Photostimulated desorption in laser-assisted etching of silicon

Photodesorption of SiF₃ groups, which are the principal adsorbates on a silicon surface during etching by XeF₂, is found to be responsible for the etch-rate enhancement observed under illumination by low-power, cw band-gap radiation. It is proposed that desorption is stimulated by photogenerated-charge-carrier--mediated chemical reaction, and not the simple charge trapping and recombination mechanism usually invoked for desorption from semiconductor surfaces.