Organic acid-based wet etching behaviors of Ga-doped ZnO films sputter-deposited at different substrate temperatures

Abstract

150 nm thick Ga-doped ZnO (GZO) thin films were sputter-deposited at different substrate temperatures of 200 °C and room temperature (RT). Different degrees of crystallinity, electrical resistivities, and surface topologies resulted between these as-deposited GZO films. Weak organic acid-based etchants such as citric and formic acids with the identical concentration of 0.02 M were chosen for line-patterning of GZO films, and their etching results were found to be strongly dependent on the crystallinity of as-deposited GZO films. The GZO films deposited at 200 °C and RT exhibited a desirable etch profile such as a steep sidewall angle and a straight pattern line by 0.02 M formic and citric acids, respectively. The etch rate, etch profile, and activation energy for 200 °C- and RT-GZO films with organic acids used are compared, and the distinct etching mechanisms between 200 °C- and RT-GZO films are suggested.