Effect of the temperature and HCl partial pressure on selective-area gas etching of (001) β-Ga₂O₃

Abstract We investigated the anisotropic selective-area HCl-gas etching behavior of SiO 2 -masked (001) β -Ga 2 O 3 and its dependence on the temperature T (548 °C–949 °C) and HCl partial pressure P 0 (HCl) (25–250 Pa). The cross-sectional width-to-depth aspect ratio of the etched trenches formed under the striped window along [010] decreased with increasing T and decreasing P 0 (HCl). Secondary-ion mass spectrometry revealed slight diffusion of Si into β -Ga 2 O 3 at T = 949 °C, while no diffusion was detected at T = 750 °C. These results provide practical guidelines for the fabrication of desired three-dimensional structures, such as fins/trenches, for high-performance β -Ga 2 O 3 -based power devices.