PHOTOOXIDATION OF GAAS AND INSITU ELECTRON-BEAM-INDUCED CHLORINE ETCHING

The durability of GaAs oxide layers to chlorine gas exposure was compared for the cases of photo-oxidation and thermal oxidation at room temperature. The GaAs oxide layer formed by photo-oxidation was found to be more durable to chlorine gas exposure, hence a photo-oxidized GaAs layer is suited to use as an inorganic mask. The time required to locally remove the oxide layer by simultaneous irradiation with chlorine molecules and an electron beam (EB) for patterning depended on the conditions of formation of the oxide layer, and was inversely proportional to the EB current density for the fixed GaAs oxide layer. The etch rate of GaAs increased with increasing EB density under constant chlorine irradiation.