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Proceedings Paper

Marathon testing of optical materials for 193-nm lithographic applications
Author(s): Vladimir Liberman; Mordechai Rothschild; Jan H. C. Sedlacek; Ray S. Uttaro; Allen Keith Bates; Chris K. Van Peski
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Paper Abstract

We have undertaken a systematic evaluation of both bulk material sand optical coatings designed for 193-nm lithographic applications. These studies are performed at realistic fluences and pulse counts in excess of 109. Measurements of absorption is fused silica show a large variation in performance for different samples in both initial and laser-induced absorption. Calcium fluorides samples show less variation in laser-induced absorption and appear to be more stable under irradiation of 0.2-1 billion pulses. Laser-induced densification of fused silica appears to follow an empirical power law; however, an order of magnitude spread in densification is observed among grades. For optical antireflectance coatings, we have characterized the initial 'laser-cleaning' phenomenon for various coatings. We have observed that laser-cleaned coatings deposited on CaF2 substrates exhibit higher initial optical losses at 193 nm than their counterparts on SiO2 substrates. However, the losses for coatings on CaF2 substrates are reduced over irradiation times of 0.2-1 billion pulses to final values comparable to their SiO2 counterparts. Finally, we have characterized various catastrophic failures of coating material, such as induced losses, adhesion failure and laser-induced thinning.

Paper Details

Date Published: 7 April 1999
PDF: 14 pages
Proc. SPIE 3578, Laser-Induced Damage in Optical Materials: 1998, (7 April 1999); doi: 10.1117/12.344432
Show Author Affiliations
Vladimir Liberman, MIT Lincoln Lab. (United States)
Mordechai Rothschild, MIT Lincoln Lab. (United States)
Jan H. C. Sedlacek, MIT Lincoln Lab. (United States)
Ray S. Uttaro, MIT Lincoln Lab. (United States)
Allen Keith Bates, IBM/International SEMATECH (United States)
Chris K. Van Peski, International SEMATECH (United States)

Published in SPIE Proceedings Vol. 3578:
Laser-Induced Damage in Optical Materials: 1998
Gregory J. Exarhos; Arthur H. Guenther; Mark R. Kozlowski; Keith L. Lewis; M. J. Soileau, Editor(s)

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