JPS6285425A - Vapor growth apparatus - Google Patents

Abstract

PURPOSE:To grow a semiconductor of high purity even if used in high temperature growing step using strong reactive reaction gas by coating the susceptor of a vapor growth apparatus with a porolytic boron nitride. CONSTITUTION:A susceptor substrate 5 is sealed in a quartz tube, boron trichloride and ammonia are supplied, thermal decomposition vapor growth reaction is proceeded at high temperature under low pressure to form a pyrolytic boron nitride layer approx. 10Xm thick on the substrate 5 to form a susceptor 6. Since it is necessary to bring the thermal expansion coefficient of the substrate 5 substantially into coincidence with that of the boron nitride at this time, the substrate material having 3.5X10<-6> per one degree of thermal expansion coefficient is used. Thus, since it is coated with the boron nitride, a semiconductor of high purity can be grown even is used in high temperature growing step using strong reactive reaction gas.

Description

Detailed Description of the Invention [Summary] A gas phase carbon susceptor coated with pyrolytic boron nitride, which is chemically stable even at high temperatures of about 1,000°C and has a low possibility of gas release. This is a growth device that can grow high-purity semiconductors in a vapor phase.

[Industrial application field]

The present invention relates to a vapor phase growth apparatus. In particular, the present invention relates to a vapor phase growth apparatus that can grow high-purity semiconductors even when a high-temperature growth process using a highly reactive reaction gas is required, such as in a metal-organic CVD method.

[Conventional technology]

FIG. 3 shows a structural diagram of an example of a horizontal vapor phase growth apparatus according to the prior art. In the figure, l is a quartz reaction tube, and in the figure, a reaction gas is supplied from the left, flows to the right, and is discharged from the right end.

2 is a heating device, and there are various methods such as an electric heating method and a high frequency induction heating method. 3 is a susceptor that supports the substrate 4, and is a carbon acid.

The reason why carbon is used as a material for the susceptor is that carbon is chemically stable, has a large heat conduction capacity, and is suitable for both electric heating and high-frequency induction heating.

[Problem that the invention seeks to solve]

However, carbon absorbs a small amount of gas and releases it under high vacuum and high temperature.
At high temperatures of 0°C, there is some reaction with highly reactive gases. For example, it reacts to some extent with carbon tetrachloride, aluminum, trimethyl gallium, triethyl gallium, etc., which are widely used in metal organic CVD methods, etc., so there is a risk of reducing the purity of the grown semiconductor.

An object of the present invention is to eliminate this drawback and provide a vapor phase growth apparatus that can grow high-purity semiconductors even when used in high-temperature growth processes using highly reactive reaction gases. There is a particular thing.

[Means for solving problems]

The means taken by the present invention to achieve the above object is to coat the susceptor 6 of the vapor phase growth apparatus with pyrolytic boron nitride.

[Effect]

Pyrolytic boron nitride is a polycrystalline form of polon nitride produced using a pyrolytic vapor phase growth method under high temperature and low pressure. It is easy to use, is chemically stable even at high temperatures, is oxidation resistant, has high mechanical strength even at high temperatures, and has low gas absorption and therefore low possibility of gas release. has.

Therefore, the present invention provides a carbon susceptor with a thickness of 10 pm.
It was decided to coat it with a certain amount of pyrolytic boron nitride.

In addition, since the growth temperature of semiconductors is generally about 600 to 1,000 degrees Celsius, the susceptor for a vapor phase growth apparatus is exposed to thermal cycling, so consideration must be given to the coefficient of thermal expansion. Pyrolytic boron nitride has a thermal expansion coefficient that differs by about 20:l between its growth direction and the direction perpendicular to the growth direction (direction forming the same plane), with the former having a coefficient of thermal expansion of 3.8X lo- per degree temperature. 5, and the latter is 1.5 to 1.9X 10-6 per degree of temperature.

Therefore, it is desirable to use carbon whose coefficient of thermal expansion is on the order of 10<-6 >per degree temperature.

〔Example〕

Hereinafter, a vapor phase growth apparatus according to an embodiment of the present invention will be further described with reference to the drawings.

Referring to FIG. 2, a susceptor base material 5 is manufactured by cutting graphite into the shape shown. The dimensions should be commensurate with the dimensions of the planned semiconductor wafer. For example, if a 2-inch circular wafer is planned, one piece of the upper base should be 60 to 80 mm wide, the lower base should be 60 to 80 mm x 80 to 100 mm, and the height should preferably be a trapezoid of about 20 mm. The reason why the trapezoid shape with the slope of the oblique side is about 30° is to prevent gas from becoming turbulent, and the reason why the height is relatively high is to ensure heat capacity.

This susceptor base material 5 is enclosed in a quartz tube, poron trichloride and ammonia are supplied, and a pyrolytic vapor phase growth reaction is advanced at high temperature and low pressure to form a pyrolytic boron nitride layer on the surface of the susceptor base material 5. The susceptor 6 is formed by forming the susceptor 6 to a thickness of about 10 IL. At this time, the coefficient of thermal expansion of the susceptor base material 5 is that of pyrolytic boron nitride (see FIG. 1).The susceptor 6 is placed in the reaction tube 1 made of quartz.

In vapor phase growth, the semiconductor substrate 4 is placed on the susceptor 6, a reaction gas is supplied, and the heating device 2 is operated.

When the pyrolytic boron nitride coated on the susceptor 6 is grown into graphite, it can be easily made to high purity, is chemically stable even at high temperatures, has oxidation resistance, and is resistant to high temperatures. It has characteristics such as high mechanical strength, low gas absorption, and therefore low possibility of gas release.
High purity semiconductors can be grown even when the reaction gas is highly reactive and even when the growth temperature is high.

〔Effect of the invention〕

As explained above, when the susceptor of the vapor phase growth apparatus according to the present invention is grown on graphite, it is easy to make it highly pure, it is chemically stable even at high temperatures, and has oxidation resistance. It is coated with pyrolytic boron nitride, which has high mechanical strength even at high temperatures and has low absorption of gas, so there is little possibility of gas release, so it can handle highly reactive reactive gases. For example, high-purity semiconductors cannot be grown even when used in high-temperature growth processes using carbon tetrachloride, aluminum, trimethyl gallium, triethyl gallium, etc., which are widely used in metal organic CVD methods, etc. can.

[Brief explanation of drawings]

FIG. 1 is a perspective view of a susceptor of a vapor phase growth apparatus according to an embodiment of the present invention. FIG. 2 is a configuration diagram of a vapor phase growth apparatus according to an embodiment of the present invention. FIG. 3 is a configuration diagram of a vapor phase growth apparatus according to the prior art. 1...Quartz reaction tube, 2...Heating device, 3.Susceptor according to the conventional technology, 4. - fist substrate, 5.1 Susceptor base material according to the wood invention, 6...Regarding the wood invention Susceptor.

Claims (1)

[Claims] A vapor phase growth apparatus having a carbon susceptor (6) coated with pyrolytic boron nitride.