JP2003002781A - Member for producing semiconductor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve the problem caused by the difference between the thermal expansion of a C/C composite material and that of a SiC coated layer and to provide a member useful for easily producing even large-sized semiconductor materials. SOLUTION: In the member for producing semiconductor materials which is obtained by forming a SiC coating layer on a carbon fiber-reinforced carbon composite base material, the composite base material is subjected to CVI treatment for filling carbon, and a carbon coating layer formed by CVD treatment is interposed between the surface of composite base material and the SiC coating layer as an intermediate layer. The thermal stress is eliminated by the specific internal structure. Hence the member for producing semiconductors produced by the method mentioned above has excellent resistance to thermal shock, high mechanical strengths and chemical stability, and is suitable as a hot zone member and has high quality and exhibits dramatically prolonged service life in comparison with a conventional member.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a semiconductor manufacturing member. For example, the present invention is a radiation shield used in a pulling process of a semiconductor single crystal such as silicon, a heat insulating tube,
The present invention relates to a hot zone member such as a heat insulating plate.

[0002]

2. Description of the Related Art A member for semiconductor production is known in which a SiC coating layer is provided on a carbon fiber reinforced carbon composite substrate (C / C composite substrate). See, for example, Japanese Patent No. 3120884.

[0003]

This kind of semiconductor manufacturing member is apt to be deformed or cracked. In particular, when a radiation shield, a heat insulating cylinder, a heat insulating plate, etc. are used in the hot zone of the semiconductor single crystal pulling process, deformation and cracks are likely to occur due to repeated operations.

It has been considered that such deformation and cracks are mainly caused by thermal stress due to the difference in thermal expansion between the C / C composite substrate and the SiC coating layer. Patent No. 3120884
In the invention, a reinforcing layer is provided between the C / C composite base material and the SiC coating layer to solve this type of problem. However, in the invention of Japanese Patent No. 3120884, the manufacturing method for obtaining the desired characteristics is limited, and therefore, in the case of a large-sized member, inconvenience tends to occur in manufacturing.

The object of the present invention is to provide a C / C composite substrate and SiC.
It is an object of the present invention to provide a semiconductor manufacturing member that not only solves the problem caused by the difference in thermal expansion from the coating layer but also can easily manufacture a large-sized one.

[0006]

The solution means of the present invention is exemplified as follows.

(1) In a member for semiconductor production in which a SiC coating layer is formed on a C / C composite base material, the composite base material is CVI-treated and filled with carbon. A member for semiconductor production, wherein a carbon coating layer formed by a CVD process is interposed as an intermediate layer between the coating layer and the coating layer.

(2) The above-mentioned semiconductor manufacturing member, wherein the carbon coating layer is thicker than the SiC coating layer.

(3) The thickness of the carbon coating layer is 100 to 200.
The member for semiconductor production as described above, which is characterized in having a thickness of μm.

(4) The above-mentioned semiconductor manufacturing member, wherein the CVI-treated composite base material has a bulk density of 1.6 g / cm ³ or more.

(5) The thickness of the SiC coating layer is 50-100.
The above-mentioned semiconductor manufacturing member having a thickness of μm.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION The present inventor first conducted various experiments in order to solve the problems caused by the difference in thermal expansion between the C / C composite substrate and the SiC coating layer. For example, the surface of the carbon base material on which the SiC coating layer is formed has periodic irregularities, the thickness of the SiC film is reduced, the uniformity of the film thickness is improved, or the carbon base material is treated with CVI to form SiC. / S
It has a triple structure of iC + carbon / carbon.

Although various methods for buffering the thermal stress due to the difference in thermal expansion have been studied in this way, it has not been possible to reliably avoid deformation and cracks in the member.

Further, a carbon substrate not coated with SiC, a radiation shield made of a C / C composite substrate having high strength and high thermal shock resistance, a heat insulating cylinder and a heat insulating plate were tested respectively.

As a result, in the case of a carbon base material, SiC
When used in the hot zone like the coated carbon substrate,
Deformation or cracks occurred. In the case of C / C composite substrate,
Although no deformation was observed, SiO evaporated from the melt
The reactivity with gas was high, and cracking and peeling due to silicification occurred. From this, it was confirmed that in the case of a carbon base material, heat was an incentive to cause distortion and creep. Further, in the case of the C / C composite base material, it was confirmed that deterioration due to a chemical reaction was a problem.

Therefore, the present inventor has studied various materials and structures of semiconductor manufacturing members (especially, radiation shields, heat insulating cylinders and heat insulating plates) that are chemically stable, have high strength, and have high thermal shock resistance. C / C filled with carbon
A tight carbon coating layer is formed on the surface of the composite substrate by a CVD process, and a SiC layer is coated thereon to form a three-layer structure, thereby forming a thermally and chemically stable hot zone member. I have determined what I can do.

In the semiconductor manufacturing member according to the present invention, the matching of the thermal expansion coefficient is worse than that of the SiC-coated carbon base material, but the stress due to the difference in thermal expansion between the layers is absorbed by the C / C composite material of the base material. In the form, the thermal stability of the C / C composite substrate and the chemical stability of SiC are exerted.

