Sputtering of solid argon by keV electrons

Thermochemical maskless etching of compound semiconductors (GaAs, InP, InSb, and GaP) has been performed by focused Ar-laser irradiation in chloride gas atmospheres. A controlled minimum linewidth of down to 0.6 m with a maximum etching rate of up to 13 m/s has been obtained. Minimum laser powers necessary for thermochemical etching in each of compound semiconductors were found to be 0.24, 0.56, and 0.06 W, corresponding to minimum local temperature rises of 190, 515, and 110°C for GaAs, InP, and InSb, respectively. Etching rates exhibited Arrhenius behavior with activation energies of 3.6–3.9 kcal/mole. Etching at excessively higher laser powers than those minimum powers was found, by microprobe photoluminescence measurements, to degrade the optical quality of the etched substrate.