JPS61253366A - Production of reaction sintering sic - Google Patents

Abstract

PURPOSE:To deposit reaction sintering SiC contg. a prescribed amount of Si by controlling the heating temp. of a substrate, the pressure during CVD and the ratio between Si and C in a gaseous starting material for depositing Si and SiC by CVD when the starting material is fed onto the substrate. CONSTITUTION:A gaseous starting material contg. CH2SiCl3 is fed onto a substrate, and the surface of the substrate is heated to >=about 650 deg.C to deposit reaction sintering SiC on the surface of the substrate. At this time, the Si content in the deposited SiC lowers in accordance with an increase in the heating temp., and the Si content in the thickness direction can be changed by changing the temp. of the substrate during CVD. The ratio between Si and SiC in the deposit can be adjusted to the desired value by regulating the pressure during CVD and the ratio between Si and C in the gaseous starting material.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a method for producing reactive sintered SiC, and in particular to a method for producing reactive sintered SiC.
It relates to a method for producing reactive sintered SiC that can contain SiC and SiC extremely uniformly in a desired ratio.

[Prior Art] In recent years, so-called new ceramics such as non-oxide ceramics such as silicon nitride, silicon carbide, and sialon, as well as aluminum oxide and zirconium oxide, have been rapidly focused on as high-temperature, high-strength materials, and many studies have been conducted. and are being developed.

Among these ceramics, silicon carbide (rS i
It is abbreviated as C4. ) is ■ a light material.

■ High mechanical strength and stability from room temperature to high temperature.

■ Excellent spalling resistance due to low thermal expansion and good thermal conductivity.

■ Extremely high corrosion resistance.

■ High hardness and excellent wear resistance.

■ It is conductive and can be used as an electric element.

It has these characteristics and is attracting attention as an extremely important industrial material. In particular, S produced by the reactive sintering method
iC is attracting attention because it can produce dense, high-strength sintered bodies even for objects with complex shapes. (In this specification, SiC containing Si is referred to as "reactive sintering type 5i").
Conventional, reaction sintering type S i Ct±, Si
A mixed powder of C and carbon (hereinafter abbreviated as "C") is molded, and silicon (hereinafter abbreviated as rsiJ) is injected into this molded body.
The molten metal is impregnated and reacted and sintered at a high temperature of 1,500 N and 1,600°C (this reaction formula is Si + C +
It is SiC. ) It is manufactured by filling the gaps between SiC grains with the generated SiC.

According to such a method, reaction sintered SiC can be obtained which is dense and has good thermal shock resistance, dimensional accuracy, etc., with almost no shrinkage during firing.

[Problems to be Solved by the Invention] The reactive sintered SiC obtained by the above conventional method contains unreacted Si in the sintered body. When this Si is uniformly dispersed in a sintered body, it has the advantage of increasing the toughness of SiC, but the reaction sintered Si obtained by the conventional method described above
Since the Si remaining in C is derived from the molten Si, it exists in the form of a lump or an elongated circle in the sintered body. Such residual Si portions may cause stress to be concentrated in the corresponding portions, or may form portions with low hardness and poor corrosion resistance.

[Means for Solving the Problems] The present invention solves the drawbacks of the above-mentioned conventional methods and provides a method for producing reactive sintered SiC in which a desired amount of Si is uniformly dispersed. CVD in which SiC is deposited by CVD reaction
When introducing the raw material gas onto the substrate and depositing SiC, a predetermined amount of S
The gist of the present invention is a method for producing reactive sintered SiC, which comprises a step of precipitating reactive sintered SiC containing i.

[Function] The present inventors used the well-known C to obtain the following SiC.
As a result of repeated research on the VD reaction, i.e. ■ thermal decomposition, for example CHaSiC3→SiC+3HC1 or ■ reduction of metal halides, for example 5iCu++CH4→SiC+4HcJL, we have found that the thermal decomposition reaction temperature, reaction pressure, or Si in the source gas: By controlling the C ratio, reactive sintered SiC with different Si contents can be produced depending on these factors.
We have completed the present invention by discovering that the following can be obtained, and that Si in the obtained reaction-sintered SiC is extremely uniformly dispersed.

That is, for example, in the reaction of producing SiC by thermal decomposition of CH3S i CJL3, the temperature is 650 to 1100°C.
By setting the temperature within this range, reactive sintered SiC containing Si can be obtained. Furthermore, by varying this thermal decomposition temperature in the range of 650 to 1100°C, it is possible to arbitrarily adjust the Si content in the resulting reactive sintered SiC.

Since the resulting reactive sintered SiC is a precipitate resulting from a gas phase reaction, Si is extremely uniformly and finely dispersed.

