JP3185653B2 - Material for semiconductor manufacturing equipment and method for manufacturing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a material for a semiconductor manufacturing apparatus, and more particularly, to a material for a semiconductor manufacturing apparatus using quartz glass as a base material and used for forming parts of an apparatus for manufacturing a semiconductor product, and a method for manufacturing the same. About.

[0002]

2. Description of the Related Art Quartz glass has a very high purity, and has characteristics such as little gas generation even under heating at a high temperature. It is widely used as a table, a crucible, a reaction tube and the like. However, its heat resistance is relatively low, and thermal deformation becomes severe at a temperature of 1200 ° C. or higher, and it is difficult to maintain the shape of quartz glass alone. Therefore, when processing a semiconductor product at a high temperature of 1200 ° C. or more, a material other than quartz glass is used as a material constituting the device, or another heat-resistant material part is used as a support material, and the inside of the device is used. A method such as placing a quartz glass part is used.

For example, in a step of diffusing impurities in order to impart conductivity to a Si wafer (hereinafter referred to as a diffusion step), since the temperature of the Si wafer is about 1200 to 1250 ° C., a boat for supporting the Si wafer and When quartz glass is used as a material for the tube or the like, welding of the Si wafer to the boat and the tube occurs. Therefore, in order to prevent the fusion, a heat-resistant material such as silicon carbide is used in the diffusion step.

[0004] In addition, a crucible made of quartz glass is used as a container for holding a melt of a crystal raw material when pulling a Si single crystal. However, the temperature of the melt is 1400
C. or more, the quartz glass crucible softens, and the shape of the container cannot be maintained by the quartz glass crucible alone. Therefore, the quartz glass crucible is supported by fitting a carbon crucible to the outside of the quartz glass crucible. However, at present, no suitable material other than quartz glass has been found as a single crystal pulling crucible. For example, when a crucible made of a carbon material having high heat resistance is used as a crucible for a melt, it is difficult to avoid contamination by carbon, and the purity of the pulled-up Si single crystal is also low. The life time of the obtained Si wafer was not enough.

Japanese Patent Application Laid-Open No. 7-53242 discloses a method for forming a silicon oxynitride film on the surface of quartz glass in order to improve the heat resistance of the quartz glass. That is, the publication discloses that quartz glass is placed in a mixed gas of ammonia and hydrocarbons or in an ammonia gas atmosphere in which solid carbon coexists and then subjected to a heat treatment, so that the surface of the quartz glass has a highly heat-resistant acid. It is described that a silicon nitride film is formed. It is also disclosed that a silicon nitride film is further coated on the silicon oxynitride film by a CVD method.

Further, quartz glass used in a CVD thermal process at 1200 ° C. or lower has the following problems. For example, an even higher purity Si
Step of epitaxially growing a single crystal or the like (hereinafter referred to as Si
In the epitaxy process), the area around the Si wafer is 900
Quartz glass is used for the susceptor that supports the Si wafer although the temperature is about 1 to 1200 ° C. In this case, a polysilicon film is generated in a portion other than the Si wafer, and the polysilicon generation film is separated due to a difference in thermal expansion coefficient from quartz glass during cooling in a thermal cycle. The exfoliated polysilicon adheres to the Si wafer and causes a defect. Therefore, in order to prevent the adhesion of polysilicon, in the Si epitaxy process, a carbon material obtained by coating silicon carbide having substantially the same thermal expansion coefficient as a polysilicon generation film by CVD processing is used.

[0007]

However, Japanese Patent Application Laid-Open No.
As described in Japanese Patent No. 53242, the amount of thermal deformation at 1350 ° C. of the material obtained by the above method at 1350 ° C. is about half that of a quartz glass material on which no silicon oxynitride film is formed. However, there is a problem that thermal deformation is still large and it cannot be said that it has sufficient heat resistance. In addition, since the thermal stability of silicon oxynitride or silicon nitride itself is not sufficient, there is also a problem that when used in a high-temperature region of 1200 ° C. or more, deterioration and deterioration are rapid.

Further, the material described in the above publication is liable to peel off the film due to the repetition of heating and cooling due to the difference between the thermal expansion coefficients of quartz glass, silicon oxynitride and silicon nitride. This has been an obstacle to long-term use and large size.

