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Proceedings Paper

Characterization of striae in ULE for EUVL optics and masks
Author(s): William Rosch; Lorrie Beall; John Maxon; Robert Sabia; Robert Sell
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Paper Abstract

Compositional striations in Corning's Ultra Low Expansion (ULE®) glass are thought to affect the surface roughness when the glass is polished. For EUV Lithography photomask blanks, it is important for the polished surface to be as smooth as possible. Therefore, since the compositional striations may impact photomask polishing, Corning has undertaken an effort to better characterize the striae and its impact on surface roughness, improve the fundamental understanding of its origin during boule formation, and develop methods and procedures to reduce its potential impact on polishing. This work has verified that striae can vary quite a bit throughout a single ULE glass boule. Characterization has shown that there are two main types of striae. These can be described as high frequency (secondary) striae and lower frequency (primary) striae. Due to the new understanding of the striae origin, two methods have recently been identified and used to greatly reduce or eliminate the high frequency striae component. Currently, new modeling efforts have helped identify potential process changes that may reduce the impact of the primary striae frequency. Experiments are in process to determine their effectiveness.

Paper Details

Date Published: 23 March 2006
PDF: 8 pages
Proc. SPIE 6151, Emerging Lithographic Technologies X, 615122 (23 March 2006); doi: 10.1117/12.656355
Show Author Affiliations
William Rosch, Corning Inc. (United States)
Lorrie Beall, Corning Inc. (United States)
John Maxon, Corning Inc. (United States)
Robert Sabia, Corning Inc. (United States)
Robert Sell, Corning Inc. (United States)

Published in SPIE Proceedings Vol. 6151:
Emerging Lithographic Technologies X
Michael J. Lercel, Editor(s)

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