【Device Papers】Dry Etching of Cr₂MnO₄ Thin Films for Forming p-n Junctions with β-Ga₂O₃

      Researchers from the University of Florida have published a dissertation titled "Dry Etching of Cr₂MnO₄ Thin Films for Forming p-n Junctions with β-Ga₂O₃" in ECS Journal of Solid State Science and Technology.

Abstract

      We report the dry etching characteristics of Cr₂MnO₄ thin films using Cl₂-based inductively coupled plasmas (ICP) for applications in Ga₂O₃-based power electronics, where p-n heterojunctions offer advantages over Schottky diodes. Cr₂MnO₄, a thermally stable p-type oxide, was deposited via RF sputter beam epitaxy and etched using Cl₂/Ar and BCl₃/Ar plasmas, with the latter producing much lower etch rates. The etch rates and surface roughness were investigated as functions of Cl₂ flow rate, RF power, and gas composition. Results reveal that increasing the Cl₂ flow rate enhances etch rates but degrades surface roughness due to non-volatile chloride formation and redeposition. Higher RF power improves surface smoothness by increasing ion bombardment energy, promoting physical sputtering, and enabling uniform etching. The etch process is ion-flux limited, with threshold energies comparable to NiO. Post-etch X-ray photoelectron spectroscopy analysis confirms that NH₄OH rinsing effectively removes chlorine residues by dissolving metal chlorides and neutralizing acidic species, ensuring a clean surface. These findings underscore the importance of optimizing plasma parameters and post-etch cleaning for fabricating high-quality Cr₂MnO₄/Ga₂O₃ heterojunctions, which hold promise for high-temperature, high-power electronic applications.

DOI：

https://doi.org/10.1149/2162-8777/ade8a7