JP2001163638A - Surface decorating quartz glass and method for manufacturing the same as well as application for the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide surface decorating quartz glass which has an excellent adhesion property and thermal impact property, exhibits high corrosion resistance particularly a plasma of a fluorine system and can maintain transparency for a long period of time even when exposed to the plasma, a method for easily manufacturing the surface decorating quartz glass and a member for a semiconductor manufacturing apparatus using the surface decorating quartz glass. SOLUTION: The surface decorating quartz glass formed by coating the surface of quartz glass with an aluminum oxide film by a sol-gel method and the method for manufacturing the same as well as the member for the semiconductor manufacturing apparatus using the surface decorating quartz glass are used.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a surface-modified quartz glass suitably used in the field of semiconductor manufacturing and a method for manufacturing the same, and further relates to a member for a semiconductor manufacturing apparatus using the surface-modified quartz glass.

[0002]

2. Description of the Related Art Conventionally, quartz glass has excellent properties such as high purity, heat resistance, chemical resistance, high permeability, and easy workability. It is used as For example, quartz glass is used as a wafer transfer / support member such as a reaction tube or a wafer boat of a heat treatment apparatus in a semiconductor manufacturing apparatus, a dry etching apparatus, an ashing apparatus (resist removal), and a plasma CVD (Chemical Vapor Depth).
It is used as a member of a bell jar, a chamber, a table, and the like of an position apparatus and a window material for internal observation.

In the dry etching apparatus and the plasma CVD apparatus, plasma is generated. Therefore, measures against plasma corrosion of quartz glass used as a member for a semiconductor manufacturing apparatus, that is, plasma resistance have become a major issue. As such, corrosion due to chemical reaction and corrosion due to ion bombardment are known.

One example of corrosion due to a chemical reaction is that caused by fluorine plasma, which dissociates in plasma to produce fluorine radicals, which react with quartz glass to form volatile Si.
Generates F ₄ and corrodes quartz glass. Dennis
W. Hess, PlasmaChemistry an
d Plasma Processing, Vol.
2, No. 2, 141-155 (1982) and Y.
H. Lee et al. Appl. Phys. Vol. 6
8, pages 5329-5336 (1990), the fluorine produced at this time reacts with aluminum to form aluminum fluoride, and the aluminum fluoride produced by the reaction between this fluorine plasma and aluminum It is well known that aluminum and alumina are resistant to fluorine plasma corrosion because they form a dense film with low volatility. Also, it is known that alumina has a small sputtering yield and is resistant to corrosion by ion bombardment.

[0005] As such a surface-modified quartz glass having excellent plasma resistance, for example, Japanese Patent Application Laid-Open No. 7-157337 discloses a method of modifying the surface of quartz glass with an aluminum oxide film by an ion plating method to improve abrasion resistance and corrosion resistance. It is proposed to improve. Furthermore, Japanese Patent Application Laid-Open No. Hei 10-139480 describes the effect of resistance to erosion by plasma-activated fluorine-based gas by similarly modifying the surface of quartz glass with an aluminum oxide film by high-frequency sputter coating. . When quartz glass is used for a member for a semiconductor manufacturing apparatus, quartz glass is susceptible to corrosion. For this reason, it has been attempted to use quartz glass surface-modified with an aluminum oxide film as described above.

However, in the case of the above-mentioned ion plating method, the aluminum oxide film (the coefficient of thermal expansion at 1000 ° C. is about 8 × 10 ⁻⁶ K ⁻¹ ) and the quartz glass (1
The coefficient of thermal expansion at 000 ° C. is about 0.5 × 10
^-6 K ^-1 ), and the internal stress in the aluminum oxide film easily causes peeling, resulting in insufficient adhesion. Further, in the coating process by high frequency sputtering, there is a problem that a film forming speed is slow, and electron beam damage is likely to occur at the time of film forming. In addition to the problems of adhesion and thermal shock of these films, both have the problem that the film forming operation is complicated and the apparatus is expensive. When quartz glass is used for a member of a semiconductor manufacturing apparatus, the shape is often a complicated shape such as a bell jar or a wafer boat. However, in these methods, it is difficult to modify the surface of the member into a concave portion or a curved surface. Was.

[0007] In addition to these, for example,
In Japanese Patent Application No. 0-5524, application of Al alkoxide,
Quartz glass whose surface has been modified with an aluminum oxide film by thermal decomposition has been reported, but this is aimed at improving the resistance to devitrification at high temperatures and has sufficient performance as a member for semiconductor manufacturing equipment. A desired quartz glass has been desired.

