Anomalous regimes for GaAs etching in Cl2–Ar plasmas

GaAs etching process has been studied in Ar–Cl2 rf discharges at 200 mTorr as a function of gas composition, substrate temperature, and bias voltage. Actinometric optical emission spectroscopy has been utilized for gas phase diagnostic. Surface analysis has been carried out by x-ray photoelectron spectroscopy and scanning electron microscopy. Anomalies found in the etching regimes have been interpreted as caused by the presence of an inhibiting oxide–chloride film and by the desorption of chlorine adsorbed on the surface by low-energy bombarding ions.