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:
Sep. 08, 2009
Filed:
Dec. 21, 2007
Mitsuhiro Kawata, Tokyo, JP;
Akira Takada, Tokyo, JP;
Hideaki Hayashi, Tokyo, JP;
Naoki Sugimoto, Tokyo, JP;
Shinya Kikugawa, Tokyo, JP;
Mitsuhiro Kawata, Tokyo, JP;
Akira Takada, Tokyo, JP;
Hideaki Hayashi, Tokyo, JP;
Naoki Sugimoto, Tokyo, JP;
Shinya Kikugawa, Tokyo, JP;
Asahi Glass Company, Limited, Tokyo, JP;
Abstract
It is to obtain a silica glass suitable as a material for an optical material constituting an optical system to be used for EUVL, which has a low coefficient of thermal expansion from 0 to 100° C., and on which formation of concave defects is suppressed in a polishing step to achieve a high level of flatness. A silica glass containing from 0.1 to 10 mass % of Sn calculated as SnOand from 3 to 10 mass % of Ti calculated as TiO, which has a homogeneity of the coefficient of thermal expansion from 0 to 100° C. to the temperature of from 50 to 200 ppb/° C., a coefficient of thermal expansion from 0 to 100° C. of 0±250 ppb/° C., and a Vickers hardness of at most 650.