According to the present invention, the C / C composite substrate is CVI
It has been processed. For example, the CVI-treated composite base material is one in which carbon is embedded in the base material by reducing the pressure from the back side of the base material and sucking carbon-based CVD gas. The surface of the base material is sufficiently densified, and is preferably a mirror surface. A carbon-based CV is formed on the surface of the base material thus densified.
After stacking the D films, a SiC-CVD coat is formed.

The surface of the C / C composite substrate is densified by CVI treatment in order to facilitate the formation of a dense carbon intermediate layer by the CVD treatment.

If the thickness of the carbon intermediate layer is less than 100 μm, the surface smoothness is insufficient and the durability of the SiC film is poor. On the other hand, when it exceeds 200 μm, the SiC film thickness becomes rather unstable and the durability deteriorates.

The thickness of the SiC coating layer may be sufficient to coat the underlying CVD carbon intermediate layer.

[0022]

[Example] Using a PAN-based high-strength type carbon fiber,
Molded by filament winding impregnated with phenol resin, lower inner diameter 350mm, upper inner diameter 750
mm, height 450 mm, thickness 7 mm truncated cone C / C
A radiation shield made of a composite substrate was created. This radiation shield was CVI treated. That is, the pressure is reduced from one side (for example, the back side or the inside) of the radiation shield made of the C / C composite substrate, and the carbon-based CVD gas is sucked from the other side (for example, the front side or the outside) of the radiation shield, and The internal structure was filled with carbon and then the vacuum was stopped. The densification treatment of the base material is repeated twice by such CVI treatment,
A substrate having a bulk density of 1.6 g / cm ³ was finished. The surface of the substrate thus CVI-treated is 100
A dense carbon layer with a thickness of μm is formed, and 50
A triple-layered radiation shield was manufactured by forming a μm thick SiC film by CVD.

In a similar manner, inner diameter 800 mm, height 1
50mm, 7mm thick cylindrical C / C substrate and inner diameter 8
Using a doughnut-shaped C / C substrate having a size of 00 mm, an outer shape of 1000 mm and a thickness of 7 mm, a heat retaining cylinder and a heat retaining plate having a triple structure were produced.

The radiation shield, the heat insulating cylinder, and the heat insulating plate thus produced were placed at predetermined positions in the hot zone of the silicon single crystal pulling apparatus. 250 kg of a silicon polycrystal raw material was put into a quartz crucible, heated and melted, and a single crystal having a diameter of 300 mm was pulled up by a predetermined work to manufacture it, and then the furnace was cooled to finish the process.

Even when the above steps were repeated 30 times, the radiation shield, the heat insulating cylinder and the heat insulating plate were not deformed or cracked or peeled off, and the initial state was maintained.

Comparative Example A SiC coating was formed on a conventional carbon base material to manufacture a radiation shield, a heat insulating cylinder, and a heat insulating plate having the same shapes as those of the above-described embodiments. When these were used to manufacture a silicon single crystal in the same process as in the above-mentioned example, cracks were formed in the tapered portion of the radiation shield in the first use. At the 5th time of repeated use, cracks progressed and some of them peeled off to make reuse impossible. The same is used for the heat insulation cylinder 5
At the second time, peeling and detachment occurred and it became impossible to reuse. Regarding the heat insulating plate, it deformed and curved after the first use, making it difficult to level out. The more you use it, the bigger the bow becomes,
A crack was formed on the fifth use. At this time, peeling and separation did not occur, but after that, internal silicification progressed through the cracks, and it became worn out at the 7th use,
Detachment occurred and it became impossible to reuse.

The invention is not limited to the embodiments described above. For example, although the silicon single crystal pulling apparatus has been described in the above embodiment, the present invention can be applied to a semiconductor processing member.

[0028]

According to the present invention, the thermal stress is eliminated by the special internal structure. Therefore, the semiconductor manufacturing member according to the present invention has excellent thermal shock resistance, high mechanical strength,
It becomes chemically stable, is optimal as a hot zone member, has higher quality than conventional products, and has a dramatically extended service life. Further, since the semiconductor manufacturing member according to the present invention can be made lightweight, it is excellent in workability and safety.

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) C30B 15/14 C04B 35/80 B

Claims (4)

[Claims] 1. A member for semiconductor production in which a SiC coating layer is formed on a carbon fiber reinforced carbon composite base material, wherein the composite base material is CVI-treated and filled with carbon. A member for semiconductor production, wherein a carbon coating layer formed by a CVD process is interposed as an intermediate layer between the SiC coating layer and the SiC coating layer. 2. The semiconductor manufacturing member according to claim 1, wherein the carbon coating layer is thicker than the SiC coating layer. 3. The carbon coating layer has a thickness of 100 to 200 μm.
The semiconductor manufacturing member according to claim 1 or 2, wherein 4. The bulk density of the CVI-treated composite substrate is
2. The amount is 1.6 g / cm ³ or more.
The member for semiconductor production as described in any one of Claims 1-3.