REACTIVE ION ETCHING OF 6H-SIC IN AN ECR PLASMA OF CF4-O-2 MIXTURES USING BOTH NI AND AL MASKS

We report on the dry etching of 6H-SiC using a RF-biased electron cycl otron resonance plasma and a CF4-O-2 mixture. We have investigated the etching rate dependency on the percentage of oxygen in the gas mixtur e, the total pressure and flow gas. We have found that using a gas mix ture with 40% of O-2 and a residence time of about 1 s, the optimum ra te of etch 6H-SiC crystals grown by the natural Lely method was about 80 nm min(-1). After 20 min of etching, the surface morphology was inv estigated by atomic force microscopy. It was found very satisfactory w ith no evidence of large residues. Finally, the selectivity of Al and Ni masking was investigated. With respect to bulk 6H-SiC, we have foun d about 16 for Al and 40 for Ni. (C) 1997 Elsevier Science S.A.