Highly Selective Dry Etching of GaN over AlGaN Using Inductively Coupled Cl2/N2/O2Plasmas

Abstract

A systematic study of the selective etching of GaN over Al_0.28Ga_0.72N was performed using Cl₂/N₂/O₂ inductively coupled plasmas (ICP). Highly selective etching at high GaN etch rate is realized by optimizing the O₂ flow rate, the ICP power and the chamber pressure. Maximum etching selectivity of about 60:1 at a GaN etch rate of 320 nm/min has been demonstrated. X-ray photoelectron spectroscopy (XPS) analysis shows that the effective oxidation of AlGaN due to the addition of a small fraction of O₂ is crucial to obtain highly selective etching at high GaN etch rate.