Inductively Coupled Plasma Reactive Ion Etching of (−201) β‐Ga₂O₃ Nano‐Fins

This study reports the effect of inductively coupled plasma reactive ion etching using a BCl 3 /Ar gas mixture on the sidewall taper angle (STA), etch rate, and surface morphology of (−201) β‐Ga 2 O 3 substrates, as well as (−201)‐oriented β‐Ga 2 O 3 films on sapphire, for nano‐fins of ≈200 nm width. Various etch parameters are systematically investigated for the β‐Ga 2 O 3 films on sapphire, revealing that the STA is lower at high plasma density when chemical component increases, and the ion scattering decreases; achieving a STA of 1.5° ± 0.7°, accompanied by an etch rate of 114 nm min −1 and a reduction in surface roughness compared to before etching. Additionally, a strong positive correlation between the STA and the crystal orientation in the β‐Ga 2 O 3 substrates is observed at lower plasma density, while a weak correlation is found between the STA and the crystal orientation at high plasma density. This study provides valuable insights for the fabrication of β‐Ga 2 O 3 devices.