A durability study performed by International Sematech Inc. of Austin, Texas, has found that Corning HPFS glass performs well under exposure to 193-nm light, said Corning Inc. of Corning, N.Y. The study examined the performance of fused silica samples from five manufacturers in a scaling law test, designed to simulate the effects of argon-fluoride laser radiation on exposure lenses for 193-nm semiconductor lithography. Corning's glass displayed no trend in wavefront distortion after 14 billion pulses, showing densification of less than 10 nm. Exposure at fluence levels of between 0.0063 and 0.12 mJ/cm2 had little effect on wavefront distortion through 22 billion pulses.