Titania-doped quartz glass and making method

Patent metadata

Field	Value
Publication number	US-9746773-B2
Application number	US-201313920628-A
Country	US
Kind code	B2
Filing date	Jun 18, 2013
Priority date	Dec 25, 2009
Publication date	Aug 29, 2017
Grant date	Aug 29, 2017

Abstract

Methods for selecting titania-doped quartz glass which experiences a reduction in OH group concentration of less than or equal to 100 ppm upon heat treatment at 900° C. for 100 hours as suitable material for the EUV lithography member.

First claim

The invention claimed is:

1. A method of selecting a titania-doped quartz glass having a reduction in OH group concentration of less than or equal to 100 ppm, comprising
measuring a sample taken from a titania-doped quartz glass ingot to be selected for OH group concentration,
heat-treating the sample of the titania-doped quartz glass ingot at 900° C. for 100 hours,
measuring the heat-treated sample for OH group concentration,
computing a reduction of OH group concentration to evaluate the sample whether the reduction of OH group concentration is less than or equal to 100 ppm or not
selecting the titania-dope quartz glass ingot whose sample had a reduction of OH group concentration less than or equal to 100 ppm and then shaping the selected ingot into a predetermined shape,
wherein said titania-doped quartz glass ingot being prepared by a method comprising the steps of
subjecting a silicon-providing reactant gas and a titanium-providing reactant gas to oxidation or flame hydrolysis with the aid of a combustible gas and a combustion-supporting gas, to thereby form synthetic silica titania fine particles,
depositing the silica-titania fine particles on a rotating target, and

concurrently melting and vitrifying the deposited particles into titania-doped quartz glass.

2. The method of claim 1 wherein the titania-doped quartz glass to be selected further has a difference between maximum and minimum reductions of OH group concentration upon the 900° C./100-hour heat treatment of less than or equal to 50 ppm.

3. The method of claim 1 wherein the titania-doped quartz glass to be selected further has an OH group concentration of 300 ppm to 950 ppm after the 900° C./100-hour heat treatment.

4. The method of claim 1 wherein the titania-doped quartz glass to be selected further has an OH group concentration gradient of less than or equal to 100 ppm/cm after the 900° C./100-hour heat treatment.

5. The method of claim 1 wherein the method of preparing the titania-doped quartz glass ingot further comprises a step of feeding oxygen gas as the combustion supporting gas through a central tube of a burner in admixture with the silicon-providing reactant gas and the titanium-providing reactant gas in a molar ratio of oxygen gas to the sum of the silicon-providing reactant gas and the titanium-providing reactant gas of at least 5, and/or a step of injecting hydrogen gas as the combustible gas through one or more hydrogen gas feed tubes of the burner at a linear velocity of less than or equal to 100 m/sec.

6. The method of claim 5 , wherein the molar ratio of oxygen gas to a sum of the silicon-providing reactant gas and the titanium-providing reactant gas is no more than 30.

7. The method of claim 5 , wherein the molar ratio of oxygen gas to a sum of the silicon-providing reactant gas and the titanium-providing reactant gas is at least 10.

8. The method of claim 5 , wherein the molar ratio of oxygen gas to a sum of the silicon-providing reactant gas and the titanium-providing reactant gas is no more than 20.

9. The method of claim 1 wherein in the method of preparing the titania-doped quartz glass ingot, flow rates of the combustible gas, the combustion-supporting gas, the silicon-providing reactant gas and the titanium-providing reactant gas are controlled so that respective variations of the flow rates may fall within ±1%, temperatures of cooling air introduced into a quartz glass manufacturing furnace from outside, exhaust gas from the furnace, and ambient air surrounding the furnace are controlled so that respective variations of the temperatures may fall within ±2.5° C., and the rotating target is rotated at a rotational speed of at least 5 rpm when the silica-titania fine particles are deposited on the rotating target.

Assignees

• Shinetsu Chemical Co

Inventors

• Maida Shigeru
• Otsuka Hisatoshi
• Ueda Tetsuji
• Ezaki Masanobu

Classifications

• C03B2207/06

  Concentric circular ports · CPC title

• G03F7/2008 Primary

  characterised by the reflectors, diffusers, light or heat filtering means or anti-reflective means used · CPC title

• C03B19/1423

  Reactant deposition burners · CPC title

• G03F1/24

  Reflection masks; Preparation thereof · CPC title

• C03B2207/12

  Nozzle or orifice plates · CPC title