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

A systematic study of the selective etching of GaN over Al 0.28 Ga 0.72 N was performed using Cl 2 /N 2 /O 2 inductively coupled plasmas (ICP). Highly selective etching at high GaN etch rate is realized by optimizing the O 2 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 O 2 is crucial to obtain highly selective etching at high GaN etch rate.