Micro-machinability of monocrystal silicon by direct etching using excimer laser

The high flexibility of laser direct writing and its potential capability of fabricating micro-mechanical structure are discussed. Aiming at providing knowledge for micro-engineering application, experiments on direct etching of monocrystal silicon with focusing KrF excimer laser beam (λ = 248 nm) were carried out. The validity of non-thermal excimer laser material processing was examined by SEM observation on the “heat-affected zone (HAZ)”. An empirical formula establishing the relationship of etching depth versus laser energy per pulse and the number of laser pulses has been derived from the experiments. Impact damage at the underside of silicon wafer has been observed. Its relevant causes are analyzed.