he effect of 1 93-nm excimer laser radiation on pellicles designed
for 248-nm use is studied. The pellicles are transparent at 1 93 nm
as well. However, prolonged irradiation causes gradual thinning and
eventual rupture of the pellicle. The rate of change depends on the fluence and on the total dose but is not affected by the presence of atmospheric oxygen. Two-photon absorption plays an important role in the interaction between the laser and the pellicle material. Extrapolation to the approximately 0.1 mJ cm2lpulse fluences expected to be used in
1 93-nm steppers indicates that these pellicles will change little for 5everal
years in a full-production environment.