Title:
DETECTION AND MAKING OF ULTRALOW LEAD CONTAMINATED UV OPTICAL FLUORIDE CRYSTALS FOR < 200 NM LITHOGRAPHY
Document Type and Number:
WIPO Patent Application WO2004015453
Kind Code:
A3
Abstract:
The invention provides a method of detecting sub-ppm lead impurity levels in a below 200 nm transmitting optical calcium fluoride crystal. The method includes providing a below 200 nm wavelength transmitting optical calcium fluoride crystal (20), providing a fluorescence spectrometer (22) having a light source (24) for producing a 100 to 210 nm selectable wavelength incident radiation and a detector (28) for detecting excited luminescence light in the wavelength range of 210-260 nm produced by the incident radiation, exciting a first luminescence area of the crystal with the 200 to 210 nm selectable wavelength incident radiation and detecting with the detector excited 210 to 260 luminescence light produced from the crystal luminescence area by the 200 to 210 incident radiation to provide a lead ppb impurity level measurement less than 100 ppb. The invention provides for improved manufacturing of below 200 nm wavelength optical elements and optical fluoride crystals such as ultralow lead contaminated calcium fluoride.
Inventors:
MAYOLET ALEXANDRE MICHEL
TIMOFEEV NIKOLAY T
TIMOFEEV NIKOLAY T
Application Number:
PCT/US2003/022975
Publication Date:
October 14, 2004
Filing Date:
July 24, 2003
Export Citation:
Assignee:
CORNING INC (US)
International Classes:
G01N21/64; G01N21/00; (IPC1-7): G01N21/64
Foreign References:
| US4562356A | 1985-12-31 | |||
| US6226128B1 | 2001-05-01 |
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