ICP etching of GaN microstructures in a Cl2–Ar plasma with subnanometer-scale sidewall surface roughness

Frye, Clint D.; Reinhardt, Catherine E.; Donald, Scott B.; Voss, Lars F.; Harrison, Sara E.

doi:10.1016/j.mssp.2022.106564

Title: ICP etching of GaN microstructures in a Cl₂–Ar plasma with subnanometer-scale sidewall surface roughness

Journal Article · 18 February 2022 · Materials Science in Semiconductor Processing

DOI: https://doi.org/10.1016/j.mssp.2022.106564 · OSTI ID:1882279

^[1]; Reinhardt, Catherine E. ^[1];

^[1];

^[1]; Harrison, Sara E. ^[1]

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

In this work, substrate temperature, RF power, and ICP power were investigated for their effects on GaN micropillar sidewall roughness and etch characteristics. Elevated substrate temperature was shown to improve the sidewall etch morphology at low RF powers (reduced physical bombardment) and low ICP powers (lower plasma densities). Increased lateral etching is observed with both increased ICP power and substrate temperature, which both act to increase the chemical component of the etch. Etch conditions with a high chemical driving force resulted in faceting along the a-plane on the sidewalls. This faceting produced extremely smooth surfaces with root-meansquare roughness (R_q) as low as 0.20 nm which is comparable to typical epitaxy-ready surfaces and smaller than the a-plane lattice spacing of 0.3186 nm. The smooth surfaces produced in this study enable possibilities for laser facets or for new device structures that require high quality surfaces for GaN regrowth.

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Research Organization:: Lawrence Livermore National Laboratory (LLNL), Livermore, CA (United States)

Sponsoring Organization:: USDOE; USDOE Laboratory Directed Research and Development (LDRD) Program; USDOE National Nuclear Security Administration (NNSA)

Grant/Contract Number:: AC52-07NA27344

OSTI ID:: 1882279

Report Number(s):: LLNL-JRNL-822768; 1034914

Journal Information:: Materials Science in Semiconductor Processing, Journal Name: Materials Science in Semiconductor Processing Vol. 144; ISSN 1369-8001

Publisher:: ElsevierCopyright Statement

Country of Publication:: United States

Language:: English

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36 MATERIALS SCIENCE
42 ENGINEERING
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Gallium nitride
Plasma etching
Surface roughness
Wide bandgap

Title: ICP etching of GaN microstructures in a Cl2–Ar plasma with subnanometer-scale sidewall surface roughness

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References (36)

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Title: ICP etching of GaN microstructures in a Cl₂–Ar plasma with subnanometer-scale sidewall surface roughness