Polarity dependence in Cl2-based plasma etching of GaN, AlGaN and AlN

Matthew D. Smith; Xu Li; Michael J. Uren; Iain G. Thayne; Martin Kuball

doi:10.1016/j.apsusc.2020.146297

Polarity dependence in Cl₂-based plasma etching of GaN, AlGaN and AlN

Matthew D. Smith
, Xu Li
, Michael J. Uren
, Iain G. Thayne
, Martin Kuball^*

^*Corresponding author for this work

School of Physics

Research output: Contribution to journal › Article (Academic Journal) › peer-review

10 Citations (Scopus)

Abstract

This work compares Cl₂-based inductively-coupled plasma (ICP) etching of N-polar and III-polar Al_xGa_1-xN, including GaN and AlN. For the etch processes of this study, etch rates of Al_xGa_1-xN decreased with increasing Al:