Micromachining of quartz crystal with excimer lasers by laser-induced backside wet etching

We fabricated a well-defined pattern of lines and spaces on the surface of a quartz crystal plate (c-SiO₂) with micron-sized features, using laser-induced backside wet etching (LIBWE). The line patterns obtained using LIBWE showed a high aspect ratio of about 3. The etch rates of fused silica (a-SiO₂) ranged from 5 to 25 nm/pulse with KrF laser irradiation from 0.4-1.3 J/cm². Threshold fluences for a-SiO₂ and c-SiO₂ were 0.23 and 0.34 J/cm², respectively. The single-pulse etch depth was not affected by the repetition rates of laser pulses from 1-50 Hz.