ICP etching of GaN, Al0.1Ga0.9N, and a laser diode (LD) structure with Cl-2-Ar plasma assisted by Si coverplate material was systematically studied. The influence of the process pressure, rf and ICP power on the etch rate, surface morphology, and selectivity to the SiO2 mask was investigated. Smooth anisotropic etch profiles and smooth etch surfaces were obtained for a wide range of process parameters. It was found that an ICP plasma source employed in the particular system used does not significantly effect the sheath ion density and cathode dc-bias, due to the remote location of it. However, the ICP source generates a large amount of reactive radicals, which facilitate fast and smooth etching of Al-containing layers. (c) 2005 American Vacuum Society.