JP2628394B2 - Susceptor - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vertical vapor phase growth apparatus used for manufacturing a semiconductor wafer, and more particularly to an improvement of a susceptor for supporting a semiconductor wafer for high frequency induction heating of a semiconductor wafer. .

2. Description of the Related Art Various types of vertical vapor deposition apparatuses are used in the semiconductor industry.

Generally, a vertical vapor deposition apparatus includes a disk-shaped susceptor in a quartz or stainless steel furnace. A high-frequency coil is provided below the susceptor, and the susceptor is heated by the coil. A semiconductor substrate wafer is placed on a susceptor and heated by heat transfer from the susceptor.
Then, the raw material gas is guided into the furnace and injected onto the susceptor. The processing is performed while rotating the susceptor around the central axis.

The conventional susceptor has a solid carbon substrate coated with a SiC coating.

Problems to be Solved by the Invention In a susceptor in which a surface of a solid carbon substrate is coated with a SiC film, the following problems have been encountered.

1) The susceptor was likely to have uneven temperature due to uneven heating by the high frequency coil. For example, when heated to 1050 ° C., there was a temperature difference of about 10 ° C. between the central part and the outer part of the susceptor. In that case, the epitaxial process was not performed well, and the wafer was likely to have defects.

2) If the heating rate is high, the susceptor may be cracked, and the service life of the susceptor is not sufficient.

3) The susceptor may be warped during heating, and the quality of the wafer may be degraded.

It is an object of the present invention to provide a susceptor which can improve the quality of a wafer and has a long life by solving the above-mentioned drawbacks of the prior art.

Means for Solving the Problems In order to achieve the above-mentioned object, the present invention provides a susceptor for a semiconductor wafer high-frequency induction heating process for induction-heating a carbon substrate at a high frequency, wherein the carbon substrate comprises an upper plate,
It is composed of a lower member forming a hollow portion between the upper plates, and an opening communicating with the hollow portion is formed only on the lower surface of the lower member of the carbon substrate. A susceptor characterized in that the entire inner and outer surfaces of the carbon substrate including the inner surface of the hollow portion are covered with a SiC film.

BEST MODE FOR CARRYING OUT THE INVENTION The susceptor of the present invention has a carbon substrate having a hollow structure,
SiC not only on the outer surface but also on the inner surface of the hollow part
The membrane is covered.

In the present invention, a void (hollow portion) is provided inside the susceptor, and both the inner surface and the outer surface of the hollow carbon substrate are coated with the SiC film. The SiC film is coated by a CVD method or the like.

The carbon substrate includes an upper plate and a lower member (a lower plate and a rib in the illustrated example) forming a hollow portion between the upper plate and the upper plate.

Only the lower surface of the lower member of the carbon base is provided with a hole communicating with a gap in the carbon base. The processing gas supplied onto the wafer is usually exhausted from the lower part of the furnace, but the following advantages are obtained by providing a hole communicating with the hollow portion of the susceptor only on the lower surface of the lower member of the susceptor. That is, the impurities adsorbed on the carbon substrate are discharged from the holes, and are immediately discharged together with the processing gas. Therefore, the impurities do not reach the wafer placed on the susceptor and do not adversely affect the wafer. However, when the holes are provided, it is necessary to coat the inner surface of the carbon substrate with the SiC film.

It is desirable to reinforce the carbon substrate with carbon fibers.
Cracking during heating can be reduced by reinforcing with carbon fibers.

The thickness of the carbon substrate is desirably 0.1 to 1.5 times the internal space. If the thickness of the carbon substrate is less than 0.1 times the voids, there is a disadvantage that the uniformity of the surface is reduced.
If the ratio is more than 1.5 times, deformation may cause slip failure or variation in resistance value, resulting in an inconvenience that the yield of the wafer is reduced.

 It is preferable to provide a rib in the gap to increase the strength.

