Effects of BCl3 addition to Cl2 gas on etching characteristics of GaN at high temperature

Abstract

Gallium nitride films were etched at 400 °C and 20 Pa with a radio-frequency-generated Cl2–BCl3 mixed plasma. While dog-legged profiles were obtained by plasma etching using pure Cl2, straight sidewall shapes were achieved through BCl3 gas addition into the Cl2 plasma by suppressing the plasma-induced damage on the etched surface. Etching by-products containing boron on the etched surface affected the etch rate. Smooth etched profiles were obtained by controlling the redeposition of by-products of boron and chlorine compounds, particularly for substrate temperatures above 230 °C.