JPH0543271A - Production of oxynitride glass - Google Patents

Abstract

PURPOSE:To produce the high-purity oxynitride glass which is high in high-temp. viscosity, has excellent heat resistance and is free from bubbles at its m.p. or below by mixing fine silica powder and fine silicon nitride powder, molding the mixture and sintering the mixture at and under a high temp. and high pressure of specific conditions. CONSTITUTION:The fine silica powder and the fine silicon nitride powder are mixed. The mixing weight ratio of the fine silicon nitride powder and the fine silica powder is preferably set at 1:79 to 1:12 by taking the workability, mechanical characteristics, thermal characteristics, and chemical characteristics of the glass into consideration. Such fine powder mixture is molded. This molding is preferably made into the bubble-free molding by using a filter molding method of dispersing the fine powder mixture into a solvent, such as pure water, to prepare a slurry, then filtering and molding the mixture as the molding method for the above-mentioned molding. The molding is sintered at a high temp. and high pressure of >=1700 deg.C and >=200kgf/cm<2>. The atmosphere for the sintering is preferably formed of gaseous nitrogen to suppress the cracking of the silicon nitride. The sintering method is preferably a hot isostatic pressurization method using a gaseous pressure in order to suppress the bubbling in the glass.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a method for producing oxynitride glass. Especially after mixing silica fine powder and silicon nitride fine powder, molding and
The present invention relates to a method for obtaining a desired oxynitride glass by sintering at a high temperature and high pressure of 200 kgf / cm ² or more.

[0002]

2. Description of the Related Art In the field of semiconductor industry, there is a demand for a high-purity heat-resistant material that does not emit impurities due to heat and does not deteriorate at a use temperature in a heat treatment step such as doping a semiconductor. For this reason, currently fused silica glass obtained by melting quartz powder is used, but impurities such as metals contained in the raw materials are mixed in the glass even after the refining process and diffused during the heat treatment. May be released as Further, a synthetic quartz glass having a high purity can be obtained, but its heat resistance is inferior to that of fused quartz glass due to the influence of hydroxyl groups and the like mixed during the synthesis. Like this,
Satisfaction in terms of heat resistance has not been achieved with the current silica glass.

Oxynitride glass is mentioned as a glass having the properties on both sides. Oxynitride glass in which part of oxygen in oxide glass is replaced by nitrogen is already known to have improved mechanical properties, chemical properties, and thermal properties, and research has recently been actively conducted. .

[0004]

Among the methods for producing oxynitride glass reported in the past, there is a method of blowing ammonia gas into a glass melt or melting silicon nitride and a glass raw material. However, in order to obtain a high-purity oxynitride glass, when the glass raw material is silica glass, it is necessary to raise the temperature to a very high temperature, which poses a problem in industrialization. Further, treatment of ammonia gas with a dry gel body obtained by the sol-gel method using Vycor glass has been reported, but there is a problem of foaming.

According to the present invention, silica fine powder and silicon nitride fine powder are mixed and then molded, and the mixture is molded at 1700 ° C. or higher and 20
By sintering at a high temperature and high pressure of 0 kgf / cm ² or more, it is an object to obtain a highly pure and bubble-free oxynitride glass having a melting point or lower.

[0006]

The present inventors have arrived at the present invention as a result of intensive studies to solve the above problems. That is, the present invention is characterized in that silica fine powder and silicon nitride fine powder are mixed and then molded and sintered at a temperature of 1700 ° C. or higher and at a high temperature and high pressure of 200 kgf / cm ² , which is a highly pure and bubble-free oxynite. It is a method of manufacturing a ride glass. Hereinafter, the present invention will be described in more detail.

In the method for producing silica glass of the present invention, the starting material is a fine powder of a mixture of silica and silicon nitride. The silica fine powder may be produced by any method such as the soot method and the sol-gel method. However, in order to uniformly mix the silicon nitride powder and the silica powder, the particle diameter is preferably 30 μm or less.

The weight ratio of silicon nitride and silica fine powder to be mixed is 1:79 or more and 1:12 or less in consideration of the workability, mechanical properties, thermal properties and chemical properties of silica glass. Is preferred. The method of mixing with the silicon nitride fine powder may be either a wet method or a dry method.