Also, in a carbon material susceptor coated with silicon carbide, which is used in the above-mentioned CVD thermal process at 1200 ° C. or less, when pinball is generated in the silicon carbide of the coating layer, gas is generated from the carbon material as the base material. Also, there is a problem that metal impurities are generated and contaminate the product Si wafer, and the product must be replaced.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and has the advantage of improving the heat resistance while utilizing the property that the quartz glass does not contaminate the Si wafer, and has the thermal expansion coefficient between the quartz glass and the coating film. By suppressing the peeling of the coating film due to the difference, 1200
A material for a semiconductor manufacturing apparatus which can be used as a part of an apparatus for manufacturing a semiconductor product in a high temperature region of not less than ℃, and 1200
An object of the present invention is to provide a material for a semiconductor manufacturing apparatus such as a susceptor material in a CVD thermal process at a temperature of not more than ℃ and a manufacturing method thereof.

[0011]

In order to achieve the above object, a material for a semiconductor manufacturing apparatus according to the present invention has a buffer film containing porous silicon carbide formed on a substrate made of opaque quartz glass, It is characterized in that a protective film made of dense silicon carbide is formed on the buffer film.

According to the material for a semiconductor manufacturing apparatus having the above structure, an opaque quartz glass having a surface having irregularities, being porous, and having many pores near the surface is used as a base material.
Since the material containing silicon carbide that constitutes the buffer film has penetrated into the irregularities (open pores) and closed pores, the heat resistance can be improved, and the buffer film can be separated by the anchor effect. Can be prevented. Further, a protective film is formed on the buffer film, and the protective film enters the inside of the buffer film, and the peeling of the protective film is prevented by the anchor effect. Also,
Since the protective film is made of silicon carbide, which is dense and has excellent heat resistance and high mechanical strength at high temperatures, the heat resistance and mechanical strength at high temperatures of the material for semiconductor manufacturing equipment can be improved. Therefore, it should be used as a material for equipment for manufacturing semiconductor products in a high-temperature region of 1200 ° C. or higher, which has been difficult to use with quartz glass alone, and as a material for semiconductor manufacturing equipment such as a susceptor material in a CVD thermal process at 1200 ° C. or lower. Can be.

Further, a method of manufacturing a material for a semiconductor manufacturing apparatus according to the present invention uses a reactive gas containing silicon and carbon,
An opaque quartz glass is subjected to a chemical vapor deposition (CVD) process at a temperature of more than 900 ° C. and less than 1150 ° C. to form a buffer film on the surface thereof, and thereafter, a reactive gas containing silicon and carbon is used at 1200 ° C. or more. At this temperature, the opaque quartz glass having the buffer film formed thereon is subjected to a CVD process to form a dense protective film made of silicon carbide.

According to the method of manufacturing a material for a semiconductor manufacturing apparatus, opaque quartz glass having irregularities, being porous, and having many pores near its surface can be used at a low temperature of less than 1150 ° C.
Since the VD process is performed, thermal deformation of the opaque quartz glass during the CVD process can be prevented, and a porous buffer film can be formed. Further, by the above-mentioned CVD process, the material constituting the buffer film can be introduced into the irregularities (open pores) and the closed pores of the opaque glass, thereby improving the heat resistance of the opaque quartz glass. And the anchor effect prevents the buffer film from peeling off. Further, since a protective film made of silicon carbide is formed on the buffer film at a high temperature of 1200 ° C. or more, a dense protective film having excellent heat resistance and high mechanical strength at high temperatures can be formed. Further, in order to form the protective film on the porous buffer film, it is possible to prevent the material constituting the protective film from entering the inside of the buffer film and prevent the protective film from peeling off by its anchor effect. it can. Therefore, by the above manufacturing method, the heat resistance and the mechanical strength at high temperature of the material for semiconductor manufacturing equipment can be improved, and the semiconductor product can be used in a high temperature region of 1200 ° C. or higher, which has conventionally been difficult to use with quartz glass alone. Equipment material to be manufactured and CV of 1200 ° C or less
It can be used as a material for semiconductor manufacturing equipment such as a susceptor material in the D heat process.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of a material for a semiconductor manufacturing apparatus and a method for manufacturing the same according to the present invention will be described.

