Five different fused silica types were evaluated for their resistance to UV-induced compaction and color center formation at 193-nm. Real-time monitoring of color- center-induced absorption showed three distinct dependencies of transmission on pulse count. The initial rates of color center formation varied by well over a factor of ten between the materials tested while compaction-induced birefringence rates varied by at most a factor of four. Of the likely candidates for lithographic applications, Corning Excimer Grade 7940 fused silica was the least prone to color center formation while Suprasil 311 showed the lowest compaction rates. The rates of compaction-induced birefringence and color-center-induced absorption from 213-nm radiation were found to increase dramatically under elevated sample temperature conditions. Since a two- photon absorption mechanism is believed to be the catalyst for UV damage to fused silica, two-photon absorption coefficients were characterized at elevated temperatures. The two-photon coefficients at 213-nm for all materials measured including crystalline quartz and under all applied conditions were statistically equivalent, leading to the conclusion that the energy dissipation mechanism, in addition to two-photon absorption, is important to UV damage to fused silica.

Date Published: 14 July 1995
PDF: 11 pages
Proc. SPIE 2428, Laser-Induced Damage in Optical Materials: 1994, (14 July 1995); doi: 10.1117/12.213726

Published in SPIE Proceedings Vol. 2428:
Laser-Induced Damage in Optical Materials: 1994
Harold E. Bennett; Arthur H. Guenther; Mark R. Kozlowski; Brian Emerson Newnam; M. J. Soileau, Editor(s)