Modification of Fused Silica Materials for Excimer Laser Optics—measurement of laser induced defects and its reformation—

ABSTRACTFused silica is widely used material in window and lens applications for excimer laser processing. The transmittance of the laser beam in fused silica is attenuated approximately 40% by high fluence ArF excimer laser irradiation. The attenuation of the transmittance corresponds to the growth of an absorption band at 215nm. This phenomenon is troublesome for laser lithography. To investigate this effect, we examined the laser induced luminescence and absorption under various conditions. The 215nm absorption band was diminished by annealing at 900 °C for 2 hours in He ambient. Ke could successfully obtain good optical material, whose transmittance remains constant with increasing ArF laser(193nm) shot exposure.