Anisotropic non-plasma HCl gas etching of a (010) β-Ga<sub>2</sub>O<sub>3</sub> substrate
Takayoshi Oshima, Yuichi Oshima
Abstract
Abstract We demonstrated the effectiveness of plasma-free HCl gas etching on a SiO 2 -masked (010) β -Ga 2 O 3 substrate. The etching process proceeded anisotropically in the window areas, resulting in the fabrication of holes or trenches that were surrounded by etching-resistant (100)- and ( <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mover accent="true"> <mml:mn>1</mml:mn> <mml:mo>¯</mml:mo> </mml:mover> </mml:math> 01)-faceted sidewalls. When we etched in the striped windows along [001], we were able to create fins and trenches with flat (100)-faceted vertical sidewalls and slightly rough {310}-faceted inclined bottom corners. The vertical-to-horizontal etching ratio was as high as ∼11–14. Our findings indicate that HCl etching is a promising method for fabricating high-aspect-ratio fins/trenches on (010) substrates without causing plasma damage.