As a method of molding the obtained raw material fine powder,
A wet molding method such as cast molding and a dry molding method such as press molding can be used, but any method may be used. However, it is preferable to use a filtration molding method that is easily bubble-free during sintering. For example, silica powder and silicon nitride mixed fine powder are dispersed in a solvent such as pure water to form a slurry,
Filter molding is recommended.

The molded body is vitrified in an oxygen-free atmosphere of 1700 ° C. or higher and at a high temperature and high pressure of 200 kgf / cm ² or more. The atmosphere is an oxygen-free atmosphere in order to suppress decomposition of silicon nitride. . Further, in order to enhance the effect, it is preferable to use nitrogen gas as the atmosphere. The sintering method may be any method such as uniaxial press sintering by hot pressing method, but in order to suppress decomposition of silicon nitride and foaming in the glass, sintering by hot isostatic pressing method using gas pressure is preferable.

[0011]

EXAMPLES In order to explain the present invention in detail, the following examples are given, but the present invention is not limited thereto.

Example 1 A silica fine powder obtained by flame hydrolysis using silicon tetrachloride as a raw material was used as a raw material. Using an agate ball and pot, silicon nitride and finely powdered silica fine powder were mixed and pulverized in a weight ratio of 1:79 for 24 hours using an agate ball mill with pure water as a dispersion medium. After drying the obtained slurry of the mixed fine powder, it was re-ground in an agate mortar, pressed and cold isostatically molded to obtain a molded body.

The molded body was put into a helium atmosphere at 1400 ° C. and baked, and thereafter, the molded body was subjected to
Transparent vitrification was performed at 750 ° C. in a nitrogen atmosphere of 1000 kgf / cm ² .

(Example 2) Using a silica fine powder produced by the same method as in Example 1 as a raw material, silicon nitride and fine powder silica fine powder were mixed at a weight ratio of 1:36 with pure water as a dispersion medium, and an agate ball mill was used. Was mixed and ground for 24 hours. After drying the obtained mixed fine powder slurry, it was re-ground in an agate mortar, and the mixed powder and pure water were mixed at a weight ratio of 10: 1 to form a slurry, which was filtered by a suction filtration method. Filtration is performed until there is no water on the surface,
After drying, a molded body was obtained by cold isostatic molding.

The molded body was put into a helium atmosphere at 1400 ° C. and baked, and then the molded body was hot-isostatically pressed to
Transparent vitrification was performed at 750 ° C. in a nitrogen atmosphere of 1000 kgf / cm ² .

(Comparative Example) The silica fine powder used in the examples was press-molded by using a mold and transparent vitrified at 1540 ° C. in a helium gas atmosphere.

Table 1 shows the results of quantitative analysis of the nitrogen content in the oxynitride glass obtained by the above steps and the viscosity coefficient measured at 1400 ° C. by the beam bending method.

Table 1 Nitrogen concentration (wt%) Viscosity coefficient (poise) Example 1 0.5 6.62 × 10 ¹⁰ Example 2 1.0 1.18 × 10 ¹¹ Comparative Example 0 9.28 × 10 ⁹ Table As is clear from the above, by introducing nitrogen into the glass, a bubble-free glass having an excellent viscosity coefficient, that is, excellent heat resistance was obtained.

[0019]

INDUSTRIAL APPLICABILITY As described above, a bubble-free and high-purity oxynitride glass having high temperature viscosity and excellent heat resistance can be prepared at a melting point or lower.

Claims (5)

[Claims] 1. In a method for producing oxynitride glass, silica fine powder and silicon nitride fine powder are mixed and then molded and molded at 1700 ° C. or higher and 200 kgf / cm ^2.
A method for producing an oxynitride glass, which comprises sintering at the above high temperature and high pressure. 2. The method for producing an oxynitride glass according to claim 1, wherein the mixing weight ratio of the silicon nitride fine powder and the silica fine powder is 1:79 or more and 1:12.
A manufacturing method characterized by the following. 3. The method for producing an oxynitride glass according to claim 1 or 2, wherein the mixed fine powder of silica and silicon nitride is dispersed in a solvent to form a slurry, which is then molded by filtration. A manufacturing method characterized by: 4. The method for producing an oxynitride glass according to any one of claims 1 to 3, wherein the atmosphere of the high temperature and high pressure treatment is nitrogen gas. .. 5. The method for producing an oxynitride glass according to any one of claims 1 to 4, wherein the high temperature and high pressure treatment is performed by a hot isostatic method. Method.