【Epitaxy Papers】Atomic Layer Etching of Ga₂O₃ using SF₆/BCl₃ Chemistry: Achieving Atomic-Scale Precision and Damage-Free Surface Preservation

      Researchers from the Shanghai University have published a dissertation titled "Atomic Layer Etching of Ga₂O₃ using SF₆/BCl₃ Chemistry: Achieving Atomic-Scale Precision and Damage-Free Surface Preservation" in 2025 22nd China International Forum on Solid State Lighting & 2025 11th International Forum on Wide Bandgap Semiconductors (SSLCHINA: IFWS).

Abstract

      Atomic layer etching (ALE) based on sequential, selflimiting half-reactions is employed to achieve angstrom-scale, low-damage removal in ultrawide-bandgap oxides. ALE of β-Ga₂O₃ is demonstrated using a dose-separated SF₆/BCl₃ sequence, in which SF₆ fluorination forms an ultrathin Ga-F termination that is subsequently removed by BCl₃-enabled ligand exchange to volatile GaCl_x. Under saturated exposures of both precursors at 20°C, the etch per cycle (EPC) is 0.101 nm/ cycle. Isotropic, surface-limited removal with pronounced surface smoothing is obtained with the SF₆/BCl₃ sequence. A reduction in RMS surface roughness from 0.514 nm to 0.16 ± 0.05 nm after ALE is measured by atomic force microscopy, and this value is lower than that obtained with a comparable Cl₂-based plasma process. Self-limiting behavior at nearambient temperature is verified, and minimal surface damage is inferred. The precursor selection for Ga₂O₃ ALE is expanded by the successful use of SF₆, and a reliable, chemically uniform alternative to ion-bombardmentdominated plasma etches is thereby highlighted for device fabrication flows in which surface degradation, roughnessinduced scattering, and 3D non-uniformity are critical concerns.

DOI：

https://doi.org/10.1109/SSLCHINAIFWS69008.2025.11315027