Excimer-laser-induced degradation of fused silica and calcium fluoride for 193-nm lithographic applications

We report the initial results of a large-scale evaluation of production-grade fused silica and calcium fluoride to be used in 193-nm lithographic applications. The samples have been provided by many different suppliers of materials. A marathon irradiation chamber permits simultaneous exposure of as many as 36 samples at 800 Hz, at fluences from 0.2 to > or =4 (mJ/cm(2))/pulse and pulse counts in excess of 10(9) . The initial absorption and the laser-induced absorption are found to vary over a wide range. The compaction of each fused-silica sample follows a power law, but its parameters can differ widely from sample to sample.