Selective Dry Etching of AlGaAs-GaAs Heterojunction

Abstract

Selective dry etching of GaAs to Al _x Ga_1-x As (x=0.3) using an etching gas composed of CCl₂F₂ and helium was studied. Etching was carried out at gas composition ratios of P CCl₂F₂ /P _He above 0.25, total pressures of 0.5 to 5.0 Pa, and power densities of 0.18 to 0.53 W/cm². A high selectivity ratio exceeding 200 and a clean etch profile were obtained at a gas composition ratio of P CCl₂F₂ /P _He=1 operated at 5 Pa and 0.18 W/cm². The etched profile of GaAs under the above conditions exhibited a nearly vertical-wall character.