[Examples] Examples of the present invention will be described in detail below with reference to the drawings.

FIGS. 1(5L) to 1(C) are schematic cross-sectional views illustrating the manufacturing process of reactive sintering type SiC according to an embodiment of the present invention.

In this embodiment, as shown in FIG. 1(a), first, the substrate l is
Prepare a CVD film containing CH35iCJLa on the substrate l.
When supplying the raw material gas, at least the surface of the substrate 1 is heated to a temperature in the range of 650° C. or higher. ~ The heating method is not particularly limited, but may be an infrared heating furnace in which an infrared source is placed at two focal points in a cylindrical body with an elliptical cross section and a substrate is set between the front focal points, or an infrared heating furnace in which the substrate l has a simple shape or is conductive. In this case, a high-frequency induction heating furnace or the like with a simple device configuration is advantageous. In addition, an external heating method in which the reaction container is heated from outside can also be adopted.

A CVD raw material gas is supplied to the surface of the substrate l heated in this way, and a CVD reaction is caused, as shown in FIG. 1(b).
Reactive sintered z5tc (code 2) is deposited on the surface. The Si content in the reaction-sintered SiC that precipitates varies depending on the heating temperature; a high temperature results in a low Si content, while a low temperature results in a high Si content.For example, heating temperature 1020"
In c, reactive sintered SiC containing about 10 to 12% Si is obtained by thermal decomposition of 1 g of CHa S i C. The Si content varies slightly depending on the CVD raw material gas composition, and is expressed as CH3S i CJ13 /H2(++ jJ
When a hydrocarbon gas of CxHy (x and Y are integers) is mixed into 7 gas), reactive sintered SiC with a low 81 content can be obtained at the same temperature.

The deposition rate of reactive sintered SiC can be easily adjusted by adjusting the supply amount or heating time of CVD raw material gas.

After the reactive sintered SiC is deposited to a desired thickness, it is subjected to surface treatment such as polishing if necessary, and then used.

In addition, the board! The upper reactive sintered SfC layer 2 can be separated from the substrate 1, as shown in FIG. 1(C), depending on its intended use. In this case, one reaction sintering type S t C2 can be obtained by using a substrate l made of a material that has a coefficient of thermal expansion different from that of reaction sintering type SiC and does not substantially react with reaction sintering type SiC. can be peeled off more easily than the substrate l. Peeling can be done by applying a light mechanical shock to the interface between the reactive sintered SiC layer 2 and the substrate l, or by heating or cooling the vicinity of the interface and peeling by utilizing the difference in thermal expansion coefficient. method is adopted.

Alternatively, by using a material that can be removed by combustion or dissolution as the substrate 1 and removing the substrate 1, only the reactive sintered SiC 2 can be obtained. Examples of substances that can be removed by combustion include carbon. Further, as a material that can be dissolved and removed, for example, Ni and the like can be mentioned as a material that dissolves in acid.

In the method of the present invention, it is also possible to change the temperature of the substrate during the process to precipitate reactive sintered SiC having a different Si content in the thickness direction.

That is, in FIG. 2, the substrate l is heated to around 650° C. at the beginning of CVD raw material gas supply to precipitate reactive sintered SfC with a high Si content, and the heating temperature is gradually increased to increase the Si content in the direction of the arrow A. It is possible to deposit a small amount of reactive sintered SiC layer 2 and finally to deposit pure SiC. In this method, when forming the Si0 layer 2 on a metal substrate, the interface between the substrate 1 and the SfC calendar 2 should have a high Si content to improve the compatibility between the Si0 layer 2 and the substrate 1. It is advantageous for

According to the method of the present invention, a reaction-sintered SiC tubular member can also be manufactured.

In this case, the inner surface of the tube is made of only SiC,
If the outer surface side is configured to contain Si, a tubular member having an inner surface with high corrosion resistance and excellent overall strength and toughness can be obtained. Such a tubular member is extremely suitable as a reaction tube for vapor deposition processing of semiconductor silicon wafers.

An example of manufacturing a tubular member will be described next. The cylinder 3 of the carbon part as shown in FIG. 3(a) is used as a base, and the cylinder 3 is made of
Heat to ~800°C and add CH35iC/H2 gas (H
2 is a carrier gas) is supplied into the cylinder 3 to precipitate a layer 4 of reactive sintered SiC containing a relatively large amount of Si.Next, the heating temperature is gradually raised to about 1100'O to form pure Si.
A layer 5 of C is deposited. (Figure 3(b)).

Next, the cylinder 3 is burned and removed to obtain a tubular member 6 whose outer circumferential side is made of 5iC-3f and whose inner circumferential side is made of pure SiC, as shown in FIG. 3(C).

