SMOOTH ETCHING OF SINGLE-CRYSTAL 6H-SIC IN AN ELECTRON-CYCLOTRON-RESONANCE PLASMA REACTOR

Single-crystal 6H-SiC has been etched using a CF4/O2 gas mixture in an electron cyclotron resonance (ECR) plasma reactor. ECR etching results in SiC surfaces which are extremely smooth, without the problematic micromasking effects which have been reported to result from reactive ion etching in capacitively coupled radio-frequency plasma reactors. The effects of microwave power, total pressure, substrate temperature, and substrate bias on the etch rate, surface morphology, etch profile, and etch selectivity have been evaluated. The etch rate increases with increasing power and bias, and decreasing pressure. However, high biases lead to enhanced etching in regions adjacent to sidewall features. Improved etch profiles and selectivity are obtained with lower applied substrate bias.