JPH0799161A - Susceptor and its manufacture - Google Patents

Abstract

PURPOSE:To provide a susceptor in which no pore exists on the surface and which does not produce impurities by eliminating a difficult point in conventional techniques. CONSTITUTION:A susceptor is covered with a polycarbodiimide resin which has been carbonized. The manufacturing method of the susceptor is constituted in such a way that the susceptor is covered with the polycarbodiimide resin and that the polycarbodiimide resin is carbonized in an inert atmosphere.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a susceptor used for vapor phase epitaxial growth of a compound semiconductor (using indium, gallium, arsenic and phosphorus) and a method for producing the same, more specifically, a surface. The present invention relates to a susceptor in which pores are eliminated and impurities are not generated, and a method for manufacturing the susceptor.

[0002]

BACKGROUND OF THE INVENTION vapor-phase epitaxial growth, CVD method (C hemical V apor D epositio
Also called n), it is a kind of thin film growth technology in the manufacturing process of semiconductor devices, and is a method of directly growing a thin film on a semiconductor substrate by utilizing a chemical reaction in a gas phase.

In the above vapor phase epitaxial growth,
Since a thin layer of a semiconductor material is epitaxially formed on a semiconductor substrate by a thermal decomposition reaction of a gas phase component or a hydrogen reduction reaction at a high temperature, it is necessary to heat the semiconductor substrate at that time. A method has been adopted in which the semiconductor substrate is mounted on a heating substrate as a susceptor and the semiconductor substrate is heated through the susceptor.

When the vapor phase epitaxial growth is performed as described above, the performance of the obtained epitaxial layer is governed by the material of the susceptor, so the material of the susceptor can be said to be an extremely important factor.

Conventionally, silicon, molybdenum, tungsten, graphite and the like have been used as the material of the susceptor, but all of these materials have poor stability at high temperature and have a defect in purity, which is satisfactory. It wasn't the material that should be done. That is, for example, since graphite has pores, it is easy to adsorb gas, and therefore harmful gas is diffused during operation. However, there were drawbacks such as adversely affecting the product.

[0006]

Therefore, at present, a graphite material coated with a silicon carbide (SiC) film by the CVD method is used as the material of the above susceptor. However, the substrate in this graphite material is used. Since there is a difference in the coefficient of thermal expansion between the graphite and the silicon carbide coating of
When used at high temperatures (1300 to 1700 ° C.), there is a problem that cracks occur and the semiconductor is contaminated with impurities.

The present invention has been made in order to solve the above-mentioned drawbacks of the prior art and to provide a susceptor having no pores on the surface and generating no impurities.

[0008]

In order to achieve the above object, the structure of the susceptor adopted by the present invention is characterized in that it is coated with a carbonized polycarbodiimide resin. The constitution of the method for producing a susceptor adopted by the present invention to achieve the object is characterized in that the susceptor is coated with a polycarbodiimide resin, and then the polycarbodiimide resin is carbonized in an inert atmosphere. .

That is, the present inventors focused on a polycarbodiimide resin, which is a resin having a high carbon content after firing and carbonization and a high yield, and carbonizing this resin to coat a graphite susceptor. Then, the idea that a release of the graphite powder was not observed and a susceptor without open pores could be obtained, and further research was conducted, and as a result, the present invention was completed.

The present invention will be described in detail below.

The susceptor to be used in the present invention means, in vapor phase epitaxial growth as described above, when a semiconductor substrate is heated in order to epitaxially form a thin layer of a semiconductor material on the semiconductor substrate, the semiconductor thereon. A heated substrate used to mount a substrate.

In the present invention, one of the above susceptors made of graphite is coated with a carbonized polycarbodiimide resin.

The above-mentioned polycarbodiimide resin itself is well-known, or can be produced in the same manner as well-known ones [US Pat. No. 2,941,95].
6, Japanese Patent Publication No. 47-33279, J. Or
g. Chem. , 28 , 2069-2075 (196
3) Chemical Review l98l, vo
l. 8l. No. 4, 619 to 62l, etc.}, for example, it can be easily produced by a condensation reaction involving decarbonization of an organic diisocyanate in the presence of a carbodiimidization catalyst.

The organic diisocyanate used for producing the above polycarbodiimide resin may be of any type such as aliphatic type, alicyclic type, aromatic type and aromatic-aliphatic type. Used alone, or
You may use it as a copolymer combining 2 or more types.