Embodiments Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 shows a vertical vapor phase growth apparatus whose main part is shown, having a susceptor 10 according to the present invention. The susceptor 10 includes an upper plate 9 and a lower member (a rib 7 and a lower plate 8 in the illustrated example). The upper plate 9 and the lower plate 8 are made of a carbonaceous molded body containing carbon fibers, and the surfaces thereof are coated with a SiC film. SiC
The film is coated on both surfaces of the upper plate 9 and the lower plate 8 by the CVD method, and the film thickness is, for example, 80 μm.

The upper plate 9 is a disk-shaped flat plate, and its upper surface is a wafer mounting surface on which the semiconductor wafer 20 is mounted.

The lower plate 8 is a disk-shaped flat plate having a rib 7. Rib 7
Are arranged concentrically, but ribs are arranged radially as appropriate. The lower plate 8 is provided with a number of holes 12.

The upper plate 9 and the lower plate 8 are joined with a thermosetting resin-based adhesive. A gap (hollow portion) 6 is formed between the upper plate 9 and the lower plate 8 and bounded by the ribs 7. The hole 12 communicates with the hollow portion 6.

The susceptor is rotatably supported in the furnace by a support member.

The gas supply pipe 11 is provided inside the support member 14. At the upper end of the gas supply pipe 11, a number of gas discharge holes 15 are provided. The raw material (epitaxial) gas is supplied from the lower end of the gas supply pipe 14 (arrow A), and is discharged from the gas discharge hole 15 onto the wafer 20 (arrow B).

A gas exhaust pipe 16 is provided below the susceptor 10, from which the source gas is exhausted outside the furnace. Impurities generated from inside the susceptor 10 by heating are released downward through the holes 12 of the susceptor 10 (arrow D), and are discharged from the gas exhaust pipe 16 together with the raw material gas.

A spiral (or concentric) high-frequency coil 13 is disposed below the susceptor 12, and heats the wafer via the susceptor.

Note that portions other than the susceptor of the vapor phase growth apparatus can adopt a conventional configuration.

A wafer processing experiment was performed using the apparatus shown in FIG. When the inside of the furnace was heated to 1050 ° C., the temperature difference between the center and the outside of the upper surface of the susceptor was about 1 ° C. It is considered that this is because only the upper surface of the susceptor is heated by the radiant heat by providing the gap in the susceptor. As described above, by reducing the temperature unevenness on the upper surface of the susceptor, the wafer processing can be performed satisfactorily, and the defect rate of the wafer can be reduced.

Note that the present invention is not limited to the above-described embodiment. For example, a counterbore for mounting a wafer may be provided on the upper surface of the susceptor.

Effects of the Invention According to the present invention, the susceptor has a hollow structure, so that high-frequency induction heating of the carbon substrate and the action of the hollow structure can reduce uneven temperature on the wafer mounting surface on the upper surface of the susceptor. Therefore, the defect occurrence rate of the wafer can be reduced.

Such an effect becomes more remarkable by coating both the outer surface and the inner surface of the hollow susceptor substrate with the SiC film. As a result, the defect occurrence rate can be further reduced.

If holes are provided only on the lower surface of the carbon substrate, the influence of the impurity gas can be further reduced.

When the susceptor substrate is reinforced with carbon fibers, the cracking phenomenon during heating can be reduced. Further, the deformation of the susceptor can be reduced by providing the rib.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a part of a vertical vapor phase growth apparatus provided with a susceptor for high frequency induction heating of a semiconductor wafer according to the present invention. 6 Air gap 10 Susceptor 12 Hole 20 Wafer

 ──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Haruo Tazoe 378 Oguni-cho, Oguni-machi, Oguni-machi, Nishiokitama-gun, Yamagata Prefecture Oguni Works, Toshiba Ceramics Co., Ltd. (56) References JP-A-1-290520 (JP, A) Sho 63-58819 (JP, A)

Claims (1)

(57) [Claims] 1. A susceptor for high-frequency induction heating of a semiconductor wafer for induction heating a carbon substrate at a high frequency, wherein the carbon substrate comprises an upper plate and a lower member forming a hollow portion between the upper plate. An opening communicating with the hollow portion is formed only on the lower surface of the lower member, and the entire inner and outer surfaces of the carbon substrate including the outer surface of the carbon substrate and the inner surface of the hollow portion are SiC films. A susceptor characterized by being coated with: