Wet Chemical and Plasma Etching of Ga2 O 3 ( Gd2 O 3 )

Gallium arsenide metal oxide semiconductor field effect transistors (GaAs MOSFETs) were successfully demonstrated with a specially formulated gallium oxide/gadolinium oxide as the gate dielectric material. For the fabrication of MOSFETs, dry and wet etching of Ga 2 O 3 ( Gd 2 O 3 ) has been investigated. The content of Gd 2 O 3 in the oxide is dependent on the deposition conditions and can vary from 10 to approximately 44%. The etching characteristics of the Ga 2 O 3 ( Gd 2 O 3 ) film is affected by the content of Gd. An HCl based wet etch shows smooth surface morphologies of Ga 2 O 3 ( Gd 2 O 3 ) and would not attack the underlying GaAs. The etch rate of Ga 2 O 3 ( Gd 2 O 3 ) is linearly proportional to the concentration of HCl. Furthermore, the etching was determined to be a reaction‐limited process. For dry etching, the rates for both SF 6 and BCl 3 based discharges are very low due to the incorporation of Gd and the lack of etch selectivity to the GaAs substrate.