Thus, the polycarbodiimide resin used in the present invention has the following formula -RNN = C = N- (wherein R in the formula represents an organic diisocyanate residue).
The homopolymers or copolymers of at least 1 type of repeating unit represented by

As R in the above formula, which is an organic diisocyanate residue, an aromatic diisocyanate residue is particularly preferable (here, the organic diisocyanate residue is obtained by removing two isocyanate groups (NCO) from the organic diisocyanate molecule). I say the rest). The following can be mentioned as specific examples of such a polycarbodiimide resin.

[Chemical 1]

In each of the above formulas, n is 10 to 10,0.
It is in the range of 00, preferably in the range of 50 to 5,000, and the end of the polycarbodiimide resin may be blocked with monoisocyanate or the like.

The above polycarbodiimide resin can be obtained as a solution as it is or as a powder precipitated from the solution, and the polycarbodiimide resin thus obtained is a liquid obtained polycarbodiimide resin.
It can be used as it is as a coating liquid, or in the case of a polycarbodiimide resin obtained as a powder, it may be used as a coating liquid after being dissolved in a solvent and made into a liquid form.

In the present invention, first, a coating film is formed on the surface of the susceptor with the coating liquid containing the above polycarbodiimide resin. The method for forming the coating may be any method such as vacuum impregnation, ultrasonic impregnation, brush coating, spraying, etc., and is not particularly limited. When forming this coating, part of the coating solution containing the polycarbodiimide resin penetrates into the open pores of the graphite.

The susceptor having a film formed on its surface is
After that, it is dried at a temperature of 60 ° C. to 300 ° C., for example.

Then, the susceptor having the polycarbodiimide resin film formed on the surface thereof as described above is heated,
By carbonizing the polycarbodiimide resin,
The desired susceptor of the present invention can be obtained. This carbonization step is performed in an inert atmosphere such as vacuum or nitrogen gas, and the final firing temperature at that time is 50
It is 0 ° C to 3000 ° C.

As described above, since the obtained susceptor of the present invention is coated with the carbonized polycarbodiimide resin, the open pores of the graphite are completely filled, and the graphite powder is dense and has no cracks. It is a good thing with no departure.

Next, the present invention will be described in more detail with reference to examples.

[0024]

【Example】

Example Mixture of 2,4-tolylene diisocyanate / 2,6-tolylene diisocyanate (80:20) (TDI) 5
In 500 ml of tetrachloroethylene, 4 g of carbodiimidization catalyst (1-phenyl-3-methylphosphorene oxide) was added. A polycarbodiimide resin solution was obtained by reacting with 12 g at 120 ° C. for 4 hours.

Separately from this, a disk type susceptor having a diameter of 20 cm was prepared using isotropic graphite (CIP product, density 1.8) made by Toyo Tanso.
5 g / cm ³ ), and these graphite susceptors were impregnated with a polycarbodiimide resin solution and applied, and the solvent was dried for 10 minutes at 60 ° C. and 10 minutes at 120 ° C.
Heat treatment was performed at 00 ° C. for 10 minutes. Then in vacuum 2000
An example of the obtained susceptor of the present invention, which was carbonized at ℃, was set in an international electric small-sized epitaxial growth apparatus, and a durability test consisting of the following processes was performed using silane gas. The results are shown in Table 1. I Set silicon wafer II Epitaxial growth (105 ° C, 1 hour) III Cooling evaluation IV Etching (HCI gas, 100 ° C, 1 hour)

Comparative Example A SiC film was attached to the graphite susceptor prepared in the example by the CVD method, and a durability test was conducted in the same manner as in the example. The results are shown in Table 1.

[Table 1]

[0027]

As shown in Table 1 above, according to the present invention, it was possible to obtain a good quality susceptor without cracking unlike the SiC-coated comparative example.

Claims (6)

[Claims] 1. A susceptor coated with a carbonized polycarbodiimide resin. 2. The susceptor according to claim 1, wherein the susceptor made of graphite is coated with the carbonized polycarbodiimide resin. 3. The susceptor according to claim 1, wherein a part of the carbonized polycarbodiimide resin penetrates inside the member. 4. A method for producing a susceptor, which comprises coating the susceptor with a polycarbodiimide resin and then carbonizing the polycarbodiimide resin in an inert atmosphere. 5. The method for manufacturing a susceptor according to claim 4, wherein the susceptor is made of graphite. 6. Carbonization at 500 ° C. in an inert atmosphere
The method for producing a susceptor according to claim 4, wherein the method is performed in a temperature range of ˜3000 ° C.