Precision Wet Etching of ZnO Using Buffer Solutions

Zinc oxide (ZnO) is a metal oxide semiconductor of interest for a wide range of electronic and optoelectronic device applications. Many devices require etching of ZnO structures and there have been many investigations of ZnO wet-etching processes. However, most reported etches have problems with reproducibility and especially control of vertical and lateral (or undercut) etching uniformity. In this work, we report new buffer solutions that provide controlled vertical and lateral etching of ZnO. We compare the ZnO etch characteristics of buffer etchants to a previously reported ammonium chloride etch. Using buffer etchants of suitable composition we find reaction-rate-limited, uniform, reproducible etching, and similar vertical and lateral etch rates.