JPH0963973A - Vapor growth device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a vapor growth device using a reflective plate of a structure, wherein the reflection efficiency of the reflective plate is not reduced as much as the reflection efficiency of a conventional reflective plate even after the plate is subjected to heating treatment and moreover, the plate is cleaned with an HNO3 -HF aqueous solution according to the need to return the surface of the plate to its former smooth state and the reflection efficiency can be improved. SOLUTION: In a vapor growth device of a structure, wherein a wafer is supported by a wafer support plate in the interior of a reaction chamber, a heater is provided under the lower part of the wafer supported by the wafer support plate and a thin film is vapor-grown on the surface of the wafer, a reflective plate 14, which reflects at least downward heat of the heater, is provided, a heat insulating cylinder 40 is provided in such a way as to encircle the outer periphery on the side of the heater and the plate 14 is formed of a glassy carbon.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention supports a semiconductor wafer by a wafer holding plate inside a reaction chamber, and a heater is provided below the wafer supported by the wafer holding plate so that the surface of the wafer is heated in a heated state. The present invention relates to a vapor phase growth apparatus for performing phase growth.

[0002]

2. Description of the Related Art A conventionally used vapor phase growth apparatus is disclosed in, for example, Japanese Patent Laid-Open No. 5-152207.
It is a vapor phase growth apparatus that is supported by a wafer holding member and is heated by a heating element arranged below the wafer holding member to form a vapor phase growth film on the wafer surface. For example, a hollow cylindrical body extending upward is attached to the lower surface of the base, and a heating element support is attached to the upper end thereof. Further, a dish-shaped reflecting plate is arranged above it, and a heating element is accommodated inside the reflecting plate, and a soaking plate is attached to the upper end. The upper end of the dish-shaped reflecting plate is located above the heat equalizing plate, and a ring-shaped wafer holding plate is fitted on this upper end. A counterbore is formed on the inner peripheral side of the wafer holding plate, and the wafer is placed in this.

In this vapor phase growth apparatus, a reduced pressure atmosphere of 50 to 400 Torr is formed in the reaction chamber, and a large amount of raw material gas such as dichlorosilane and carrier gas such as hydrogen are introduced from the gas introduction port to carry out vapor phase growth. Is done. At this time, the wafer is heated at about 1150 ° C.

[0004]

In the conventional vapor phase growth apparatus, a dish-shaped reflector made of Mo was provided under the heater. However, it causes impurity contamination of the heater and significantly extends the life of the heater. There was a drawback that it decreased. On the other hand, when the reflection plate is made of SUS or quartz, it cannot be washed with the HNO ₃ -HF aqueous solution after the heat treatment. This is because the surface of the reflection plate is eroded by the HNO ₃ -HF aqueous solution.

An object of the present invention is that the reflection efficiency does not decrease as much as before even after the heat treatment, and if necessary, HNO ₃ −
It is an object of the present invention to provide a vapor phase growth apparatus using a reflection plate that can improve the reflection efficiency by cleaning the surface with an HF aqueous solution to restore the original smooth state.

[0006]

The gist of the present invention is a vapor phase growth apparatus according to any one of claims 1 to 5 described above.

[0007]

According to the present invention, the reflector is made of glassy carbon, and the heat insulating tube is made of glassy carbon or quartz glass. When the reflecting plate is made of glassy carbon, its surface is in a smooth state (so-called "smooth" state), and the reflection efficiency is good. Especially, the surface roughness of the reflector is Ra 0.001 to 0.05 μ.
When it is set to m, the reflection efficiency becomes remarkable.

