HIGH-DENSITY PLASMA-ETCHING OF III-V NITRIDES

Two broad classes of plasma chemistry were examined for dry etching of GaN, ALN, and InN. The etch rates for CH4/H-2-based plasmas are low ( similar to 400 Angstrom/min) even under high microwave power (1000 W) electron cyclotron resonance conditions. Halogen-based plasmas (Cl-2, I-2, Br-2) produce rates up to similar to 3000 Angstrom/min with smoot h stoichiometric surfaces. Preferential sputtering of N occurs for hig h ion energies, leading to rough GaN surfaces at rf power above simila r to 200 W. Etch rates for high ion density discharges are typically a n order of magnitude faster than for conventional reactive ion etching . (C) 1996 American Vacuum Society.