Selective Etching of GaN over AlxGa1-xN Using Reactive Ion Plasma of Cl2/CH4/Ar Gas Mixture

Abstract

Reactive ion etching (RIE) of GaN and AlxGa1-xN has been investigated using Cl2, CH4 and Ar gas mixtures. It has been found that a variation in the CH4 percentage in the gas mixture leads to a change in the etch rate of both GaN and Al0.85Ga0.15N with a etch selectivity of 4.2:1 for GaN over AlxGa1-xN for an optimum value of 2.5% of CH4. This gas composition also yields an anisotropic and smooth etching profile. An etch rate of 257 nm/min of GaN has been obtained which is the highest value ever reported with the RIE technique.