[0008]

SUMMARY OF THE INVENTION In view of the above-mentioned problems in the conventional method, an object of the present invention is to provide excellent adhesiveness and thermal shock resistance.
A surface-modified quartz glass that exhibits high corrosion resistance to both plasma corrosion due to chemical reaction and plasma corrosion due to ion bombardment, and can maintain transparency for a long time even when exposed to plasma, and a method for easily manufacturing this surface-modified quartz glass. To provide. It is a further object of the present invention to provide a member for a semiconductor manufacturing apparatus using this surface-modified quartz glass and utilizing plasma, particularly a member for a semiconductor manufacturing apparatus useful as a window material for internal observation.

[0009]

Means for Solving the Problems The present inventors have made intensive studies in order to solve the above-mentioned problems, and as a result, applied a coating solution composed of an alkoxide of Al on quartz glass, and then fired the alumina. By forming the coating, it is possible to obtain a surface-modified quartz glass coated with a coating containing at least aluminum oxide as a constituent element, and the coating coated with the surface-modified quartz glass has ultrafine pores. ,
In addition to being excellent in adhesiveness and thermal shock resistance, they have high corrosion resistance to plasma, and thus have been found to be able to maintain transparency for a long time even when exposed to plasma. Furthermore, by utilizing the characteristics of this surface-modified quartz glass, they have found that they are useful as members for semiconductor manufacturing equipment using plasma, particularly as window materials for internal observation, and have completed the present invention. Was.

Hereinafter, the present invention will be described in detail.

The surface-modified quartz glass of the present invention is obtained by a sol-gel method, that is, a method of applying a coating solution mainly composed of an alkoxide of Al to the surface of quartz glass and then baking to form an aluminum oxide film.
The coating obtained by this method includes BULENT E. YO
LDAS, CERAMIC BULLETIN, VO
L. 54. No. 3, 286-288 (1975)
As described in the above, there is a feature that many pores of about 100 to 150 angstroms are formed. Therefore, the density of the alumina coating on the surface-modified quartz glass of the present invention is substantially lower than that of ordinary alumina crystals.

Further, by coating quartz glass with aluminum oxide by the sol-gel method, a film having better adhesiveness than other methods can be obtained. This is because the alkoxide remaining on the quartz glass surface reacts with the alkoxide to form a strong bond. In spite of the good adhesion between the quartz glass and the coating, the ultrafine pores having a diameter of several nanometers prevent cracks from developing, so that vibrations, impacts with solids, and even heating and cooling are repeated. Even with thermal stress,
These are absorbed and the coating does not peel off.

On the other hand, as described above, plasma corrosion includes corrosion due to chemical reaction and corrosion due to ion bombardment. In the case of the surface-modified quartz glass coated with aluminum oxide of the present invention, when corrosion is caused by chemical reaction. For example, for fluorine ions, a dense film of non-volatile aluminum fluoride is formed, so that the progress of corrosion can be suppressed.In the case of corrosion by ion bombardment, aluminum oxide has a small sputtering yield, In addition to being resistant to impact, the aluminum oxide coating has many pores, and the angle of incidence of high-energy ions on the aluminum oxide surface near the pores becomes substantially shallow, so that ion impact can be reduced.

In order to improve the peeling resistance of the coating layer in the surface-modified quartz glass of the present invention, it is effective to form a coating layer of a mixed composition of silicon oxide and aluminum oxide as a base of the aluminum oxide coating. . in this case,
For example, aluminum tri-sec-butoxide (a
luminium tri-sec-butoxid
e) and tetraethoxysilane (tetraethoxysilane)
sol is made from the mixture consisting of
It suffices to apply the coating, so that stress concentration at the interface between the quartz glass and the coating layer due to the difference in thermal expansion between the quartz glass and the coating layer is reduced, and peeling of the coating film can be prevented.

[0015] In addition, a multilayer film of the same type may be laminated on the aluminum oxide film in any number of layers, or the aluminum oxide-coated quartz glass is further immersed in an aqueous solution containing aluminum fluoride to form an aluminum oxide layer. Alternatively, a multilayer surface-modified quartz glass may be formed by forming at least one coating layer having at least a component containing alumina, such as by coating an aluminum fluoride layer having a different film quality from the above.

As described above, since the surface-modified quartz glass of the present invention has resistance to plasma corrosion, the member for semiconductor manufacturing equipment particularly exposed to plasma,
It is particularly useful as a window material, a bell jar, a chamber, a tube, and a wafer support member of a semiconductor manufacturing apparatus using plasma.

As described above, the surface-modified quartz glass of the present invention is formed by applying a coating solution composed of Al alkoxide on the quartz glass surface, followed by firing to form an aluminum oxide film. Examples of the Al alkoxide used in forming the aluminum oxide film include, for example,
Al (OC ₃ H ₇ ) ₃ (aluminium isop
(ropoxide) and Al (OC ₄ H ₉ ) (alum
Indium tri-sec-butoxide) can be used, but is not limited thereto.

