JPH0693453A - Susceptor - Google Patents

Abstract

PURPOSE:To enable forming an uniform film on a wafer by constituting a susceptor of graphite having a specific positive reflectance of specific incident light and specific range of positive reflectance of the incident light. CONSTITUTION:The susceptor is constituted of graphite. The graphite has 0.5 to 1% positive reflectance R30 of 30deg incident light and the positive reflectance Rtheta of thetadeg incident light is in the range expressed by formula I. In formula I, theta is 30, 50 and 80. On the graphite, a coating film made of vitreous carbon and/or pyrolytic carbon is formed. Consequently, the peeling of a film deposited on the susceptor is eliminated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a susceptor suitable for use in vapor phase growth.

[0002]

2. Description of the Related Art Conventionally, as a susceptor for vapor phase growth, there is known one in which the surface of graphite or a graphite base material is coated with glassy carbon, pyrolytic graphite, a ceramic film or the like (for example, JP-A-64-47019). Issue).

[0003]

However, the above graphite material is liable to generate dust and has a C content.
When various CVD films such as a silicon oxide film and a silicon nitride film are formed on a wafer by VD, the heat applied to the susceptor by external heater heating or high frequency heating is not uniformly transferred to the wafer because the surface of the susceptor is rough. However, there is a problem that it is difficult to form a uniform film within a wafer or between wafers. On the other hand, the glass-like carbon coating does not have such a defect, but since the surface is flat, the CVD film deposited on the susceptor is easily peeled off, and there is a possibility that it is taken into the formed film. .

In order to solve the above problems, it has been proposed to change the surface roughness of the surface of the wafer contact portion and the surface other than that (Japanese Patent Laid-Open No. 146672/1993). Since it is necessary to mechanically roughen the surface after masking the surface other than the surface of the wafer, there is a problem in productivity.

An object of the present invention is to solve the above problems and to provide a susceptor in which a uniform film is formed on a wafer and the deposited CVD film is not peeled off.

[0006]

That is, the present invention has three features.
The susceptor is characterized in that the regular reflectance R30 of 0 deg incident light is 0.5 to 1%, and that the regular reflectance Rθ of θ deg incident light is composed of graphite in a range represented by the following equation. Further, the susceptor is characterized in that a film of glassy carbon and / or pyrolytic carbon is formed on the susceptor made of this graphite. 0.5 × (θ / 30) ² ≦ Rθ ≦ 1 × (θ / 30) ² (where θ is 30, 50, 80)

Explaining the present invention in more detail below, the graphite base material used in the present invention is not particularly limited, but the density is 1.65 g / cm ^{3 because} of the ease of film formation.
The above isotropic graphite is desirable.

There is a close relationship between the surface state of graphite and gloss, and generally, if the surface is flat, the specular reflectance increases, and if the number of pores increases, the diffuse reflection increases and the specular reflectance decreases. The smaller the incident angle, the stronger the influence of diffuse reflection on the decrease in the regular reflectance.

In order to form a uniform film on the wafer and prevent the deposited film from peeling off on the susceptor, many experiments have shown that the regular reflectance R30 of incident light of 30 deg is 0.5 to 1.
The present inventors have found that the graphite is a graphite having a regular reflectance Rθ of θ deg incident light in the range represented by the above equation.

That is, if R30 is less than 0.5%, it is difficult to form a uniform film, and if R30 is more than 1%, the deposited film is easily peeled off. On the other hand, when Rθ <0.5 × (θ / 30) ² , it is difficult to form a uniform film, and 1 × (θ / 30) ² <
At Rθ, the deposited film is easily peeled off.

Since making the surface of the susceptor flat to form a uniform film on the wafer and making the surface of the susceptor rough to prevent peeling of the deposited film make use of the contradictory properties, up to now. No susceptor with both characteristics was developed. However, the present inventors have found that the anchor effect between the susceptor and the deposited film largely depends not only on the surface roughness of the susceptor but also on the porosity of the susceptor. It is considered that this is because the raw material gas penetrates deeply into the susceptor through the pores of the susceptor and reacts with the susceptor to form a rooted CVD film.

The susceptor of the present invention having the above-mentioned graphite surface state is mechanically polished to have a specular reflectance higher than the above value, and then heated in air at a temperature of about 300 ° C. It can be obtained by oxidative consumption.

Generation of graphite dust can be reduced by forming a film of glassy carbon or pyrolytic carbon on the susceptor of the present invention made of the above graphite.

In order to form a film of glassy carbon or pyrolytic carbon, a method of dissolving and coating a pyrolyzed product of an organic polymer (for example, Japanese Patent Publication No. 52-39684), an organic polymer or a precursor thereof. A method of melting and coating (for example, JP-A-62-283807), a method of thermally decomposing a hydrocarbon vapor (for example, JP-A-64-9900) and the like can be adopted.

[0015]

EXAMPLES The present invention will be described in more detail with reference to Examples and Comparative Examples. Examples 1 to 4 Comparative Examples 1 to 4 The surface of a susceptor graphite base material for CVD (80 × 150 × 4 mm) having the shape disclosed in JP-A-3-146672 is mechanically polished to have different specular reflectances. After preparing several kinds of them, they were heat-treated in air at a temperature of 300 ° C. to manufacture susceptors having different regular reflectances shown in Table 1.

With respect to a part of the susceptor obtained as described above, polyvinyl chloride is pyrolyzed at 500 ° C. in a nitrogen atmosphere to produce a tar-like precursor, which is dissolved in trichloroethylene to obtain 10% by weight. After applying the solution, it is baked at a temperature of 1000 ° C. in a vacuum atmosphere.
A 5 μm glassy carbon coating was formed.

In order to evaluate the performance of the susceptor, a diffusion furnace type plasma CVD apparatus was used to set five 4-inch Si wafers in the susceptor and put them in a bell jar. High frequency 13.5
Apply 6MHz, use monosilane and ammonia as raw materials,
The film adhesion when depositing a silicon nitride film of about 1.2 μm on a Si wafer, the amount of foreign matter mixed in the film, and the uniformity of the film by microscopic observation were measured. The results are shown in Table 1.

The adhesive force is measured by pulling the SUS metal fitting and then peeling off the silicon nitride film after adhering the SUS metal fitting to the silicon nitride film with an epoxy adhesive to fix the sample. Therefore, the amount of foreign matter is
It was measured and evaluated by an optical microscope.

[0019]

[Table 1]

From Table 1, in the susceptor made of graphite satisfying the surface condition of the present invention, a uniform film is formed on the wafer,
Moreover, it can be seen that the adhesive force of the film deposited on the susceptor also increases. Further, the amount of foreign matter is reduced in the case of coating with glassy carbon.

[0021]

According to the susceptor of the present invention, a uniform film is formed on the wafer, and the film deposited on the susceptor can be eliminated.

Claims (2)

[Claims] 1. A specular reflectance R30 of 30 deg incident light is 0.5 to 1%, and the specular reflectance Rθ of θ deg incident light is composed of graphite having a range represented by the following equation. And a susceptor. 0.5 × (θ / 30) ² ≦ Rθ ≦ 1 × (θ / 30) ² (where θ is 30, 50, 80) 2. The susceptor according to claim 1, wherein the graphite is coated with glassy carbon and / or pyrolytic carbon.