Even if the surface of the reflector is not smooth due to the heat treatment and the reflection efficiency is lowered, since it is made of glassy carbon, it is easy to use HNO ₃ -HF.
The surface can be washed with an aqueous solution. As a result, the surface of the reflection plate is in a good smooth state again.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION The glassy carbon used in the present invention is hard carbon having a glassy appearance, and can be produced, for example, by solid-phase carbonization of a thermosetting resin. Preferred glassy carbon has a bulk density of 1.50 to 1.6.
Was 0 g / cm ^3, the bulk density is less than 1.50 g / cm ^3, pores many becomes reflection efficiency deteriorates as a reflector. On the other hand, when it exceeds 1.60 g / cm ³ , it is not hard carbon and particles are apt to be generated to deteriorate the yield of wafers. Bending strength is 100 MPa or more, 1
If the pressure is less than 00 MPa, the reflecting plate will bend and break during the processing of hundreds of wafers. Furthermore, the specific resistance is 4000
˜4400 μΩcm, open porosity is 0.1% or less, Shore hardness is 100 or more, and thermal conductivity is 5˜5.
10 W / m · K is preferable as the reflector.

An example of a method for manufacturing a reflection plate made of glassy carbon will be described. First, a resin as a raw material (for example, a furan-based resin or a phenol-based resin) is molded into a predetermined shape, and then baked at 950 ° C. in a non-oxidizing atmosphere, whereby the resin can be made into glassy carbon. More specifically, 0.1 part of the polymerization accelerator is added to the furan-based resin to polymerize, and the mixture is cast into a mold. This is heat-cured at 100 ° C. or lower and then temporarily processed.
After that, primary baking at about 1000 ° C. and secondary baking at about 2000 ° C. are performed in a non-oxidizing atmosphere, and after secondary processing, mirror polishing is performed by diamond polishing. This is purified at 2000 ° C. or higher in a halogen-based gas atmosphere.

From the viewpoint of reflection efficiency, the reflecting plate has a surface of at least Ra 0.001 to 0.05 facing the heater.
The surface roughness is preferably μm. Ra 0.001μ
When it is less than m, there is no significant difference in reflection efficiency,
Moreover, the processing cost becomes several tens of times. Ra0.0
If it exceeds 5 μm, the surface roughness of the reflecting plate after heat treatment is lowered, and the reflection efficiency is remarkably lowered.

[0012]

Embodiments of the present invention will be described below with reference to the drawings.

In FIG. 1, a hollow cylindrical body 11 extending upward is attached to a lower surface of a base 10, and a heater support 12 is attached to an upper end of the hollow cylindrical body 11. Heater support 1
A heater 16 is attached to 2 via an insulating rod 13, a reflector 14 and an insulating rod 15. The reflecting plate 14 is formed of the above-mentioned glassy carbon, and as is apparent from FIG. 1, it is composed of a disc-shaped bottom portion and a cylindrical side portion integrally formed on the outer periphery thereof, which is a shallow container. It has a shape. The lower end of the hollow cylindrical body 11 is closed by a lid 18, and inside the hollow cylindrical body 11, a power supply wiring 17 penetrating the lid 18 and connected to a heater 16 is provided. Heater 16
Can be rapidly heated to high temperatures of 1000 ° C. and above.

A hollow rotary shaft 20 is provided so as to surround the hollow cylindrical body 11, and the hollow rotary shaft 20 has a bearing 21.
Allows the base 1 to rotate freely regardless of the hollow cylindrical body 11.
It is attached to 0. A pulley 22 is attached to the hollow rotary shaft 20, and the hollow rotary shaft 20 is rotationally driven by a motor (not shown) via a belt 23.

The upper end of the hollow rotary shaft 20 extends into a reaction chamber 25 formed above the upper surface of the base 10 by a bell jar 24 showing only a part of the hollow rotary shaft 20, and the upper end of the hollow rotary shaft 20 has a support disk 27 made of carbon via a key 26. Is stuck. Support disk 27
A support ring 28 made of quartz glass, carbon or ceramics is rotatably attached to the support disk 27 integrally therewith.

The support ring 28 surrounds the outer periphery of the heater support 12, the reflection plate 14 and the heater 16 and extends above the heater 16.

