JP3810752B2 - Vapor growth apparatus and vapor growth method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention, a semiconductor wafer in the reaction chamber was retained by the wafer holding plate, the heater is provided below the wafer which is retained in the wafer holding plate, the gas phase is grown in vapor phase on the surface of the wafer in a heated state The present invention relates to a growth apparatus and a vapor phase growth method .
[0002]
[Prior 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 heated by a heating element disposed below the wafer holding member to form a vapor 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. In addition, a dish-shaped reflector is disposed above, and a heating element is accommodated therein, and a soaking plate is attached to the upper end. Further, a hollow rotary shaft is provided so as to surround the hollow cylindrical body, and a dish-like support body is attached to the upper end of the hollow rotating body so as to surround the reflector and the upper end is positioned above the heat equalizing plate. A ring-shaped wafer holding plate is fitted to the upper end. A counterbore is formed on the inner peripheral side of the wafer holding plate, and the wafer is placed therein.
[0003]
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 a source gas such as dichlorosilane and a carrier gas such as hydrogen is introduced from a gas introduction port to perform vapor phase growth. . At this time, the wafer is heated at about 1150 ° C.
[0004]
[Problems to be solved by the invention]
The conventional vapor phase growth apparatus was provided with a dish-shaped Mo reflector on the lower side of the heater. However, there was a drawback that the heater was contaminated and the life of the heater was greatly reduced. . On the other hand, when the reflecting plate is made of SUS or quartz, it cannot be washed with an HNO ₃ —HF aqueous solution after the heat treatment. This is because the surface of the reflector is eroded by the HNO ₃ —HF aqueous solution.
[0005]
The object of the present invention is that the reflection efficiency does not decrease as low as before even after the heat treatment, and the reflection efficiency can be improved by cleaning the surface with an aqueous HNO ₃ —HF solution as necessary to return the surface to the original smooth state. To provide a vapor phase growth apparatus and a vapor phase growth method using a plate.
[0006]
[Means for Solving the Problems]
The gist of the present invention is the vapor phase growth apparatus according to claims 1 to 3 and the vapor phase growth method according to claims 4 to 5 .
[0007]
【The invention's effect】
In the present invention, the reflecting plate is formed of glassy carbon. When the reflecting plate is made of glassy carbon, the surface is in a smooth state (so-called “smooth” state) and the reflection efficiency is good. In particular, when the surface roughness of the reflecting plate is Ra 0.001 to 0.05 μm, the reflection efficiency becomes remarkable.
[0008]
Even when the surface of the reflecting plate is not smooth due to the heat treatment and the reflection efficiency is lowered, the surface can be easily cleaned with an aqueous HNO ₃ —HF solution because it is formed of glassy carbon. As a result, the surface of the reflector is again in a good smooth state.
BEST MODE FOR CARRYING OUT THE INVENTION
The vitreous carbon used in the present invention is hard carbon having an external 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 1.60 g / cm ³ , and if the bulk density is less than 1.50 g / cm ³ , the number of pores as a reflector increases and the reflection efficiency deteriorates. On the other hand, if it exceeds 1.60 g / cm ³ , it is no longer hard carbon, and particles are likely to be generated, which deteriorates the yield of the wafer. When the bending strength is 100 MPa or more and less than 100 MPa, the reflector is bent and cracked during processing of several hundred wafers. Further, the specific resistance is 4000 to 4400 μΩcm, the open porosity is 0.1% or less, the Shore hardness is 100 or more, and the thermal conductivity is preferably 5 to 10 W / m · K as the reflector.
[0009]
An example of a method for producing a glassy carbon reflector will be described. First, a resin (for example, a furan resin or a phenol resin) as a raw material is formed into a predetermined shape, and then fired at 950 ° C. in a non-oxidizing atmosphere, whereby the resin can be made into glassy carbon. More specifically, it is polymerized while adding 0.1 part of a polymerization accelerator to a furan resin, and cast into a mold. This is temporarily processed after heat curing at 100 ° C. or lower. Thereafter, primary firing at about 1000 ° C. and secondary firing at about 2000 ° C. are performed in a non-oxidizing atmosphere. After secondary processing, the surface is polished to a mirror surface by diamond polishing. This is purified at 2000 ° C. or higher in a halogen-based gas atmosphere.
[0010]
The reflecting plate preferably has a surface roughness Ra of 0.001 to 0.05 μm at least on the surface facing the heater from the viewpoint of reflection efficiency. If it is less than Ra 0.001 μm, a significant difference in reflection efficiency will not be seen, and the processing cost will be several tens of times. If it exceeds Ra 0.05 μm, the surface roughness of the reflector after the heat treatment is lowered, and the reflection efficiency is remarkably lowered.
[0011]
【Example】
Embodiments of the present invention will be described below with reference to the drawings.
[0012]
In FIG. 1, a hollow cylindrical body 11 extending upward is attached to the lower surface of a base 10, and a heater support 12 is attached to the upper end thereof. A heater 16 is attached to the heater support 12 via an insulating rod 13, a reflector 14 and an insulating rod 15. The reflection plate 14 is made of the above-mentioned glassy carbon, and as is apparent from FIG. 1, is composed of a disc-shaped bottom portion and a cylindrical side portion integrally formed on the outer periphery thereof. It has a shape. The lower end of the hollow cylindrical body 11 is closed by a lid 18, and a power supply wiring 17 that passes through the lid 18 and is connected to the heater 16 is provided inside the hollow cylindrical body 11. The heater 16 can be rapidly heated to a high temperature of 1000 ° C. or higher.
[0013]
A hollow rotary shaft 20 is provided so as to surround the hollow cylindrical body 11, and the hollow rotary shaft 20 is rotatably attached to the base 10 by a bearing 21 regardless of the hollow cylindrical body 11. The hollow rotary shaft 20 is attached with a pulley 22 and is driven to rotate by a motor (not shown) via a belt 23.
[0014]
The upper end of the hollow rotating 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, and a carbon support disk 27 is fixed to the upper end of the hollow rotating shaft 20 via a key 26. ing. A support ring 28 made of quartz glass, carbon or ceramics is attached to the support disk 27 so as to be integrally rotatable with the support disk 27.
[0015]
The support ring 28 surrounds the outer periphery of the heater support 12, the reflecting plate 14, and the heater 16, and extends upward from the heater 16.
[0016]
A step 31 is formed at the upper end of the support ring 28, a ring-shaped wafer holding plate 32 is fitted into the step 31, and the wafer W is placed in a step 33 formed near the inner periphery of the upper surface of the wafer holder 32. Is supposed to hold. The wafer W supported by the wafer holder 32 is placed so as to have a predetermined distance from the heater 16.
[0017]
On the outer periphery of the support ring 28, a cylindrical heat insulating cylinder 40 is disposed concentrically with a predetermined gap. The heat insulating cylinder 40 is made of quartz glass or glassy carbon.
Next, the operation of the above vapor phase growth apparatus will be described.
[0018]
Power is supplied to the heater 16 to heat it, and the hollow rotating 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.
[0019]
The wafer holder 32 supports the wafer W so as to keep the interval 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 from the center of the wafer W to the outer periphery. It has the role which makes uniform temperature distribution over the whole area.
[0020]
When the wafer W is rapidly heated to a predetermined vapor growth temperature, for example, 1000 ° C. or more, vapor deposition is performed by causing the reaction gas to flow from the upper side toward the wafer W in FIG. At this time, a 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 was compared with glassy carbon 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 could be used even after at least 1000 wafers.
[0021]
In particular, when the glassy carbon reflector of the present invention is used in a vapor phase growth apparatus capable of high-temperature heating for 90 seconds from 800 to 1150 ° C., the yield of the vapor phase growth film thickness is improved.
[Brief description of the drawings]
FIG. 1 is a schematic sectional view showing an embodiment of the present invention.
[Explanation of symbols]
14 Reflector 40 Thermal insulation cylinder