First, a method for manufacturing a material for a semiconductor manufacturing apparatus according to the embodiment will be described. An opaque quartz glass containing more pores than a transparent quartz glass is used as a base material of a material for a semiconductor manufacturing apparatus according to the present invention. Usually, this opaque quartz glass has irregularities to a depth of 0.5 to 6 mm from the surface, and 10 to 1000 mm to a depth of 6 mm from the surface.
It contains about 0.1 to 20% by volume of closed pores having a diameter of μm.
Considering that the opaque quartz glass is used as a part for a semiconductor manufacturing apparatus, it is preferable that the opaque quartz glass has a high purity equivalent to that of the transparent quartz glass. Those having a total content of 5 ppm or less are preferred.

The opaque quartz glass is heated to a temperature exceeding 900 ° C. in an atmosphere of a reactive gas containing silicon and carbon, and
A CVD process is performed at a temperature of less than 50 ° C. to form a buffer film containing silicon carbide on the surface of the opaque quartz glass. As the reactive gas containing silicon and carbon, for example, hydrogen, silane, and a mixed gas of methane, hydrogen, dichlorosilane,
And a mixed gas of hydrogen, trichlorosilane and methane, and a mixed gas of hydrogen, silane tetrachloride and methane. By the CVD reaction of the mixed gas, a buffer film containing silicon carbide can be deposited on the irregularities (open pores) on the surface of the opaque quartz glass, and the anchor effect prevents the buffer film from peeling off. it can. Further, since the mixed gas permeates into the closed pores, the material containing silicon carbide can be deposited to the inside of the closed pores, and the opaque quartz glass is deposited on the surface portion or deposited inside the closed pores. The vicinity of the surface can be covered with a buffer film containing silicon carbide to improve heat resistance. Further, since the temperature of the above-mentioned CVD processing is as low as less than 1150 ° C., the opaque quartz glass is not deformed by heat during the CVD processing. 900 ℃ temperature during CVD process
In the following, silicon carbide hardly precipitates. On the other hand, when the temperature during the CVD treatment exceeds 1150 ° C., the opaque quartz glass as the base material is deformed by heat.

The density of the buffer film made of silicon carbide is 2.8.
g / cm ³ or more and less than 3.1 g / cm ³ , which is porous and porous. Therefore, when a protective film is formed thereon, the material constituting the protective film enters the inside of the buffer film, and due to its anchor effect, The peeling of the protective film can be prevented.

Since the next CVD process is performed at 1200 ° C. or higher, one of the objects of forming the buffer film is to provide heat resistance so that the opaque quartz glass is not thermally deformed during the CVD process. In view of the above, the thickness of the buffer film is preferably 5 μm or more, but the thickness is 200 μm.
Above this, cracks occur in the buffer film, so the thickness of the buffer film is preferably 200 μm or less.

When the CVD process is performed, if ammonia is further added to the mixed gas, silicon nitride is precipitated together with the silicon carbide, and the buffer film containing the both can be formed. Since silicon nitride has a smaller coefficient of thermal expansion than silicon carbide, the coefficient of thermal expansion of the buffer film can be made smaller than that of silicon carbide alone, and can be close to the coefficient of thermal expansion of quartz glass. Can be more effectively prevented. Similarly, silicon oxide (SiO 2)
A buffer film containing ₂ ) can also be formed. In this case, the opaque quartz glass is made of a fluorine-based gas such as F.
_What is necessary is just to heat-process with ₂ gas and to convert a surface layer into a silica gel.
As described above, by adding a gas containing an element other than carbon and hydrogen, buffer films having various compositions can be formed, whereby the coefficient of thermal expansion of the buffer film can be adjusted.

Further, when the buffer film is formed, the composition of the mixed gas, the temperature of the CVD process, and the like are changed with time.
The material of the buffer film may be gradually changed in the thickness direction. That is, a buffer film made of a material having a small thermal expansion coefficient is formed on the side close to the opaque quartz glass to reduce the difference in the thermal expansion coefficient from the quartz glass, while the thermal expansion coefficient gradually increases as approaching the protective film. By changing the material of the protective film and reducing the difference in thermal expansion coefficient between the protective film and the silicon carbide constituting the protective film, the protective film can be prevented from peeling off.

