JP2649679B2 - Susceptor for vapor phase growth and method for producing the same - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a susceptor for vapor phase growth used in an epitaxial process of growing a different layer on a thin wafer in a process of manufacturing a transistor and the like, and a method for manufacturing the same. .

[Conventional technology]

A conventional susceptor for vapor phase growth is a susceptor substrate formed by molding graphite powder according to a target shape, and a SiC film is formed on the susceptor substrate by a CVD method.

In order to fix the movement of the wafer subjected to the epitaxial process, a storage space corresponding to the outer shape of the wafer has been cut open on the surface and used as a susceptor for vapor phase growth.

[Problems to be solved by the invention]

According to the above-described conventional method, graphite and SiC components having completely different chemical compositions come into contact with each other, so that the adhesion between them is poor, and phenomena such as cracks and peeling occur during use.

Although there is no problem when performing the epitaxial process under mild temperature conditions, graphite and SiC
Since the thermal expansion coefficients of the coatings are slightly different, this also causes cracks, peeling, and the like, and there is a problem that the life of the susceptor is shortened.

[Means for solving the problem]

In order to overcome the above problems, the present invention uses SiC in graphite.
By using a susceptor substrate mixed with, a difference in the physical property values of graphite-SiC bilayers was reduced, and a susceptor for vapor phase growth with improved quality and a manufacturing method thereof were developed.

That is, graphite containing 0.5 to 15 wt% of SiC with respect to graphite and Si
By forming a SiC coating on the surface of a susceptor substrate made of C by using a CVD method with SiC distributed on the susceptor substrate surface as a nucleus, a difference in thermal expansion coefficient between the susceptor substrate and the SiC coating is offset, and the SiC coating and the susceptor are removed. Since the concentration gradient between the substrate and the substrate is reduced, a good and uniform susceptor is obtained.

In addition, instead of depositing SiC on the surface of a susceptor substrate made of only graphite according to the conventional method, SiC distributed on the surface of the susceptor substrate is used as a nucleus to form a SiC film by a CVD method. A strong chemical bond is formed between the SiCs, and the adhesion between the two is enhanced, and phenomena such as cracks and peeling are suppressed.

The susceptor is made of graphite powder, metal silicon, silicon nitride, a silicon oxide compound, or a silane compound (eg, polycarbosilane) that does not contain a group III or group V element.
Mixed with a silicon-containing compound such as, and molded, under a high-temperature inert atmosphere of 1300 ° C. or more or under a reduced pressure atmosphere not oxidized, preferably at 1 Torr or less, and react them with graphite at 0.5 to 15 wt. % Of SiC on the surface of a susceptor substrate composed of graphite and SiC.
It can be obtained by forming a SiC coating using SiC distributed on the surface of the susceptor substrate as a nucleus.

(Operation and Example)

Examples of the present invention will be described in detail below, the type of graphite powder used, particle size, purity, molding method, type of silicon-containing compound, particle size, compounding amount, SiC generation temperature, Si by CVD method
It goes without saying that the density and thickness of the C film, the method of cleaning the intermediate product, the type of cleaning agent, and the like are not limited to the present embodiment.

FIG. 1 is a flow chart showing the manufacturing process of the susceptor for vapor phase growth of the present invention.

A silicon supply source is selected from Si, Si ₃ N ₄ , SiO ₂ , SiO, etc. as a silicon-containing compound, mixed well with graphite powder, uniformly dispersed, and then formed into a desired shape.

Here, if the binder is added to the graphite powder, the reaction with silicon is promoted, and a denser network structure is obtained, which is a preferable result.

Self-sintering carbon powder, for example, cerafite, etc., may be used as raw material powder as graphite.

In addition, the quantitative ratio of the silicon-containing compound mixed and dispersed in the graphite powder is determined with respect to the graphite in the obtained susceptor substrate.
And prospect the amount of SiC is 0.5~15wt%.

No improvement in adhesion was observed at less than 0.5 wt%,
Above, workability becomes difficult. FIG. 2 shows the effect of the SiC content on the processing time. The processing cost of molding as a jig increases sharply when SiC is mixed at 15 wt% or more.

The molding method of the mixture is preferably a rubber press method or a molding method.

Next, the susceptor substrate molded into the target shape is heated and fired at 1300 ° C. or more, preferably 1300 to 2200 ° C., and Si, Si
₃ N _4, SiO _2, SiO is accounted to perform the Si + C → SiC becomes reacting the SiC, embedding SiC in the graphite.

The susceptor substrate, in which SiC is uniformly dispersed in graphite by baking, is chemically cleaned by baking with a hydrochloric acid gas in a heated state to remove impurities, and the SiC is removed by a normal CVD method.
Is deposited on a susceptor substrate to form a film.

At this time, since the SiC film formed by the CVD method grows with the SiC distributed on the susceptor substrate surface as a nucleus, not only the CVD operation is efficiently performed, but also the SiC film adheres firmly to the susceptor substrate surface, Phenomena such as peeling and cracking at the boundary surface are suppressed.

At the same time, considering the cross section perpendicular to the susceptor substrate surface, the concentration gradient from the susceptor substrate to the SiC film is relaxed by SiC embedded in the graphite, and the difference in thermal expansion coefficient on the fault plane is canceled out and uniformized. The thermal stability of the susceptor during the process is improved.

FIG. 3 shows the distribution of the average thermal expansion coefficient sampled from the susceptor for vapor phase growth of the present invention.

It is clear that the average thermal expansion coefficient distribution converges to a narrow range as shown.

〔The invention's effect〕

According to the susceptor for vapor phase growth of the present invention and the method for manufacturing the same, a susceptor substrate composed of only graphite of a conventional product and a
Eliminates physical fractures that were destined between the coatings, and in particular, uniformized the coefficient of thermal expansion, thereby avoiding cracks, peeling, and other phenomena that often occur in conventional products. Susceptors can now be supplied.

[Brief description of the drawings]

FIG. 1 is a flow chart showing a manufacturing process of the susceptor for vapor phase growth of the present invention, and FIG.
The effect of the SiC content is shown, and FIG. 3 shows the distribution of the average thermal expansion coefficient sampled from the susceptor for vapor phase growth of the present invention.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code Agency reference number FI Technical display location C04B 35/52 C04B 35/52 B

Claims (2)

(57) [Claims] An SiC coating is formed on a surface of a susceptor substrate composed of graphite and SiC containing 0.5 to 15 wt% of SiC with respect to graphite by a CVD method using SiC distributed on the surface of the susceptor substrate as a nucleus. Susceptor for vapor phase growth. 2. A graphite powder and a silicon-containing compound containing no group III or group V element are mixed, molded, and reacted under a high-temperature inert atmosphere of 1300 ° C. or higher or a reduced-pressure atmosphere.
On the surface of a susceptor substrate composed of graphite and SiC obtained by producing 0.5 to 15 wt% of SiC with respect to graphite,
2. The method for producing a susceptor for vapor phase growth according to claim 1, wherein a SiC film is formed by VD using SiC distributed on the surface of the susceptor substrate as a nucleus.