JP2002274948A - Silicon-silicon carbide composite member for heat treatment of semiconductor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a silicon-silicon carbide composite member which has high strength, excellent corrosion resistance, durability and thermal shock resistance, which suppresses generation of warpage or fracture and which is preferably used for a heat treatment of semiconductors such as dummy wafers. SOLUTION: The silicon-silicon carbide composite member for the heat treatment of semiconductors consists of silicon by >=45 wt.% and <=75 wt.% and silicon carbide by >=25 wt.% and <=55 wt.%. The silicon carbide is included in the form of aggregates of a fibrous material having <=150 μm thickness and the length of >=0.8 mm and <=3.5 mm.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a silicon-silicon carbide composite member for heat treatment of a semiconductor, and more particularly to a silicon-silicon carbide composite member for heat treatment of a semiconductor which can be suitably used for a dummy wafer or the like.

[0002]

2. Description of the Related Art Conventionally, semiconductor wafers such as silicon wafers have been subjected to various heat treatments such as film formation by a CVD method in a heat treatment furnace. These heat treatments are generally performed by placing a wafer to be processed on a mounting jig such as a wafer boat and loading it into a heated heat treatment furnace.
The temperature is further increased, and a carrier gas, a reaction gas, or the like is introduced. As a heat treatment furnace used for the heat treatment, a horizontal furnace in which a plurality of wafers to be processed are vertically arranged in a horizontal direction,
There is a vertical furnace in which a plurality of wafers to be processed are arranged in parallel in a vertical direction, and one of them is selectively used according to processing conditions.

[0003] In any of the heat treatment furnaces, a wafer boat for loading a wafer to be processed is arranged in a furnace core tube arranged inside the heater, and a plurality of dummy wafers are placed at predetermined positions of the wafer boat. Is placed. The dummy wafer controls the flow of the gas so that the introduced gas does not directly hit the wafer to be processed, and makes the thickness of the film formed on the wafer to be processed uniform. Further, the dummy wafers are controlled in heat insulation and gas flow so as to equalize the temperature in the heat treatment furnace, and to be processed by thermal shock caused by a rapid temperature change when the wafer boat is moved in and out of the heat treatment furnace. It also plays a role in protecting the wafer.

[0004] In general, various semiconductor heat treatment members such as a dummy wafer, a wafer boat, a furnace core tube and the like used in such a heat treatment furnace are made of a silicon material, a material made only of a CVD-silicon carbide material, or ,
After adding and kneading a binder to two or three kinds of silicon carbide powder raw materials having different average particle diameters, granulating, molding,
A silicon-silicon carbide composite material obtained by firing and reaction-sintering with molten silicon and having a CVD-silicon carbide film formed on the surface (silicon content: 15 to 2)
0% by weight).

On the surface of the semiconductor wafer, a CVD method is used.
In a heat treatment or the like for forming a film by a method, when forming a film on a wafer to be processed, a CVD film is also formed on the surface of various semiconductor heat treatment members such as the dummy wafer at the same time. When this process is repeated, the thickness of the CVD film formed on the surface of the member increases, and the stress generated from the difference in the thermal expansion coefficient between the member and the CVD film causes Peeling of the CVD film on the member surface occurs. The exfoliated CVD film becomes particles and scatters in the heat treatment furnace and contaminates the furnace, which causes a reduction in yield. Also, in some cases,
The member itself may be warped or damaged. Therefore, after the semiconductor heat treatment member is used for a certain period of time, the surface CVD film is removed by acid cleaning or the like, and the semiconductor heat treatment member is reused.

[0006]

However, since the conventional heat treatment member made of a silicon material is a brittle material, it has low mechanical strength and is easily broken.
It was extremely careful in handling.
Further, in the heat treatment step for forming the silicon film, it is difficult to remove only the silicon film from the surface of the member made of the silicon material by acid cleaning, and the member is consumed. Was short.

Therefore, in order to reduce the consumption of the member due to the acid cleaning, it has been considered to form a silicon carbide film on the surface of the member. However, a member made of a silicon material and a thermal expansion coefficient of the silicon carbide film are considered. Due to this difference, it was extremely difficult to form a uniform silicon carbide film without microcracks on the surface of the silicon material.