Note that in this production example, an example was shown in which CVD raw material gas was supplied to the inside of a cylindrical substrate to precipitate reactive sintered SiC, but CVD raw material gas was supplied to the outer periphery of the cylindrical substrate,
A good reaction tube can be obtained in the same manner by depositing reactive sintered SiC on the outer periphery. In this case, by setting the substrate heating temperature at around 1100°C at the beginning of CVD raw material gas supply and gradually lowering the heating temperature, the outer circumferential side is 5iC-5i and the inner circumferential side is pure S.
A tubular member made of iC can be manufactured.

In the above embodiment, CHaS is used as the CVD raw material gas.
fC statement 3 was used to adjust the temperature as a control factor for the SfC2C production rate; however, the present invention
D raw material gas may be employed and other control factors may be adjusted.

Other CVD raw material gases include the following.

■ S i H4/ CH4 ■ S i H4/ C2H4 ■ S i H4/ C3Hδ ■ S i Cl 4 / CCjL 4 ■ S f
Cfl, 4/C3Ha■ (CH3) 2 S
i CJ12 Other controlling factors include the following.

(a) Pressure during reaction (b) Si:C content ratio in raw material gas Among these three factors (a), (b) and the above temperature, any one of 1 or 2 or more depending on the characteristics of the raw material By adjusting the factors, it is possible to set the Si:SiC ratio in the precipitate to a desired ratio.

A specific example will be explained below.

Example", by the method of the present invention explained in FIG.
The formation rate (IL
/min), Knoop hardness of S i C film kg/
When we investigated the effect of temperature on the SiC content (mm") and SiC content, we obtained the result of the fourth factor. From the 1s4 diagram, 650
It is recognized that in the range of ~1100°C, the higher the temperature, the lower the Si content and the higher the Knoop hardness.

Moreover, at temperatures lower than 650°C, almost only Si precipitates, and at temperatures lower than 1100°C, substantially S
It is also observed that only iC is precipitated.

Note that the SiC content was measured by X-ray diffraction method.

CH4 was mixed with CHs Si C13 (the mixing ratio was 2.5%, 7.5%, and 12.5%), and SiC was precipitated in the same manner as in Example 1.

When the SiC content was identified and the hardness was measured, only sl' precipitated at temperatures below 650°C, as in Example 1.
At 0 to 1100°C, si and sic coexist, and 1100°C
If the temperature exceeds 650°C, only SiC will precipitate.
It was observed that the amount of SiC increased as the temperature increased between N1100''C.

[Effects] As detailed above, the method for producing reactive sintered SiC of the present invention adjusts the temperature, pressure, or Si:C ratio in the raw material gas when subjecting the CVD raw material gas to a CVD reaction. .

(2) Because of the gas phase reaction, reactive sintered SiC in which Sf is uniformly and finely dispersed can be produced.

(2) Therefore, the resulting reactive sintered SiC has extremely high strength, high toughness, and excellent corrosion resistance.

(2) The Si content in the resulting reactive sintered SiC can be easily adjusted to a desired content.

(2) Since it is a gas phase reaction, the Si content can be adjusted continuously, and it is possible to obtain reactive sintered SiC in which the Si content changes even within the same member.

■ By selecting the conditions, SiC can be produced at a temperature considerably lower than the sintering temperature of the conventional reaction sintering method (approximately 1500℃).
can be manufactured.

■ Since it uses the CVD method, it is possible to manufacture highly pure and dense products, and it is also possible to manufacture products with complex shapes.

■ By selecting the conditions, the production rate of one-reaction sintered SiC can be increased despite the low temperature.6For example, the production rate of SiC by normal CVD is about 4.5 times faster. obtain.

It has the following advantages and is extremely advantageous industrially.

The method of the invention can be used, for example, to manufacture reaction tubes, especially for processing semiconductor wafers.

[Brief explanation of drawings]

Figures 1 (a) to (C), Figures 2 and 3 (a) to (C)
) is a schematic cross-sectional view illustrating an example of the manufacturing process of reactive sintered SiC according to the present invention, and FIG. 4 is a graph showing measurement results in Examples. 1...Substrate, 2...Reactive sintered SiC layer. Agent Patent Attorney Shigeno Steel Department Figure 1 (a) 1lt (b) (C) Figure 3 (a)

Claims (1)

[Claims] (1) Precipitating Si and SiC by CVD reaction When introducing the CVD raw material gas onto the substrate and depositing SiC, one or more factors among the heating temperature, pressure, and Si:C content ratio of the raw material gas are selected. 1. A method for producing reactive sintered SiC, comprising the step of precipitating reactive sintered SiC containing a predetermined amount of Si.