Claims (5)

A reaction chamber, a holder provided in the reaction chamber for holding the wafer, a heater provided below the holder, and a reflector provided below the heater for reflecting the heat of the heater In a vapor phase growth apparatus equipped with
A vapor phase growth apparatus characterized in that the reflecting plate is formed of glassy garbon having a bulk density of 1.50 to 1.60 g / cm ³ . The surface roughness of at least the surface of the reflector facing the heater is R a 2. The vapor phase growth apparatus according to claim 1, wherein the vapor phase growth apparatus is formed to have a thickness of 0.001 to 0.05 μm. The reflector has a bending strength of 100 Mpa or more, a specific resistance of 4000 to 4400 μΩcm, an open porosity of 0.1% or less, a Shore hardness of 100 or more, and a thermal conductivity of 5 to 10 W. / 2. The vapor phase growth apparatus according to claim 1, wherein the vapor phase growth apparatus is set to m · k. A reaction chamber in which a gas inlet is formed; a holder provided in the reaction chamber for holding a wafer; a heater provided below the holder; and a heat of the heater provided below the heater. And a reflector density of the reflector is 1.50 to 1.60 g. / cm ³ After the wafer is placed on the holding body, the wafer is heated by the heater, and the heat of the heater is directed toward the wafer by the reflector. A vapor phase growth method characterized in that a source gas is introduced from the gas introduction port while being reflected and heated to cause vapor phase growth on the surface of the wafer. 5. The vapor phase growth method according to claim 4, wherein the reflector is made of HNO. ₃ A vapor phase growth method characterized by washing with an HF aqueous solution.

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