In the preparation of such a coating solution, the above alkoxide is preferably dissolved in a solvent such as isopropyl alcohol. Then, the required amount of water is added and polymerized,
A coating liquid is provided. Here, when an alkoxide of Al is used, the reactivity with water is high, and precipitation or inhomogeneous precipitation may occur during hydrolysis, which causes an inhomogeneous portion in the film quality or adversely affects adhesion. May have an effect. To prevent this, the addition of a chelating agent that forms a stable chelate compound by coordinating with Al ions to the alkoxide of Al can suppress the reactivity, thereby preventing precipitation during hydrolysis and heterogeneous precipitation. Can be prevented. As the chelating agent to be used, ethyl 3-oxobutanoate, acetylacetone, or the like can be used, but any known chelating agent may be used.

As an underlayer for the aluminum oxide coating layer, Al alkoxide and Si such as tetraethoxysilane are used.
A sol may be prepared based on a mixture with an alkoxide of the formula (1) and applied. As for the mixing ratio of the alkoxide of Al and the alkoxide of Si, various coating ratios are prepared and coated a number of times to form a coating in which the ratio of aluminum oxide to silicon dioxide is substantially continuously changed. Can be.

As a method of applying such a coating solution to the surface of the quartz glass, various coating methods may be used as long as the method can uniformly apply the coating solution. For example, a dipping method, a spin coating method, a spray method, a printing method, a method combining these, or a known coating means can be appropriately used.

Since the surface-modified quartz glass of the present invention can be applied in various ways as described above, it can be applied to a quartz glass structure or a large-sized member having a complicated shape having a curved surface or an uneven surface. .

After the coating solution, which is a sol formed by hydrolysis and polymerization of the metal alkoxide, is applied,
Quartz glass is fired at a temperature in the range of 350-1400C. Here, if the firing temperature is lower than 350 ° C., the firing after gelation becomes insufficient, and the transparency of the coating and the adhesion to the quartz glass may be weak. If the firing temperature exceeds 1400 ° C., the reaction between the coating and the quartz glass may occur. The range of 350 to 1400 ° C. is preferable because the quality of the coating and the deformation of the quartz glass are easily caused.

The thickness of the coating layer can be adjusted to a desired value by adjusting the metal alkoxide concentration of the coating solution and repeating coating and baking a number of times. For example, by reducing or increasing the concentration of the metal alkoxide, it is easy to apply 10 nm to 5 μm
Can be formed. In addition, if coating and firing are performed a number of times, it is easy to form a coating having a thickness of 100 μm or more.

Although high transparency is required for an observation window material for a semiconductor manufacturing apparatus using a plasma, the coating of the surface-modified quartz glass of the present invention has a very small size despite having pores. Because it is fine, the translucency of the coating itself,
When the light transmittance is measured by irradiating the quartz glass with light having a wavelength of 500 nm, the light can be as high as 80% or more when the thickness of the quartz glass is 10 mm or more, and the transparency is maintained for a long time even when exposed to plasma. Because of its excellent transparency, it is highly useful as a transparent material. On the other hand, quartz glass such as an inlet tube and a bell jar may be made of opaque quartz glass or a translucent material with a changed surface roughness in order to equalize or block heat, and may be appropriately selected depending on the use of the member.

As described above, the surface-modified quartz glass coated with the alumina coating of the present invention can be obtained by applying and baking a coating solution containing an Al alkoxide, and has particularly high resistance to plasma corrosion. Window material, bell jar, for semiconductor manufacturing equipment utilizing plasma
Suitable for chambers, tubes, wafer support members.

[0026]

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited thereto.

Example 1 First, 13 cc of aluminum tri-sec-butoxide was added to 75 cc of isopropyl alcohol, and the mixture was stirred for 1 hour. Ethyl 3-oxobutanoate (eth
yl acetoacetate) Add 13cc and add 3
Stirred for hours. Add isopropyl alcohol 20
A solution prepared by adding 3 cc of pure water to cc and stirring was gently dropped and stirred and mixed, and further stirred for 1 hour to prepare a solution composed of alkoxide. A polished quartz glass disk of φ30 mm × 10 mm was immersed in this solution, pulled up at a speed of 15 cm / min, and dried for 12 hours. This is put in a quartz container, and 90
The temperature was raised to 0 ° C. in 5 hours, heated at 900 ° C. for 1 hour, and then cooled in a furnace, and a quartz glass disk was coated with an aluminum oxide film. The thickness of the coating is about 2 μm, 500
The visible light transmittance in nm was 91%.

The quartz glass disk coated with the aluminum oxide film was exposed to plasma for 2 hours using a plasma etching apparatus. RF power is 50 W, CF ₄ gas is 100 cc / min, and O ₂ gas is 10 cc / min.
Shed in minutes.

