REACTIVE ION ETCHING OF III-V NITRIDES

The chemical inertness and high bond strengths of the III-V nitrides l ead to slower plasma etching rates than for more conventional III-V se miconductors under the same conditions. High ion density conditions (> 3 x 10(11) cm(-3) ) such as those obtained in ECR or magnetron reactor s produce etch rates up to an order of magnitude higher than for RIE, where the ion densities are in the 10(9)cm(-3) range. We have develope d smooth anisotropic dry etches for GaN, InN, AIN and their alloy base d on Cl-2/CH4/H-2/Ar, BCl3/Ar, Cl-2/H-2, Cl-2/SF6, HBr/H-2 and HI/H-2 plasma chemistries achieving etch rates up to similar to 4000 Angstrom /min at moderate d.c. bias voltages (less than or equal to -150 V). Io n-induced damage in the nitrides appears to be less apparent than in o ther III-Vs. One of the key remaining issues is the achievement of hig h selectivities for removal of one layer from another. (C) 1997 Elsevi er Science Ltd.