Highly Selective Dry Etching of GaN over AlGaN Using Inductively Coupled Cl2/N2/O2 Plasmas

Abstract

A systematic study of the selective etching of GaN over Al0.28Ga0.72N 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.