The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Mar. 16, 2004
Filed:
Dec. 27, 2000
Koji Matsuo, Nakakubiki-gun, JP;
Hisatoshi Otsuka, Nakakubiki-gun, JP;
Kazuo Shirota, Nakakubiki-gun, JP;
Shin-Etsu Chemical Co., Ltd., Tokyo, JP;
Abstract
A process for producing synthetic quartz glass using a burner composed of a plurality of concentric nozzles involves the steps of feeding a silica-forming raw material gas and a fluorine compound gas to a reaction zone from a center nozzle, feeding oxygen gas from a second nozzle outside the center nozzle, and feeding oxygen gas and/or hydrogen gas from a third nozzle. The silica-forming raw material gas is hydrolyzed to form fine particles of silica, which particles are deposited on a rotatable substrate so as to form a porous silica matrix, which is then fused to give the quartz glass. The flow rate of the oxygen gas fed from the second nozzle and the flow rate of the raw material gas are controlled so as to provide a 1.1- to 3.5-fold stoichiometric excess of oxygen. The excess oxygen suppresses Si—Si bond formation in the quartz glass, enabling the production of synthetic quartz glass having a high transmittance in the vacuum ultraviolet region.