Etching of 6H-SiC and 4H-SiC using NF3 in a reactive ion etching system

The use of pure NF3 source gas in reactive ion etching of bulk and epitaxy, Si-face, 6H-SiC, and 4H-SiC is reported. The effects of RF power and chamber pressure on etch rate and surface morphology are discussed. A process developed for a smooth, residue-free etch, with a relatively high etch rate of similar to 1500 Angstrom/min is examined using scanning electron microscopy and Auger electron spectroscopy surface analysis. The process developed had a self-induced de bias ranging from 25 to 50 V, a forward RF power of 275 W (1.7 W/cm(2)), chamber pressure of 225 mT, and a NF3 now rate between 95 and 110 seem. No chemical residue or aluminum micromasking was observed on any of the samples etched with the above process.