composite film formed on the surface thereof to silicon nitride is set. The absolute value of the difference between the composite sintered body substrate and the composite film is preferably 0.3 or less. The difference in this ratio is 0.
This is because if it exceeds 3, the difference in thermal expansion between the substrate and the film becomes large, stress is generated in the film, and cracks occur in the film. The difference in the ratio between the substrate and the composite film is particularly preferably 0.2 or less.

The composite film formed on the surface of the substrate preferably has a thickness of 10 μm or more, and particularly, the above-mentioned silicon carbide / composite film of the composite sintered body and the composite film, which is the substrate, is formed.
If the ratio relationship of (silicon nitride + silicon carbide) is satisfied, 1
It has been confirmed that even if it is formed to a thickness of about 00 μm, there is no crack and no problem.

The composite film made of silicon carbide and silicon nitride can be formed, for example, by the CVD method. For example, a substrate made of a composite sintered body made of silicon carbide and silicon nitride is installed in a CVD furnace, and hydrogen gas is used as a diluent gas in the CVD furnace, and a silicon carbide forming gas made of a silicon-containing gas and a carbon-containing gas, At the same time as the silicon nitride forming gas consisting of the silicon-containing gas and the nitrogen-containing gas is introduced, the substrate 12
By heating to a temperature of 00 to 1600 ° C., a composite film of silicon carbide and silicon nitride can be formed on the surface of the substrate by decomposition of the reaction gas and deposition on the substrate. The composition ratio of the composite film can be controlled to an arbitrary composition by controlling the ratio of the gas introduced into the CVD furnace.

Examples of the silicon-containing gas include chlorides and hydrides of silicon, which may contain nitrogen. Further, hydrocarbon, carbon tetrachloride, etc. may be used as the carbon-containing gas, and nitrogen, ammonia, etc. may be used as the nitrogen-containing gas. Alternatively, Si (Me) ₄ containing silicon and carbon, methylchlorosilane, or the like, silazane containing silicon and nitrogen, or the like may be used.

[0017]

According to the present invention, by forming a composite film made of silicon carbide and silicon nitride having the same composition on a base made of a composite material of silicon carbide and silicon nitride, the thermal expansion of the base and the film can be achieved. Since it is possible to reduce the generation of stress due to the difference, it is possible to suppress the generation of cracks even if the film thickness is increased.

Thus, while utilizing the characteristics of the silicon carbide-silicon nitride composite sintered body, it is possible to form a high-purity composite film having substantially no grain boundaries on its surface with a sufficiently large thickness. For example, it can be applied to a jig for semiconductor manufacturing.

[0019]

The present invention will be described below with reference to the following examples. Example 1 A composite sintered body containing Y ₂ O ₃ at a ratio of 10% by weight and having silicon carbide / (silicon nitride + silicon carbide) = 0.65 was prepared,
This was installed in the CVD furnace. CH ₃ SiC there
_{l 3, SiCl 4, H 2} , and introducing a mixed gas of NH ₃ in CVD furnace, the substrate temperature 1500 ° C., subjected to film formation under the pressure 60 Torr, silicon carbide / (silicon nitride + SiC) is 0. A silicon nitride-silicon carbide composite film of No. 7 was deposited at 470 μm (Sample No. 1). For comparison, a silicon carbide simple substance film and a silicon nitride simple substance film were formed in the thicknesses shown in Table 1 (Sample No. 2).
Through 5).

When a total of 5 kinds of composites were subjected to grinding and polishing treatment with diamond abrasive grains for 30 minutes, as shown in Table 1, in Sample No. 1 having a silicon carbide-silicon nitride composite film formed thereon, polishing was carried out. After that, no cracks occurred at all. On the other hand, the silicon carbide simple substance film (Sample No. 2) and the silicon nitride simple substance (Sample No. 4) had no cracks immediately after the film formation, but cracks were observed during polishing. Further, in each of the thickened single films (Sample Nos. 3 and 4), cracks were generated immediately after the film formation.

The amounts of silicon carbide and silicon nitride in the films in the table were quantified by carbon analysis and nitrogen analysis. Further, the film thickness was judged from the SEM photograph. The peeling was judged after processing by grinding and mirror polishing.

Example 2 A composite sintered body containing Y ₂ O _{3 in an amount} of 8% by weight and having silicon carbide / (silicon nitride + silicon carbide) = 0.5 was prepared and CV was obtained.
It is installed in the D furnace, a mixed gas of SiH ₄ , H ₂ , NH ₃ , and C ₂ H ₂ is introduced into the CVD furnace, and the temperature is 1300 ° C. and the pressure is 5
Coating under 0 Torr, silicon carbide /
210μ composite film with (silicon nitride + silicon carbide) 0.55
m (sample No. 6). For comparison, silicon carbide alone was coated to a film thickness of 51 μm (Sample N
o.7). Similarly, a coating of 46 μm of a simple substance of silicon nitride was performed (Sample No. 8).

For each composite, the state of the film immediately after film formation and after polishing treatment was observed in the same manner as in Example 1. As a result, as shown in Table 1, the silicon carbide-silicon nitride composite film of Sample No. 6 had no cracks at all even after polishing. In comparison, cracks were found in the silicon carbide single film of sample No. 7 and the silicon nitride single film of sample No. 8.

Example 3 A sintered base body containing silicon carbide and silicon nitride as main components and having a weight ratio of silicon carbide / (silicon nitride + silicon carbide) = 0.33 was placed in a reactor, and CH was placed therein. ₃ SiCl ₃ , H ₂ , Si
A mixed gas of Cl ₄ and NH ₃ is introduced, and the temperature is set to 1400.
Coating at 60 ° C and a pressure of 60 Torr,
Several composites having different ratios of silicon carbide and silicon nitride were prepared (Samples No. 9 to 13).

As a result, a sample No. 1 made of a silicon nitride film was obtained.
In No. 3, cracking was observed, and in the sample No. 10 in which the difference between the substrate and the film in the ratio of silicon carbide / (silicon nitride + silicon carbide) was larger than 0.3, in the case of the silicon carbide single film or the silicon nitride single film, There was no crack, but a slight crack was observed.

[0026]

[Table 1]

EXAMPLE 4 Silicon carbide, which was obtained by reacting and sintering silicon carbide under a high pressure of 1000 atm of nitrogen, was composed of silicon nitride and carbon.
A sintered body having a weight ratio of (silicon nitride + silicon carbide) = 0.25 was placed in a reaction furnace, and SiCl ₄ , H ₂ , N
A composite film of silicon carbide / (silicon nitride + silicon carbide) = 0.20 was synthesized with a gas of H ₃ and C ₂ H ₂ to a thickness of 140 μm. The obtained composite film had no cracks immediately after film formation and after polishing.

[0028]

As described above, according to the present invention, by coating the surface of the sintered body containing silicon carbide and silicon nitride as the main component with the composite film of silicon carbide and silicon nitride, no cracks are generated. Film is formed. As a result, it became possible to form a coating having excellent corrosion resistance and oxidation resistance and high purity while maintaining the excellent mechanical properties of the composite material.

As a result, the use of the silicon carbide sintered body as a jig for semiconductor parts, high-temperature mechanical materials, sliding members, etc. can be expanded.

Claims (2)

[Claims] 1. A composite ceramic member having a composite film made of silicon carbide and silicon nitride formed on a base body made of a composite sintered body containing silicon carbide and silicon nitride as main components. 2. Silicon carbide / (silicon nitride +) in said substrate
The composite ceramic member according to claim 1, wherein a difference between the ratio represented by (silicon carbide) and the ratio of the composite film is within 0.3 in absolute value.