Dry Etching of III-V Nitrides

ABSTRACTThe chemical inertness and high bond strengths of the III-V nitrides lead to slower plasma etching rates than for more conventional III-V semiconductors under the same conditions. High ion density conditions (>3×1011cm−3) such as those obtained in ECR or magnetron reactors produce etch rates up to an order of magnitude higher than for RIE, where the ion densities are in the 109 cm−3 range. We have developed smooth anisotropic dry etches for GaN, InN, AlN and their alloys based on Cl2/CH4/H2/Ar, BCl3/Ar, Cl2/H2, C12/SF6, HBr/H2 and HI/H2 plasma chemistries achieving etch rates up to ∼4,000Å/min at moderate dc bias voltages (≤-150V). Ion-induced damage in the nitrides appears to be less apparent than in other III-V’s. One of the key remaining issues is the achievement of high selectivities for removal of one layer from another.