Carbon tetrachloride plasma etching of GaAs and InP: A kinetic study utilizing nonperturbative optical techniques

Abstract

CCl4 plasma etching rates of GaAs and InP as a function of substrate temperature, rf power (at 55 kHz), reactor loading, flow, and time are reported. The etching-rate dependence on temperature from 165 to 425 °C is non-Arrhenius. Time-dependent etching-rate data were obtained from In and InCl plasma emission after establishing an empirical proportionality between emission intensity and etching rate. Indium ground state concentration, as measured by laser-induced fluorescence, was found to exhibit the same time dependence as In and InCl plasma emission. For GaAs and InP (above 250 °C), etching reactions are shown to be limited by product and/or reactant diffusion through a passive chlorocarbon film. For InP below 250 °C, time-dependent etching-rate data suggest that this deposited film interacts with InP substrates so as to enhance the etching rate.