Selective etching of GaN over AlN using an inductively coupled plasma and an O-2/Cl-2/Ar chemistry

An alternative method for achieving etching selectivity between GaN and AIN has been demonstrated. The etch rate of AW was significantly decreased by the addition of a low concentration of O-2 to a Cl-2-Ar mixture in an induc tively coupled plasma (ICP) etching system. The etch rate of GaN in the O-2 -containing plasma was approximately 15% less than the plasma without the O -2 for the same parameters. The pressure and the ICP power were varied to a chieve a maximum selectivity of 48 at a pressure of 10 mTorr, a direct curr ent bias of - 150 V, and an ICP power of 500 W. The etch rates of GaN and A LN at these parameters were 4800 and 100 Angstrom/min, respectively. (C) 20 00 American Vacuum Society. [S0734-2101(00)01503-7].