Low damage and residue-free dry etching of 6H-SiC using electron cyclotron resonance plasma

Dry etching-induced surface damage and contamination on SiC have been investigated for electron cyclotron resonance (ECR) plasma etching and conventional reactive ion etching (RIE) using a CF₄/O₂ gas mixture. Auger electron spectroscopy shows that there is no residue on the ECR etched surfaces and sidewalls of the etched structures. In contrast, the conventional RIE process leaves residues containing large amounts of Al, F, and O impurities on the surfaces and the etched sidewalls. Pd Schottky diodes on the ECR etched surface show a near-ideal diode characteristics with ideality factor of 1.06, indicating a good surface quality. Pd Schottky diodes on the conventional RIE etched surface, however, have a substantially reduced barrier height from 1.05 eV for the as-grown sample to 0.64 eV and a high ideality factor of 1.27, indicating a substantially damaged surface. Significant free-carrier reduction is observed in the RIE etched sample.