A step portion 31 is formed on the upper end of the support ring 28, and a ring-shaped wafer holding plate 32 is fitted in the step portion 31, and inside a step portion 33 formed near the inner circumference of the upper surface of the wafer holder 32. The wafer W is held on the wafer. The wafer W supported by the wafer holder 32 is placed so as to have a predetermined distance from the heater 16.

A cylindrical heat retaining tube 40 is concentrically arranged on the outer periphery of the support ring 28 with a predetermined gap. The heat insulating cylinder 40 is formed of quartz glass or glassy carbon.

Next, the operation of the above vapor phase growth apparatus will be described.

Power is supplied to the heater 16 to perform heating, and
The hollow rotary shaft 20 is rotated to rotate the wafer holder 32 and the wafer W. The wafer W and the wafer holder 32 are heated by the heater 16.

The wafer holder 32 supports the wafer W so as to keep the gap at a predetermined value, and is heated by the heater 16 to heat the outer periphery of the wafer W to suppress the temperature decrease of the outer periphery and to reduce the center of the wafer W. From the whole to the outer circumference,
It has the role of providing a uniform temperature distribution.

The wafer W is heated to a predetermined vapor deposition temperature, for example, 1
Figure 1 shows the reaction gas when rapidly heated to 000 ° C or higher.
In, the vapor phase growth is performed by flowing the wafer W from above toward the wafer W. At this time, the vapor phase growth film is formed not only on the surface of the wafer W but also on the surface of the wafer holder 32. When isotropic carbon and glassy carbon were compared as the material of the reflector, a duct was generated in the case of isotropic carbon, and the use of the first wafer had to be stopped. When a glassy carbon reflector was used, it was usable even after at least 1,000 wafers.

In particular, when the glassy carbon reflector of the present invention is used in a vapor phase growth apparatus capable of heating at a high temperature of 800 to 1150 ° C. for 90 seconds, the yield of vapor phase growth film thickness is improved.

[Brief description of drawings]

FIG. 1 is a schematic sectional view showing an embodiment of the present invention.

[Explanation of symbols]

 14 Reflector 40 Heat insulation tube

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Tadashi Ohashi 30 Soya, Hadano City, Kanagawa Prefecture Toshiba Ceramics Co., Ltd.Development Laboratory (72) Inventor Masayuki Shimada 2068-3 Ooka, Numazu City, Shizuoka Toshiba Machine Co., Ltd. (72) Inventor Shinichi Mitani 2068-3 Ooka, Numazu City, Shizuoka Prefecture Numazu Business Office, Toshiba Machine Co., Ltd. (72) Inventor, Kyoaki Honda 2068-3 Ooka, Numazu City, Shizuoka Prefecture Numazu Business Office, Toshiba Machine Co., Ltd.

Claims (5)

[Claims] 1. A vapor phase growth apparatus in which a wafer is supported by a wafer holder inside a reaction chamber, a heater is provided below the wafer supported by the wafer holder, and vapor growth is performed on the surface of the wafer in a heated state. 2. The vapor phase growth apparatus according to claim 1, wherein the heater is provided with at least a reflecting plate that reflects downward heat, and the reflecting plate is made of glassy carbon. 2. Of the surfaces of the reflector, at least the surface facing the heater has a Ra of 0.001 to 0.05 μm.
The vapor phase growth apparatus according to claim 1, having a surface roughness of m. 3. The vapor phase growth apparatus according to claim 1, wherein the heater can rapidly heat to a high temperature of 1000 ° C. or higher. 4. The glassy carbon has a bulk density of 1.5.
The vapor phase growth apparatus according to claim 1, which has a bending strength of 0 to 1.60 g / cm ³ and a bending strength of 100 MPa or more. 5. The vapor phase growth apparatus according to claim 1, wherein the reflection plate has a disk-shaped bottom portion and a cylindrical side portion, and the heater is arranged in a cylindrical space formed by these.