Degradation-free electron cyclotron resonance plasma etching of InP
The authors report the first demonstration of featureless surface morphology on InP plasma etched in CH4/H2/Ar electron cyclotron resonance (ECR) discharges. At a plasma composition of 5 CH4/17 H2/8 Ar it is necessary to limit the microwave input power to or=3 compared with CH4/H2 alone, indicating that some additional degree of ion bombardment is necessary with this gas chemistry even under ECR conditions. Degradation of the InP photoluminescence as a result of plasma etching at bias voltages less than 150 V can be completely quenched by the addition of PCl3 to the discharge. This provides a phosphorus partial pressure during the etch, maintaining the stoichiometry of the InP surface.