After exposing the plasma, the quartz glass disk was visually observed. The opposite side was clearly visible and had sufficient transparency. The thickness of the film was about 2 μm, there was almost no decrease in the film thickness, and the etching was slight. The visible light transmittance at 500 nm was 83%.

Example 2 First, 9 cc of aluminum tri-sec-butoxide and 8 cc of tetraethoxysilane were added to 85 cc of isopropyl alcohol and stirred for 1 hour. This is 3
13 cc of ethyl oxobutanoate was added and the mixture was stirred for 3 hours. A solution obtained by adding 3 cc of pure water to 20 cc of isopropyl alcohol was stirred and mixed gently while dropping, and further stirred for 1 hour to prepare a solution composed of alkoxide. Add a polished φ3 to this solution.
After a 0 mm × 10 mm quartz glass disk was immersed, it was pulled up at a speed of 15 cm / min and dried for 12 hours. This was placed in a quartz container, heated in an electric furnace to 900 ° C. in 5 hours, heated at 900 ° C. for 1 hour, and then cooled in a furnace, and the mixed composition of aluminum oxide and silicon dioxide was placed on a quartz glass disk. The coating was coated. Next, this quartz glass disk was coated with an aluminum oxide film in the same manner as in Example 1. The thickness of the coating is about 4 μm, 500
The visible light transmittance in nm was 90%.

After exposing the quartz glass disk to plasma in the same manner as in Example 1, when the quartz glass disk was visually observed, the condition on the opposite side was clearly seen and had sufficient transparency. . The thickness of the coating is about 4 μm
The film thickness was hardly reduced, and the etching was slight. The visible light transmittance at 500 nm is 86%.
It was found that light transmittance by plasma was further reduced by inserting a coating layer having a mixed composition of aluminum tri-sec-butoxide and tetraethoxysilane between the aluminum oxide coating and quartz glass.

Comparative Example A polished and finished quartz glass disk of φ30 mm × 10 mm was exposed to plasma under the same conditions as in the example. Thereafter, when the quartz glass disk was observed, the surface exposed to the plasma was clouded and opaque. 500nm
Had a visible light transmittance of 45%. When the thickness of the quartz glass disk was measured with a micrometer, a decrease of about 5 μm was observed, and the etching rate was estimated to be about 400 Å / min.

[0033]

The surface-modified quartz glass coated with the alumina coating of the present invention is produced by applying and baking an Al alkoxide by a sol-gel method. Since the coating has ultrafine pores, it has excellent adhesion. Also has excellent thermal shock resistance. Particularly, fluorine plasma exhibits high corrosion resistance to both plasma corrosion due to a chemical reaction and plasma corrosion due to ion bombardment, and maintains transparency for a long time even when exposed to plasma. Therefore, when used as a member for a semiconductor manufacturing apparatus using plasma, particularly, as a window material for internal observation, the continuous use period of the manufacturing apparatus is extended,
It is industrially useful, for example, the maintenance is significantly improved.

Claims (10)

[Claims] 1. A surface-modified quartz glass in which an aluminum oxide film is coated on a quartz glass surface by a sol-gel method. 2. The surface-modified quartz glass according to claim 1, wherein a layer having a mixed composition of silicon dioxide and aluminum oxide is interposed between the aluminum oxide film and the quartz glass surface. 3. The surface-modified quartz glass according to claim 2, wherein in the layer having a mixed composition of silicon dioxide and aluminum oxide, the mixed composition changes continuously. 4. The surface-modified quartz glass according to claim 1, wherein one or more coating layers made of a component containing aluminum oxide are formed on the aluminum oxide coating. 5. The quartz glass according to claim 1, wherein when the quartz glass is irradiated with light having a wavelength of 500 nm and the light transmittance is measured, the quartz glass has a thickness of 10 mm or more and 80% or more. 4. The surface-modified quartz glass according to item 1. 6. The surface-modified quartz according to claim 1, wherein a coating solution containing an Al alkoxide is applied to the surface of the quartz glass, and then baked to form an aluminum oxide film. Glass manufacturing method. 7. The surface-modified quartz glass according to claim 6, wherein the coating solution is a coating solution prepared by preparing a sol based on a mixture mainly composed of an alkoxide of Al and an alkoxide of Si. Production method. 8. The method for producing surface-modified quartz glass according to claim 6, wherein the coating solution also contains a chelating agent. 9. A member for a semiconductor manufacturing apparatus, wherein:
A member for a semiconductor manufacturing apparatus, which is formed from the surface-modified quartz glass according to any one of claims 1 to 5. 10. The semiconductor manufacturing apparatus according to claim 9, wherein the member for a semiconductor manufacturing apparatus is a window material, a bell jar, a chamber, a tube, or a wafer supporting member for a semiconductor manufacturing apparatus using plasma. Element.