Temperature-dependence of Cl2/Ar ICP-RIE of polar, semipolar, and nonpolar GaN and AlN following BCl3/Ar breakthrough plasma

Abstract

The authors report a comprehensive investigation of temperature-dependence of inductively coupled plasma reactive ion etching (ICP-RIE) of polar (0001), semipolar (11−22), and nonpolar (11−20) GaN and AlN, in the temperature range of 22–205 °C. The main objective is to study the effect of ICP etching near and beyond the boiling point of the volatile etch end-products: GaCl3 (201 °C) for GaN and AlCl3 (180 °C) for AlN. High-temperature ICP-RIE is beneficial in quicker removal of surface oxides and may permit the use of a single-step Cl2/Ar ICP-RIE for etching all orientations of GaN and AlN. However, the best results are still obtained with a combination of BCl3-plasma based surface oxide removal pretreatment and Cl2/Ar ICP-RIE etching, which provides a constant etch rate with a smooth surface morphology irrespective of the etching temperature.