Using selective-area growth and selective-area etching on (−102) β-Ga2O3 substrates to fabricate plasma-damage-free vertical fins and trenches

We have demonstrated selective-area growth and selective-area etching on SiO2-masked (−102) β-Ga2O3 substrates using a HCl-based halide-vapor-phase epitaxy system that is capable of performing both growth and gas etching without plasma excitation. Since the surface of the (−102) substrate is perpendicular to the (100) plane, which has the lowest surface energy, we were able to use both methods to fabricate plasma-damage-free fins and trenches with (100)-faceted vertical sidewalls on windows striped along the [010] direction with high processing accuracy. Furthermore, since the [010] window direction is aligned parallel to the majority of dislocations and line-shaped voids in the substrate—which extend along the [010] direction and could potentially act as leakage paths—such crystal defects are unlikely to appear on the surfaces of the resulting fins and trenches. We believe that these selective-area growth/etching techniques can greatly accelerate research on, and the development of, β-Ga2O3-based vertical/lateral devices with fins or trenches.