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US 5,958,809 AGranted
Fluorine-containing silica glass
AssigneeNikon Corporation
InventorsSeishi Fujiwara, Hiroyuki Hiraiwa, Kazuhiro Nakagawa, Shouji Yajima, Norio Komine, Hiroki Jinbo
Life of this patent
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Abstract
The invention relates to fluorine-containing silica glasses, and methods of their production. The silica glass may be used for an ultraviolet light optical system in which light in a wavelength region of 200 nm or less, such as an ArF (193 nm) excimer laser, is used. The invention also relates to a projection exposure apparatus containing fluorine-containing glass of the invention.
Claims7
A fluorine-containing silica glass comprising:
- a silica glass having a hydrogen molecule concentration ranging from about 2.times.10.sup.17 to 5.times.10.sup.18 molecules/cm.sup.3 and a hydroxyl group concentration ranging from about 600 ppm to 1300 ppm.
A fluorine-containing silica glass comprising:
- silica glass which is substantially free of chlorine and has a structure determination temperature ranging from 900 K. to 1200 K., a fluorine concentration ranging from 10 to 1000 ppm, a hydroxyl group concentration ranging from 600 to 1300 ppm and a hydrogen molecule concentration ranging from 2.times.10.sup.17 to 5.times.10.sup.18 molecules/cm.sup.3.
Dependencies are inferred from the claim text.