On the other hand, the silicon-silicon carbide composite material obtained from the silicon carbide powder as a raw material has
By forming the silicon carbide film, consumption of members due to acid cleaning can be reduced, and the life can be extended. However, since this silicon-silicon carbide composite material also contains silicon carbide in an amount of 80 to 85% by weight, in the heat treatment step of forming the silicon film, the difference in the coefficient of thermal expansion between the member and the silicon film causes The tendency of generation of particles due to peeling was strong.

[0009] Also, members made only of the CVD-silicon carbide material tend to have the same tendency as the silicon-silicon carbide composite material obtained using the silicon carbide powder as a raw material. Moreover,
Since the member is generally manufactured by a method in which a CVD-silicon carbide film is formed on a surface of a carbon base material or the like and then the carbon base material is burned out, thermal expansion of the carbon base material and the CVD-silicon carbide film is performed. Due to the difference in the coefficients, warpage and breakage are likely to occur, and it is difficult to obtain a large product.

Therefore, the present invention has been made to solve the above-mentioned problems, and has high strength, suppresses occurrence of warpage, breakage, and the like, and provides corrosion resistance, durability, and the like.
An object of the present invention is to provide a silicon-silicon carbide composite member having excellent thermal shock resistance and suitable for use in heat treatment of semiconductors such as dummy wafers.

[0011]

A silicon-silicon carbide composite member for semiconductor heat treatment according to the present invention comprises a semiconductor comprising 45% by weight or more and 75% by weight or less of silicon and 25% by weight or more and 55% by weight or less of silicon carbide. Silicon for heat treatment
A silicon carbide composite member, wherein the silicon carbide has a thickness of 150 μm or less, and a length of 0.8 mm or more and 3.5 mm.
It is characterized by being formed by an aggregate of the following fibrous bodies. According to the silicon-silicon carbide composite member, sufficient mechanical strength and thermal shock resistance for semiconductor heat treatment can be obtained.
Even when the silicon carbide film is formed by the method, it is possible to prevent the silicon carbide film from peeling due to a difference in thermal expansion coefficient.

The silicon-silicon carbide composite member preferably has a silicon carbide film having a thickness of 30 μm or more and 500 μm formed on the surface thereof. By forming a silicon carbide film on the surface of the silicon-silicon carbide composite member, corrosion resistance in acid washing and the like, durability, and thermal shock resistance can be improved, but in particular, the peeling of the silicon carbide film is prevented. From the viewpoint of the above, the thickness is preferably in the above range.

The silicon-silicon carbide composite member has a silicon carbide film having a thickness of 30 μm or more and 150 μm formed on its surface, and has a total thickness of 0.5 mm.
It is preferable that the dummy wafer is not less than 1 mm and not more than 1 mm.
Such a silicon-silicon carbide composite member can obtain sufficient corrosion resistance in acid cleaning or the like, and can be used as a dummy wafer in a heat treatment step of forming a silicon film on the surface of a wafer to be processed. Can be used as a dummy wafer that can withstand repeated use without peeling off the silicon cover.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail.
The silicon-silicon carbide composite member for semiconductor heat treatment according to the present invention comprises silicon in which silicon is 45% by weight or more and 75% by weight or less and silicon carbide in a proportion of 25% by weight or more and 55% by weight or less. , Thickness 150μ
m and a length of 0.8 mm or more and 3.5 mm or less. According to the silicon-silicon carbide composite member, silicon which has high strength, suppresses occurrence of warpage, breakage, and the like, has excellent corrosion resistance and durability, and can be suitably used for semiconductor heat treatment of dummy wafers and the like. A silicon carbide composite member is obtained.

