Electron Cyclotron Resonance Plasma Etching of AlGaN in Cl2/Ar and BCl3/Ar Plasmas

Abstract

A comparison of etch rates for alloys was performed in /Ar and /Ar electron cyclotron resonance plasmas. The etch rates were generally found to decrease with increasing AlN concentration, due to the increasing average bond strengths at higher Al compositions. The fastest rates were found in the /Ar chemistry, with rates of ∼3500 Å/min for GaN, 1700 Å/min for AlN, 2500 Å/min for , and 3300 Å/min for . The etched surfaces were also smoother with the /Ar plasma chemistry than the /Ar plasma chemistry. The etch selectivities for GaN over , and AlN were quite low, ⩽5 for all conditions, and this is due to the ion‐driven nature of the removal mechanism.