JPH09208236A - Production of carbon-containing quartz glass - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing the carbon-contg. quartz glass capable of being appropriately used for the vessel, jig, etc., for heat-treating a semiconductor wafer or a substrate, etc., for a surface heater, excellent in mechanical, thermal, electrical and IR radiating characteristics and excellent in oxidation resistance. SOLUTION: The partial polycondensation product of a silicon alkoxide is hydrolyzed with a basic catalyst in the presence of a solvent, org. polymer and salt to prepare a sol, the sol is gelled, and the dried gel is heated in an oxygen-free atmosphere and vitrified to incorporate carbon into the glass. Otherwise, the dry gel prepared by this method is fired to form a porous glass, the porous glass is impregnated with a resin soln., dried and then heated and vitrified in an oxygen-free atmosphere to to obtain a carbon-contg. glass. Consequently, a large-sized carbon-contg. quartz glass having a high content of carbon and applicable in various uses is easily produced.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a method for producing carbon-containing quartz glass.

[0002]

2. Description of the Related Art By combining silica glass and carbon, the heat resistance of silica glass is improved while maintaining the excellent characteristics of silica glass (high purity, low thermal expansion, thermal shock resistance) and oxidation resistance. It is considered that functional improvement such as (suppression of deformation at high temperature), improvement of infrared emissivity, and increase of conductivity can be realized, and some studies have been made in recent years. Less than,
I will introduce the main ones.

Ronald Howard Vanilly et al. Proposed a method for obtaining a carbon-containing glass by thermally decomposing a stable gel obtained from an organosilsesquioxane, a metal oxide and a metal alkoxide in an inert atmosphere or a vacuum. (Japanese Patent Laid-Open No. 59-97550).

Takagi et al. Have reported that by hydrolyzing a hydrolyzed solution (sol) of silicon alkoxide into a gel and drying it to adjust the content of residual organic matter in the gel, heating the mixture in an oxygen-free atmosphere to carbonize the organic matter. A method for obtaining a contained glass (porous) has been proposed (JP-A-2-23912).
No. 2).

Yamada et al. Described a method of obtaining a glass (porous) uniformly containing carbon by gelling a hydrolyzing solution of silicon alkoxide containing carbon tetrachloride, drying and firing in an oxygen-free atmosphere. (JP-A-62-123029 and JP-A-62-12303).
No. 0).

Hama et al., After reacting a porous glass body prepared by a flame hydrolysis method, a sol-gel method, a phase separation method, etc. with a silicon compound containing carbon which reacts with a hydroxyl group,
A method for obtaining a glass containing carbon by firing in an oxygen-free atmosphere has been proposed (JP-A-3-126638).

In the above-described method for producing carbon-containing quartz glass, it is difficult to increase the size of the glass, which is indispensable when the carbon-containing quartz glass is applied to a jig for semiconductor production or a substrate for a surface heater. However, there is a problem in that the carbon content in the glass cannot be increased because the carbon component (1) is obtained by carbonizing a slight residual volatile substance.

[0008]

DISCLOSURE OF THE INVENTION The present invention provides a method for producing a carbon-containing quartz glass which realizes an increase in the size of the carbon-containing glass and an increase in the carbon content in the glass.

[0009]

The present invention provides mechanical, thermal, electrical and infrared radiation characteristics which can be suitably used for containers and jigs for heat treatment of semiconductor wafers, substrates for surface heaters and the like. The present invention relates to a method for producing a carbon-containing quartz glass which is excellent and excellent in oxidation resistance. A method for producing a carbon-containing quartz glass, which comprises hydrolyzing a sol, gelling, and drying a dried gel obtained by heating in an oxygen-free atmosphere to vitrify and containing carbon in the glass. The second invention of the present application is to obtain a dried sol obtained by hydrolyzing a partially polycondensed product of a silicon alkoxide with a base catalyst in the presence of an organic polymer, a solvent and a salt to form a sol, gelling and drying. By firing the gel at a temperature of 700-1300 ℃ and porous glass, porous glass is impregnated with resin solution, dried, heated in an oxygen-free atmosphere,
A method for producing carbon-containing quartz glass, which comprises vitrifying.

The present inventors have studied a method for producing quartz glass that solves the above-mentioned problems, and as a result, hydrolyzed a partial condensation polymer of silicon alkoxide using a base catalyst in the presence of a solvent, an organic polymer and a salt. Gel the prepared sol,
By heating and vitrifying the dried gel obtained in an oxygen-free atmosphere, carbon-containing quartz glass of practically sufficient size can be easily produced, and the dried gel produced by the above method is calcined. To form porous glass, impregnate this porous glass body with a resin solution, dry it, and heat it in an oxygen-free atmosphere to vitrify it, thereby increasing the size of the glass and simultaneously increasing the carbon content in the glass. The inventors have found out what can be done and have completed the present invention.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION As a partial condensation polymer of a silicon alkoxide used in the present invention, a partial condensation polymer such as silicon tetramethoxide, silicon tetraethoxide or silicon tetrapropoxide can be used. It is preferable to use a partially condensed polymer of silicon tetramethoxide from the viewpoint that the size of the glass obtained can be easily increased.

As the solvent used in the present invention, use of a mixed solvent of alcohols such as methanol, ethanol, propanol and the like, high boiling point solvents such as dimethylformamide, dimethylacetamide, tetrahydrofurfuryl alcohol and the like will increase the size of the glass. Is preferred.

As the organic polymer used in the present invention, polyvinyl acetate, polyethylene glycol and its derivatives, hydroxypropyl cellulose and the like can be used.

