High‐Density Etching of Group III Nitride Ternary Films

Due to their wide bandgaps and high dielectric constants, group III nitrides have made significant impact on the compound semiconductor community as blue, green, and ultraviolet light emitting diodes and for their potential use in laser structures and high temperature electronics. Processing of these materials, in particular wet and dry etching, has proven to be extremely difficult due to their inert chemical nature. The authors report electron cyclotron resonance etching of In{sub x}Ga{sub 1{minus}x}N and In{sub 0.75}Al{sub 0.25}N as a function of temperature, RF power, pressure, and microwave power. Etch conditions were characterized for rate, profile, and sidewall and surface morphology and compared to etch data for GaN, InN, and AlN. Atomic force microscopy was used to quantify root-mean-square roughness of the etched surfaces. The authors observed consistent trends for the InAlN films where the etch rates increased with increasing concentration of In. The trends were less consistent for the InGaN etch rates.