Excimer-laser-induced degradation of fused silica and calcium fluoride for193-nm lithographic applications

We report the initial results of a large-scale evaluation of production-gra de fused silica and calcium fluoride to be used in 193-nm lithographic appl ications. The samples have been provided by many different suppliers of mat erials. A marathon irradiation chamber permits simultaneous exposure of as many as 36 samples at 800 Hz, at fluences from 0.2 to greater than or equal to 4 (mJ/cm(2))/pulse and pulse counts in excess of 10(9). The initial abs orption and the laser-induced absorption are found to vary over a wide rang e. The compaction of each fused-silica sample follows a power law, but its parameters can differ widely from sample to sample. (C) 1999 Optical Societ y of America.