The salts used in the present invention include bases such as ammonium hydroxide, tetramethylammonium hydroxide, tetraethylammonium hydroxide, tetrapropylammonium hydroxide, trimethylethylammonium hydroxide (choline) and nitric acid, hydrochloric acid and the like. Salts with acids can be used.

As the base catalyst used in the present invention, tetramethylammonium hydroxide, tetraethylammonium hydroxide, tetrapropylammonium hydroxide, trimethylethylammonium hydroxide (choline) can be used.

The sol prepared by using the above components is poured into a container, allowed to stand and gelated, and dried to prepare a dried gel. Any known method using a gas-permeable film or a method using a pinhole can be used for drying the gel.

Carbon-containing quartz glass is obtained by heating and vitrifying the produced dry gel in an oxygen-free atmosphere at a temperature of 1400-1500 ° C., for example. The oxygen-free atmosphere used is nitrogen, argon, helium,
Vacuum etc. can be used.

The dried gel is fired at a temperature of 700-1300 ° C. to obtain a porous glass body, which is impregnated with a resin solution, dried, and then heated in an oxygen-free atmosphere to vitrify. It is possible to produce carbon-containing quartz glass having a high carbon content. If the temperature at which the dried gel is made into a porous glass body is lower than 700 ° C., the strength of the porous glass body is low, and the gel is destroyed during the impregnation work with the resin solution, which is not preferable. On the other hand, if the temperature exceeds 1300 ° C, the porous body is densified and impregnation with the resin solution becomes difficult, which is not preferable. As the resin, basically any resin can be used as long as it has a large carbon content remaining after thermal decomposition, but use of a resin such as a phenol resin, an epoxy resin or a furan resin having a large residual carbon content. Is preferred. As the solvent for dissolving these resins, any solvent can be basically used as long as it can dissolve the resin. At the time of impregnation, a known method such as vacuum / pressure impregnation can be used, and the impregnation operation may be repeated a plurality of times. By firing the resin-containing porous glass body produced as described above in an oxygen-free atmosphere, quartz glass having a high carbon content can be obtained.

[0018]

【Example】

Example 1 100 parts by weight of a partially condensed polymer of silicon tetramethoxide, 500 parts by weight of methanol, dimethylformamide 3
60 parts by weight, tetrahydrofurfuryl alcohol 266
By weight, 5 parts by weight of polyvinyl acetate (degree of polymerization: 1800) were mixed. An aqueous solution of 1M choline nitrate was added to this so that the concentration of choline nitrate per 100 g of the partially condensed polymer of silicon tetramethoxide was 5.0 × 10 ⁻⁴ mol,
Then, a 1 M choline methanol solution was added so that the choline concentration per 100 g of silicon tetramethoxide partially condensed polymer would be 1.2 × 10 ⁻⁴ mol. While stirring the solution, 390 parts by weight of water was dropped, and further stirred to prepare a sol. 27 kg of the obtained sol was poured into a 1150 mm square stainless steel container coated with Teflon, and a lid having eight pin holes with a diameter of 1 mm was opened.
The sol-containing container was allowed to stand to gel, and then gradually heated from 50 ° C. to 180 ° C. to dry the gel.
The drying time was about 14 days. The obtained dried gel was heated to 1000 ° C. in a nitrogen atmosphere, the atmosphere was changed to helium, the temperature was raised to 1420 ° C., and the temperature was maintained for 1 hour to complete vitrification. Thus about 530mm square, thickness 8mm
A dense carbon-containing quartz glass having no cracks was obtained.

Example 2 A dry gel was prepared in the same manner as in Example 2. A gel of about 450 mm square was cut out from the obtained dried gel, heated to 1000 ° C. in a nitrogen atmosphere and kept for 1 hour to obtain a porous glass body. Pallet made of porous glass (about 500 m
m square) and evacuated in a vacuum desiccator, then, a novolac-type phenol resin in methanol (concentration 20)
%) Was poured into a pallet to impregnate the porous glass body with resin. The porous glass body containing the resin obtained by drying and removing the solvent is heated to 1000 ° C. in a nitrogen atmosphere,
Then, the atmosphere was changed to helium, the temperature was raised to 1450 ° C., and the temperature was maintained for 1 hour to complete the vitrification. In this way, a carbon-containing quartz glass having a size of about 220 mm square and a thickness of 8 mm without cracks was obtained.

[0020]

According to the present invention, it is possible to easily produce a large-sized carbon-containing quartz glass having a large carbon content which can be applied to various uses.

Front page continuation (72) Inventor Hiroki Terasaki 48 Wadai, Tsukuba City, Ibaraki Prefecture Hitachi Chemical Co., Ltd. Tsukuba Research Laboratory

Claims (2)

[Claims] 1. A dried gel obtained by hydrolyzing a partially polycondensed product of a silicon alkoxide with a base catalyst in the presence of an organic polymer, a solvent and a salt to form a gel, and drying the gel under an oxygen-free atmosphere. A method for producing a carbon-containing quartz glass, which comprises heating and vitrifying the glass to contain carbon in the glass. 2. A dried gel obtained by hydrolyzing a partially polycondensed product of a silicon alkoxide with a base catalyst in the presence of an organic polymer, a solvent and a salt to give a sol, gelling and drying the resulting gel is 700-1300 ° C. A method for producing a carbon-containing quartz glass, which comprises firing at a temperature of 1 to obtain a porous glass, impregnating the porous glass with a resin solution, drying and then heating and vitrifying in an oxygen-free atmosphere.