JPS63291824A - Production of quartz glass transmitting short wavelength laser light - Google Patents

Abstract

PURPOSE:To form a quartz glass free from thermal strain, structural defect and refractive index distribution, by using an alkyl silicate as a main raw material, preparing a sol and a gel using a specific method and sintering the resultant wet gel after drying. CONSTITUTION:A quartz glass transmitting laser light having short wavelength is produced by the following process. (1) A wet gel is prepared by hydrolyzing an alkyl silicate in the presence of a basic catalyst to obtain a solution containing dispersed fine silica particles having uniform particle diameter, mixing the solution with a solution produced by the hydrolysis of an alkyl silicate in the presence of an acidic catalyst at a specific ratio and gelatinizing the resultant sol. (2) The wet gel is dried to form a dry gel. (3) The dry gel is sintered to produce a transparent glass. The above process is carried out by using fine silica particles having uniform diameter as a raw material and gelatinizing the sol under centrifugal force.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a method for producing glass by a sol-gel method.

[Conventional technology]

Conventional methods for producing quartz glass include a melting method and a CVD method. In the sol-gel manufacturing method, silica fine particles with a somewhat broad particle size distribution are used as the raw material, and the sol is usually poured into a container and then allowed to stand still for gelation.

[Problem that the invention seeks to solve]

However, with conventional manufacturing methods, although there are some differences,
．． There are problems in that the transmittance of laser light with a short wavelength of less than 2 μm is small, and when viewed as a bulk, thermal strain distribution, refractive index distribution, etc. occur and the material is not homogeneous.

SUMMARY OF THE INVENTION The present invention aims to solve the above-mentioned problems, and its purpose is to provide a method for producing homogeneous, commercially available quartz glass using a sol-gel method.

[Means for solving problems]

The method for producing short-wavelength laser light-transmissive quartz glass of the present invention involves the production of glass by a sol-gel method using an alkyl silicate as a main raw material. A wet gel is prepared by gelling a sol prepared by mixing a solution in which silica fine particles of the same diameter are dispersed (first liquid) and a hydrolysis reaction solution of alkyl silicate using an acidic catalyst (second liquid) at a predetermined ratio. A process of drying the wet gel to produce a dry gel, and a process of sintering the dry gel to produce a transparent glass body, using silica fine particles of uniform particle size as a raw material to gel the sol. It is characterized by being carried out under centrifugal force.

[For use]

According to the present invention, since a highly pure liquid raw material can be selected as a raw material, essentially pure quartz glass can be produced as long as there is no contamination with impurities such as metal ions or foreign matter such as dust.

Further, by using silica particles of uniform particle size and further gelling under centrifugal force, it is possible to produce a wet gel in which there is no concentration distribution of silica particles and silica particles are regularly arranged. Therefore, the sintering rate becomes uniform as a bulk material, and homogeneous quartz glass without thermal distortion, structural defects, or refractive index distribution can be produced.

(Example) Distilled ethyl silicate, distilled ethanol, ultrapure water, and 29% ammonia water for commercial electronics industry filtered through a membrane filter with a pore size of 0.2 μm were mixed and stirred vigorously for 4 hours. After that, it was allowed to stand overnight in a cool dark place to grow silica particles. After concentrating this silica particle dispersion, the pH value was adjusted and stabilized, and the first liquid was purified by filtration using a membrane filter with a pore size of 10 μm. The silica fine particles in the prepared first liquid had a particle diameter of 0.24 μm and were monodisperse.

Next, the ethyl silicate purified by distillation is made into a pore size of 0.2 μm.
0,02N filtered through a membrane filter of
A second liquid was obtained by mixing with HCJ2 and stirring gently to perform a hydrolysis reaction.

After mixing the first liquid and the second liquid and filtering and purifying the mixture,
27J in a box-shaped container measuring 30x30xE30cm
2. 8 ρ was poured into each cylindrical container measuring 20 cmφ×40 cm, set in a modified centrifugal separator, and gelated while applying centrifugal force.

After gelation, the obtained wet gel was aged in a closed mortar, opened, heated from room temperature to 80°C, and then kept at this temperature for drying.
In a few days, a stable dry gel was obtained that did not crack even when left in the air. Each size is 21X21X21cm 1
It was 4 cmφxiecmH.

The dry gel obtained here was heated and sintered, and 13601C
It became a transparent glass body. Each size is 15X
It was 15×15cms 10cmφ×11.5cmH.

The results of physical property analysis of this glass body all agreed with those of commercially available quartz glass.

Moreover, no foreign matter such as air bubbles was present in the quartz glass produced in this example. Furthermore, it was found to be of extremely high quality with almost no thermal distortion or refractive index distribution.

The spectral characteristics in the ultraviolet and visible regions were also flat, and the quality was such that it could be used as a photomask substrate used in IC manufacturing and as a lens for short wavelength laser light.

〔Effect of the invention〕

The quartz glass thus produced according to the present invention is
It is expected that the capacity of ICs will further increase by using them for optical systems of steppers in semiconductor processes.

In addition, since it can be manufactured at a lower cost than other manufacturing methods, its uses are expected to expand in a wide range of fields.

that's all

Claims (1)

[Claims] (1) In the production of glass by the sol-gel method using alkyl silicate as the main raw material, a solution (hereinafter referred to as A step of preparing a wet gel by gelling a sol prepared by mixing a hydrolysis reaction solution of an alkyl silicate using an acidic catalyst (hereinafter referred to as a second solution) at a predetermined ratio; a step of drying the gel to produce a dry gel;
and short-wavelength laser light transmission, comprising the step of sintering the dry gel to produce a transparent glass body, and gelling the sol under centrifugal force using silica fine particles of uniform particle size as a raw material. Method for manufacturing quartz glass.