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Proceedings Paper

Two-photon equivalent weighting of spatial excimer laser beam profiles
Author(s): Eric Eva; Harry H. Bauer; K. Metzger; A. Pfeiffer
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Paper Abstract

Damage in optical materials for semiconductor lithography applications caused by exposure to 248 or 193 nm light is usually two-photon driven, hence it is a nonlinear function of incident intensity. Materials should be tested with flat- topped temporal and spatial laser beam profiles to facilitate interpretation of data, but in reality this is hard to achieve. Sandstrom provided a formula that approximates any given temporal pulse shape with a two- photon equivalent rectangular pulse (Second Symposium on 193 nm Lithography, Colorado Springs 1997). Known as the integral-square pulse duration, this definition has been embraced as an industry standard. Originally faced with the problem of comparing results obtained with pseudo-Gaussian spatial profiles to literature data, we found that a general solution for arbitrarily inhomogeneous spatial beam profiles exists which results in a definition much similar to Sandstrom's. In addition, we proved the validity of our approach in experiments with intentionally altered beam profiles.

Paper Details

Date Published: 12 April 2001
PDF: 2 pages
Proc. SPIE 4347, Laser-Induced Damage in Optical Materials: 2000, (12 April 2001); doi: 10.1117/12.425074
Show Author Affiliations
Eric Eva, Carl Zeiss (Germany)
Harry H. Bauer, Carl Zeiss (Germany)
K. Metzger, Carl Zeiss (Germany)
A. Pfeiffer, Ludwig-Maximilians-Univ. Muenchen (Germany)

Published in SPIE Proceedings Vol. 4347:
Laser-Induced Damage in Optical Materials: 2000
Gregory J. Exarhos; Arthur H. Guenther; Mark R. Kozlowski; Keith L. Lewis; M. J. Soileau, Editor(s)

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