Plasma enhanced atomic layer deposition and atomic layer etching of gallium oxide using trimethylgallium.

Atomic layer etching driven by self-limiting thermal reactions has recently been developed as a highly conformal and isotropic technique for low damage atomic scale material removal by sequential exposures of vapor phase reactants. Gallium oxide (Ga 2 O 3 ) is currently among the materials of interest due to a large variety of applications including power electronics, solar cells, gas sensors, and photon detectors. In this study, Ga 2 O 3 was deposited by plasma enhanced atomic layer deposition using trimethylgallium [TMG, Ga(CH 3 ) 3 ] and O 2 plasma at a substrate temperature of 200 °C. We report a newly developed method for Ga 2 O 3 thermal atomic layer etching, in which surface modification is achieved through HF exposure resulting in a gallium fluoride surface layer, and then removed through volatile product formation via ligand exchange with TMG. Saturation of the precursor exposure at a substrate temperature of 300 °C resulted in an etch rate of 1.0 ± 0.1 Å/cycle for amorphous Ga 2 O 3 . Uniformity and conformality of the atomic layer etching process were confirmed via atomic force microscopy with a measured surface roughness of 0.55 ± 0.05 nm that remains unchanged after etching. The use of TMG for etching may expand available precursors for atomic layer etching processes, while allowing for both etching and deposition of Ga 2 O 3 using the same metalorganic precursor. [ABSTRACT FROM AUTHOR]

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