Fast and anisotropic reactive ion etching of 4H and 6H SiC in NF3

Reactive ion etching of the 4H- and 6H-SiC polytypes in an NF3 plasma under conditions which produce both a high etch rate and highly anisotropic profiles is presented. The effects of flow rate, pressure and power on etch rate and self-induced DC bias are evaluated. Optimum RIE conditions of 80 seem, 80 mTorr and 300 PI (0.6W/cm(2)) produce an etch rate of similar to 1200-1250 Angstrom/min for both polytypes, while generating a DC bias of only similar to 100V. Under these conditions highly anisotropic profiles and residue-free etch fields are obtained. The roughness of the etched surface as measured by AFM was essentially similar tc, that of the as-received surface (similar to 3 Angstrom).