Pulsed mode atomic layer etching of ScAlN using Cl2/C2H4/Ar

In this work, a pulsed mode atomic layer etching for scandium aluminum nitride (ScAlN) thin films was proposed. Atomic-level precision control over ion-assisted etching and dynamic by-product desorption was achieved by developing a Cl2 + C2H4/Ar cyclical etching process. The introduction of C2H4 etching gas effectively suppresses surface residues originating from ScCl3. Energy-dispersive x-ray spectroscopy analysis reveals negligible changes in the atomic composition during the etching process, while atomic force microscopy characterization demonstrates improved post-etch surface smoothness, with a root mean square roughness of 0.204 nm. This work provides valuable insights into low damage gate trench etching for ScAlN-based devices.