After the buffer film is formed by the above method, the opaque quartz glass on which the buffer film is formed is subjected to a CVD process at a temperature of 1200 ° C. or more using a reactive gas containing silicon and carbon. A protective film made of dense silicon carbide is formed on the film. Examples of the reactive gas containing silicon and carbon include a mixed gas of hydrogen, silane, and methane, a mixed gas of hydrogen, dichlorosilane, and methane, a mixed gas of hydrogen, trichlorosilane, and methane, hydrogen, silane tetrachloride, and methane. And the like. In order to form the protective film made of dense silicon carbide, the temperature of the CVD treatment is preferably 1200 ° C. or higher. However, considering the heat resistance of the opaque quartz glass and the crystallinity and density of the silicon carbide to be formed, it is 1250 to 150 ° C. 1350 ° C. is more preferred. The formed protective film is dense and has good crystallinity, and thus has excellent heat resistance and high mechanical strength at a high temperature of 1200 ° C. or higher.

This protective film needs to have a sufficient thickness so that the material for semiconductor manufacturing equipment can be repeatedly used at a temperature higher than 1200 ° C. for a long time, and the thickness is 50 μm from the above viewpoint. More preferably,
100 μm or more is more preferable. The density is 3.
About 1 to 3.2 is preferable.

The material for a semiconductor manufacturing apparatus obtained by the above manufacturing method has a three-layer structure, in which the buffer film is formed on the opaque quartz glass, and the protective film is formed on the buffer film. I have.

As described above, the buffer film and the protective film are less likely to be peeled off than the opaque quartz glass and the buffer film present below, and the opaque quartz glass is coated with these heat-resistant films. Excellent in properties and mechanical strength. Therefore, the material for a semiconductor manufacturing apparatus according to the present invention has significantly improved heat resistance as compared with the case of using opaque quartz glass alone, and no peeling or the like occurs even when used at a high temperature of 1200 ° C. or more. It can be used as a susceptor used in the Si epitaxy process, a high-temperature reaction tube, a crucible for pulling a single crystal, etc., as a part of a semiconductor manufacturing apparatus used at 1200 ° C. or higher. The material for a semiconductor manufacturing apparatus according to the present invention has a metal impurity concentration of 30 pp.
Since a coating film having a high purity of b or less is formed, when a semiconductor product is manufactured using this material for a semiconductor manufacturing apparatus, the semiconductor product is not substantially contaminated.

Even if a pinhole is formed in the coating film of the protective film and the buffer film and the pinhole penetrates to the quartz glass of the base material, the base material is not a carbon material but a quartz glass. Unlike a raw material, a semiconductor product is not substantially contaminated by generation of gas or generation of metal impurities.

[0027]

EXAMPLES AND COMPARATIVE EXAMPLES Hereinafter, examples of materials for a semiconductor manufacturing apparatus and a method of manufacturing the same according to the present invention will be described.

Example 1 and Comparative Examples 1 to 3 Disc-shaped opaque quartz glass having a diameter of 100 mm and a thickness of 5 mm was used as a substrate in Example 1. A transparent quartz glass having the same shape was used.

These substrates are placed on a needle-shaped support member made of silicon carbide or the like which is disposed at the apex of an equilateral triangle having a side of 6 cm, and placed in a thermal CVD apparatus. 1 liter / min of silane gas, 2 methane gas
The substrate was subjected to a CVD treatment at 1050 ° C. for 1 hour at a flow rate of 50 liters / minute and hydrogen at 50 liters / minute. By the CVD process, a thickness of 1
A 0 μm silicon carbide film was formed. In addition, the measurement of the film thickness, and observation of the structure of the film, etc. are performed by measuring the following amount of deflection, cutting the substrate in a direction perpendicular to the surface, and observing the cross section with a microscope. Was.

From the above microscopic observation, it was confirmed that the formed silicon carbide film had many pores in each case. Further, in the case of Example 1, a silicon carbide film (buffer film) is formed inside the uneven portion on the surface of the base material, the open pores and the closed pores near the surface, and the separation between the buffer film and the base material is performed. Was not observed. On the other hand, in the case of Comparative Example 1, cracks and peeling from the substrate were observed in the formed silicon carbide film. In the case of Example 1, the amount of deflection in the radial direction of the opaque quartz glass subjected to the CVD treatment was 12 μm.
Was small.

Next, the same heat C as in the case of forming the buffer film is used.
The material according to Example 1 in which the buffer film was formed on opaque quartz glass using a VD device and a gas having the same composition,
CVD treatment was performed at 1250 ° C. for 3 hours to form a silicon carbide film (protective film). Further, as a material according to Comparative Example 2, opaque quartz glass having no buffer film formed by the CVD process was used, and a silicon carbide film was formed under the same conditions.