As described above, the silicon-silicon carbide composite member for semiconductor heat treatment according to the present invention has a content of 45% by weight or more.
5% by weight or less of silicon and 25% by weight or more and 55% by weight
It is made of the following silicon carbide. When the content of silicon is less than 45% by weight, the content of silicon carbide, which is another component in the member, increases, so that the member is subjected to a heat treatment step of forming a silicon film on the surface of a wafer to be processed. In use, the difference in thermal expansion coefficient between the member and the silicon film becomes large, and the silicon film on the surface of the member is easily peeled off, whereby particles are easily generated. On the other hand, when the content of silicon exceeds 75% by weight, the content of silicon carbide, which is another component in the member, becomes small, so that sufficient mechanical strength and thermal shock resistance cannot be obtained. When a CVD-silicon carbide film is formed on the surface of the member, the difference in the thermal expansion coefficient between the film and the silicon carbide film becomes large, and the silicon carbide film on the surface of the member is easily peeled off. The effect of forming a silicon carbide film cannot be sufficiently obtained, and particles are easily generated.

The silicon-silicon carbide composite member for heat treatment of a semiconductor requires that the content of silicon and silicon carbide be within the above-mentioned ranges, but within a range that does not adversely affect a semiconductor such as a wafer to be processed. Inevitable impurities other than silicon, silicon and silicon carbide may be contained in the order of several percent by weight.

The silicon carbide contained in the member has a thickness of 1
It is formed of an aggregate of fibrous bodies of 50 μm or less. The thickness of fibrous silicon carbide is 150 μm
When it exceeds, it is difficult to obtain sufficient mechanical strength for use as a member for semiconductor heat treatment. This thickness is preferably 5 μm or more and 150 μm. The silicon carbide is in a preferable range from the viewpoint of industrial production as a composite material with silicon having a content of not less than 45% by weight and not more than 75% by weight, and when the thickness is less than 5 μm, it is sufficient. It is difficult to obtain impact resistance.

The silicon carbide has a length of 0.8 mm.
It is formed of an aggregate of fibrous bodies of not less than 3.5 mm. If the length is less than 0.8 mm, it is difficult to obtain sufficient mechanical strength to use as a semiconductor heat treatment member. From the viewpoint of obtaining a member with higher strength, the thickness is preferably 1.5 mm or more.
On the other hand, when the length exceeds 3.5 mm, industrial production of the member becomes difficult.

In the silicon-silicon carbide composite member according to the present invention, as described above, silicon carbide is contained as an aggregate of fibrous bodies. And the like can be obtained by manufacturing the member using cellulose fiber as a raw material.

The silicon-silicon carbide composite member preferably has a silicon carbide film having a thickness of 30 μm or more and 500 μm formed on the surface thereof. In particular, it is preferable to form a silicon carbide film on the surface of the member in order to improve corrosion resistance and durability in acid washing and the like, but from the viewpoint of obtaining sufficient corrosion resistance and the like, the thickness is 30 μm or more. Preferably, there is. On the other hand, the member is not less than 25% by weight.
By containing a fibrous silicon carbide aggregate of 5% by weight or less, a silicon carbide film can be firmly formed on the surface of the member.
If it exceeds μm, it is easy to peel off.

Further, the silicon-silicon carbide composite member for semiconductor heat treatment according to the present invention has a thickness of 30 μm.
It is preferable that the dummy wafer has a silicon carbide film having a thickness of 150 μm or more and an overall thickness of 0.5 mm to 1 mm. The thickness of the dummy wafer is preferably equal to the thickness of the wafer to be processed,
Usually, a material having a size of 0.5 mm or more and 1 mm or less is used.
Further, as described above, the thickness of the silicon carbide film on the surface of the dummy wafer is preferably 30 μm or more from the viewpoint of obtaining sufficient corrosion resistance in acid cleaning or the like. On the other hand, when the thickness of the silicon carbide film exceeds 150 μm, when the dummy wafer is used in a heat treatment step of forming a silicon film on the surface of the wafer to be processed, thermal expansion between the dummy wafer and the silicon film on which the silicon carbide film is formed The difference in the coefficients becomes large, and the silicon film on the surface of the member is easily peeled off, whereby particles are easily generated.

Next, a method of manufacturing a silicon-silicon carbide member for semiconductor heat treatment according to the present invention will be described. In general, the silicon-silicon carbide member according to the present invention has extremely high hardness and is difficult to perform a cutting process or the like. Is preferred.

