Ultradeep electron cyclotron resonance plasma etching of GaN
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 morph...
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Veröffentlicht in: | Journal of vacuum science & technology. A, Vacuum, surfaces, and films Vacuum, surfaces, and films, 2017-11, Vol.35 (6) |
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Sprache: | eng |
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Zusammenfassung: | 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. |
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ISSN: | 0734-2101 1520-8559 |
DOI: | 10.1116/1.4994829 |