Growth of A1N on patterned sapphire substrates was studied. Deep grooves were made on sapphire substrates by a laser-induced backside wet etching technique. KrF excimer laser was irradiated at an interface between sapphire and phenolphthalein/N-methyl-2-pyrrolidone solution, which acts as a super-heating liquid. An etch rate of sapphire was as high as 6μm/min for laser power of 1.0J/cm 2 . The A1N layer was grown on the patterned sapphire substrate by chemical vapor reaction process at 1190°C for 1h. On the inclined sidewall of the etched grooves, A1N grew with its c-axis perpendicular to the sidewall. This produced m-plane surfaces which were inclined around 20° to the basal plane of sapphire. A threading dislocation density of m-plane A1N domains was 8×10 8 cm −2 .