In particular, the silicon-silicon carbide member for semiconductor heat treatment according to the present invention is preferably of high purity manufactured by the method described in Japanese Patent Application No. 2000-398035. That is, a cellulose fiber for papermaking pulp is formed into a predetermined shape, and is formed under a non-oxidizing atmosphere.
It is manufactured by a method of heating at 0 ° C. or more and 1500 ° C. or less to obtain a carbon porous body and then performing a silicidation treatment in an atmosphere containing a silicon element. The silicidation treatment is performed by a method of impregnating with molten silicon, a method of reacting with silicon monoxide gas, or the like in order to reduce the remaining amount of unreacted carbon.

The carbon porous body preferably has a bulk density of 0.10 g / cm ³ or more and 0.80 g / cm ³ or less. When the bulk density is less than 0.10 g / cm ³ , it becomes difficult for the carbon porous body to maintain the strength as a structure. On the other hand, the bulk density is 0.
If it exceeds 80 g / cm ³ , the residual amount of unreacted carbon increases. The bulk density is more preferably
0.70 g / cm ³ or less.

The method of forming the silicon carbide film on the surface of a substrate made of a silicon-silicon carbide composite material is not particularly limited, but is usually performed by a CVD method. For example, using a mixed gas of a halogenated organosilicon compound and hydrogen, reducing and pyrolyzing the halogenated organosilicon compound, depositing the generated silicon carbide on the substrate of the dummy wafer, and forming a thin film. No.

[0026]

EXAMPLES Hereinafter, the present invention will be described more specifically based on examples, but the present invention is not limited to the following examples. [Examples 1 to 3] A molded product made from cellulose fibers of papermaking pulp having a fiber thickness of 3 mm and a length shown in Examples 1 to 3 of Table 1 was carbonized at 1000 ° C. in a nitrogen atmosphere. Porous carbon materials having different bulk densities were obtained. The bulk density of the carbon porous body was measured by an underwater weight method (Archimedes method). Next, in the carbon porous body,
The molten silicon was impregnated at 1600 ° C. to obtain a silicon-silicon carbide composite material. Then, this silicon-silicon carbide composite material was processed into a dummy wafer substrate having a diameter of 200 mm and a thickness of 0.5 mm. About the obtained dummy wafer base material, the composition weight ratio of silicon and silicon carbide was measured by chemical analysis, and the bulk density and porosity were measured by a weight-in-water method (Archimedes method). Further, the three-point bending strength was measured. Table 1 shows the results.

[Comparative Examples 1 and 2] A carbon porous material having a different bulk density was formed using cellulose fibers of paper pulp having a fiber thickness of 3 mm and a length shown in Comparative Examples 1 and 2 in Table 1. Otherwise, in the same manner as in Example 1, a dummy wafer substrate made of a silicon-silicon carbide composite material was prepared, and various measurements were performed. Table 1 shows the results.

Comparative Example 3 60 parts by weight of silicon carbide powder having an average particle diameter of 70 μm and 40 parts by weight of silicon carbide powder having an average particle diameter of 10 μm were mixed, and 11 parts by weight of a binder was added thereto. After kneading, granulating and molding this mixture, 15
It was calcined at 50 ° C., impregnated with molten silicon at 1500 ° C., and reacted and sintered. The silicon-silicon carbide composite material obtained by the above reaction sintering method was processed into a dummy wafer substrate in the same manner as in Example 1, and various measurements were performed. Table 1 shows the results.

Comparative Example 4 A SiCl ₄ gas (1 l / min), a C ₃ H ₈ gas (1 l / min) and a H ₂ gas (50 l / m) were placed on a high-purity carbon substrate surface at 1250 ° C.
In), a CVD-silicon carbide film having a thickness of 800 μm was formed. Then, by firing this under an oxidizing atmosphere, the carbon substrate was burned out. The silicon carbide material obtained by the CVD method was processed into a dummy wafer base material in the same manner as in Example 1, and various measurements were performed. Table 1 shows the results.

[0030]

[Table 1]

With respect to the dummy wafer base material obtained in Example 1, the concentration of the impurity element contained therein was measured by a flameless atomic absorption spectrometry method using normal pressure acid extraction. Table 2 shows the results.

[0032]

[Table 2]

As shown in Table 2, the silicon-silicon carbide composite member (dummy wafer substrate) obtained in Example 1 had a low impurity element concentration and was high enough to be used as a semiconductor heat treatment member. Its purity was confirmed.

