Laser-assisted etching-like damage of Si

Abstract

Experimental results are presented on localized Si damage induced by high repetition rate copper-vapor laser pulses under a liquid layer. The damage is confined to the laser spot and is supposed to be due to accumulation of defects in the Si surface layer and material fatigue. These defects are dislocations with lateral dimensions close to that of the laser spot. The time of damage increases exponentially with the decrease of the energy density of the laser pulse and does not depend on the crystallographic orientation of the Si wafer. The rate of etching-like damage in electrolytes increases with external polarization of the Si wafer. The laser writing of porous Si is observed in a certain range of anodic polarization of a Si wafer at scanning velocities of the laser beam of 30–300 μm/s with a spatial resolution of ∼ 20 μm.