Inductively coupled plasma etching of bulk 6H-SiC and thin-film SiCN in NF3 chemistries

A parametric study of the etching characteristics of 6H p(+) and n(+) SiC and thin-film SiC0.5N0.5 in inductively coupled plasma (ICP) NF3/O-2 and NF3/Ar discharges has been performed. The etch rates in both chemistries increase monotonically with NF3 percentage and rf chuck power. The etch rates go through a maximum with increasing ICP source power, which is explained by a trade-off between the increasing ion flux and the decreasing ion energy. The anisotropy of the etched features is also a function of ion flux, ion energy and atomic fluorine neutral concentration. Indium-tin-oxide masks display relatively good etch selectivity over SiC (maximum of similar to 70:1), while photoresist etches more rapidly than SiC. The surface roughness of SiC is essentially independent of plasma composition for NF3/O-2 discharges, while extensive surface degradation occurs for SiCN under high NF3:O-2 conditions. (C) 1998 American Vacuum Society. [S0734-2101(98) 10104-5].