Ultradeep electron cyclotron resonance plasma etching of GaN

Journal Article · 25 July 2017 · Journal of Vacuum Science and Technology A

DOI: https://doi.org/10.1116/1.4994829 · OSTI ID:1389946

Harrison, Sara E. ^[1]; Voss, Lars F. ^[1]; Torres, Andrea M. ^[1]; Frye, Clint D. ^[1]; Shao, Qinghui ^[1]; Nikolic, Rebecca J. ^[1]

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1. Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

Here, ultradeep (≥5 μm) electron cyclotron resonance plasma etching of GaN micropillars was investigated. Parametric studies on the influence of the applied radio-frequency power, chlorine content in a Cl₂/Ar etch plasma, and operating pressure on the etch depth, GaN-to-SiO₂ selectivity, and surface morphology were performed. Etch depths of >10 μm were achieved over a wide range of parameters. Etch rates and sidewall roughness were found to be most sensitive to variations in RF power and % Cl₂ in the etch plasma. Selectivities of >20:1 GaN:SiO₂ were achieved under several chemically driven etch conditions where a maximum selectivity of ~39:1 was obtained using a 100% Cl₂ plasma. The etch profile and (0001) surface morphology were significantly influenced by operating pressure and the chlorine content in the plasma. Optimized etch conditions yielded >10 μm tall micropillars with nanometer-scale sidewall roughness, high GaN:SiO₂ selectivity, and nearly vertical etch profiles. These results provide a promising route for the fabrication of ultradeep GaN microstructures for use in electronic and optoelectronic device applications. In addition, dry etch induced preferential crystallographic etching in GaN microstructures is also demonstrated, which may be of great interest for applications requiring access to non- or semipolar GaN surfaces.

• Research Organization: Lawrence Livermore National Laboratory (LLNL), Livermore, CA (United States)
• Sponsoring Organization: USDOE
• Grant/Contract Number: AC52-07NA27344
• OSTI ID: 1389946
• Report Number(s): LLNL-JRNL--730843
• Journal Information: Journal of Vacuum Science and Technology A, Journal Name: Journal of Vacuum Science and Technology A Journal Issue: 6 Vol. 35; ISSN 0734-2101
• Publisher: American Vacuum SocietyCopyright Statement
• Country of Publication: United States
• Language: English