Estimation of the Life of Synthetic Silica Glass under Long Time Irradiation by ArF Excimer Laser

Abstract

The life of synthetic silica glass under ArF excimer laser irradiation was estimated in relation to the laser energy density by in-situ photoabsorption measurements under exposure to more than 107 shots. Dissolved hydrogen increases the life whereas OH in the glass scarcely influences it. Usual photomask glass is found to be tolerable to more than 1011 shots at 0.1 mJ/cm2 of laser irradiation intensity.

Coefficients of stationary ArF laser pulse absorption in fused silica (type III)

“…DUV laser pulses, however, induce two photon absorption in fused silica resulting in its long term optical degradation. To predict long term stability of fused silica, material tests are carried out applying up to 10 10 laser pulses [1][2][3][4]. Beyond these long term optical degradation it is also necessary to consider the changes of optical properties on the much shorter second-to-minute time scale, commonly depicted as rapid damage [5,6].…”

Generation and annealing of defects in virgin fused silica (type III) upon ArF laser irradiation: Transmission measurements and kinetic model

“…It is assumed that this results in the much higher a max value of sample 3 compared to samples 1 and 2. In contrast, the lower intermediate a max value of sample 1 compared to sample 2 is probably due to the lower [P 3 ] 0 and g [P 4 ] 0 values of sample 1.…”

“…Over long irradiation periods this yields an absorption increase due to defect formation and a refractive index change due to microscopic structural rearrangements limiting the lifetime of optical components. In order to proof and to model the long term laser stability of fused silica, material tests are carried out with up to 10 10 laser pulses and intermediate transmission and/or refractive index measurements [3][4][5][6][7][8]. Besides long term optical degradation, however, it is necessary to investigate the optical properties on the much shorter second-to-minute time scale, commonly depicted as rapid damage regime [9,10].…”