It was also confirmed that the amount of unreacted carbon remaining in the dummy wafer base materials obtained in Examples 1 to 3 was 0.20% by weight or less. By setting the amount of unreacted carbon to 0.20% by weight or less,
Since the silicon-silicon carbide composite member can have a more uniform structure, generation and deformation of cracks can be more effectively prevented.

Further, the above Examples 1 to 3 and Comparative Example 1
CV on the surface of each dummy wafer base material obtained in
Forming a silicon carbide film having a thickness of 100 μm by Method D,
A dummy wafer having a thickness of 0.7 mm was manufactured. Using these dummy wafers, a durability test was performed in a CVD process for forming a 2.5 μm polysilicon film on the surface of the wafer to be processed. In the CVD processing test, first, ten dummy wafers were placed on upper and lower portions of a wafer boat having a total length of 120 mm, 172 grooves, a pitch interval of 3.5 mm, a groove width of 1 mm, and a groove depth of 5 mm. Also,
A silicon wafer to be processed is placed between the upper and lower dummy wafers, and the wafer boat is
It was charged in the furnace. Next, SiH ₂ Cl ₂ gas (2
l / min) and H ₂ gas ( ₂₀ l / min),
A heat treatment was performed at 1000 ° C. for 60 minutes to form a 2.5 μm polysilicon film on the surface of the wafer to be processed. And
Each time the CVD process was completed once, the wafer to be processed was replaced, and the CVD process was repeated.

As a result of the durability test in the above-mentioned CVD process, the dummy wafers manufactured in Examples 1 to 3 were found to have a thickness of 20 mm.
At the first time, neither the peeling of the polysilicon film nor the deterioration of the CVD-silicon carbide film on the surface of the dummy wafer was observed. On the other hand, in the dummy wafers manufactured in Comparative Examples 1, 3, and 4, the polysilicon film was partially peeled from each dummy wafer at most up to the twelfth due to the repetition of the CVD process. Further, in Comparative Example 2, it was confirmed that microcracks were partially generated in the CVD-silicon carbide film on the surface of the dummy wafer.

[0037]

As described above, according to the present invention, a silicon-silicon carbide composite member having high purity and high strength can be provided. Furthermore, the silicon-silicon carbide composite member according to the present invention suppresses the occurrence of warpage and breakage, and is excellent in corrosion resistance, durability, and thermal shock resistance. Therefore, semiconductors such as dummy wafers, wafer boats, and furnace core tubes are used. It can be suitably used for heat treatment.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H01L 21/205 C04B 35/56 101X 101Y 35/80 C (72) Inventor Masahiro Yamaguchi Ogunimachi, Nishiokitama-gun, Yamagata Prefecture 378, Oguni-machi Oguni-machi Toshiba Ceramics Co., Ltd. Oguni Works F term (reference) 4G001 BA60 BA62 BA86 BB22 BB60 BB62 BB86 BC11 BC33 BC46 BC47 BC54 BC72 BD04 BD13 BD37 BD38 BE32 4K030 CA01 KA46 KA47 5F045 AA03 AB03 AC05 AF19 BB15

Claims (3)

[Claims] 1. A silicon-silicon carbide composite member for semiconductor heat treatment, comprising: 45 to 75% by weight of silicon and 25 to 55% by weight of silicon carbide, wherein the silicon carbide has a thickness of A silicon-silicon carbide composite member for heat treatment of a semiconductor, which is formed of an aggregate of fibrous bodies having a length of 150 μm or less and a length of 0.8 mm to 3.5 mm. 2. The silicon-silicon carbide composite member,
2. The silicon-silicon carbide composite member for semiconductor heat treatment according to claim 1, wherein a silicon carbide film having a thickness of 30 [mu] m or more and 500 [mu] m is formed on the surface. 3. The silicon-silicon carbide composite member,
The semiconductor wafer according to claim 1 or 2, wherein a silicon carbide film having a thickness of 30 µm or more and 150 µm or more is formed, and the whole thickness is a dummy wafer having a thickness of 0.5 mm or more and 1 mm or less. A silicon-silicon carbide composite member.