After that, as in the case where the buffer film was formed, the thickness and structure of the silicon carbide film were observed.
Its thickness was 120 μm, and it was found that it had no pores. In the case of Example 1, no peeling was observed in the formed protective film or the buffer film existing under the protective film, but in the material according to Comparative Example 2, cracks and peeling were observed in the formed silicon carbide film. Was done. The amount of deflection in the radial direction of the material for a semiconductor manufacturing apparatus according to Example 1 generated during the CVD process was extremely small at 12 μm, whereas the amount of deflection of the material according to Comparative Example 2 having no buffer film was 70 μm.
It has become as large as 0 μm.

Next, as Comparative Example 3, opaque quartz glass (same as Comparative Example 2) on which a protective film was not formed by CVD treatment was adopted, and the material according to Comparative Example 2 and the semiconductor manufacturing apparatus according to Example 1 were used. The material is put into the thermal CVD apparatus and the CV
D treatment is not performed, but simply at 1300 ° C in an argon atmosphere.
Heated for hours. As a result, the deflection amount in the radial direction of the material for a semiconductor manufacturing apparatus according to Example 1 was as small as 20 μm, whereas the deflection amount of the material according to Comparative Example 2 was 20 mm.
It was an extremely large value.

Example 2 Example 1 was repeated except that when forming a buffer film on opaque quartz glass, ammonia gas was flowed at a flow rate of 1/4 of methane gas in addition to trichlorosilane gas, methane gas and hydrogen. A material for a semiconductor manufacturing apparatus was manufactured under the same conditions as in the above case. The thickness of the formed buffer film was 12 μm, and the thickness of the protective film was 125 μm. In the buffer film, silicon nitride is deposited in addition to porous silicon carbide, no pores are observed in silicon carbide constituting the protective film, and no peeling or crack is observed in the buffer film and the protective film. Was. The deflection amount of the manufactured material for a semiconductor manufacturing apparatus was 10 μm or less.

Next, the material for a semiconductor manufacturing apparatus is converted into the heat CV
When placed in a D apparatus and heated at 1300 ° C. for 2 hours in an argon atmosphere, the amount of deflection was 15 μm.

[Examples 3 to 8 and Comparative Examples 4 and 5] The CVD process at the time of forming the buffer film was performed at 900 ° C. (Comparative Example 4) at 95 ° C.
0 ° C. (Example 3), 1000 ° C. (Example 4), 1100
° C (Example 5), 1130 ° C (Example 6), 1150 ° C
A buffer film and a protective film were formed under the same conditions as in Example 1 except that the thickness was changed to (Comparative Example 5). The amount of deflection when heated at 1300 ° C. for 2 hours was measured. The results are shown in Table 1 below.

[0037]

[Table 1]

As is clear from the results shown in Table 1, the opaque quartz glass not subjected to the CVD treatment (Comparative Example 3) had an extremely large deflection of 20 mm, whereas the temperature of the CVD treatment was 900 mm. ℃ and 115
When the temperature is lower than 0 ° C. (Examples 3 to 6), 2 ° C. at 1300 ° C.
Even when heating was performed for a long time, the amount of deflection of the manufactured material for a semiconductor manufacturing apparatus was extremely small at 50 μm or less, and the mechanical strength in a high-temperature region was significantly improved.

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-3-187954 (JP, A) JP-A-3-112131 (JP, A) JP-A 8-83835 (JP, A) (58) Investigation Field (Int.Cl. ⁷ , DB name) C03C 17/34 C30B 15/10 H01L 21/22 501 H01L 21/205

Claims (2)

(57) [Claims] 1. A buffer film containing porous silicon carbide is formed on a substrate made of opaque quartz glass, and a protective film made of dense silicon carbide is formed on the buffer film. For semiconductor manufacturing equipment. 2. An opaque quartz glass is subjected to a chemical vapor deposition (CVD) process at a temperature of more than 900 ° C. and less than 1150 ° C. using a reactive gas containing silicon and carbon to form a buffer film on the surface thereof. Then, using a reactive gas containing silicon and carbon, the opaque quartz glass on which the buffer film is formed is subjected to CVD treatment at a temperature of 1200 ° C. or more to form a protective film made of dense silicon carbide. A method for manufacturing a material for a semiconductor manufacturing apparatus.