Influence of mask material and process parameters on etch angle in a chlorine-based GaN dry etch.

The vertical structuring of GaN layers for power application purposes is a key step for successful device operation. Thus, the dry etching of GaN becomes a crucial step. While etch rates and surface roughness have been analyzed well, the sidewall angle of the etched GaN has drawn less attention. In this paper, the authors report on the influence of mask material and etch parameters in an inductively coupled plasma reactive ion etching process on the angle of the etched GaN sidewall. Deep etches up to 3.3 μm are shown. The authors show how the sidewall angle can either be adjusted to high values up to 80° or, if necessary, to small angles down to 46°. [ABSTRACT FROM AUTHOR]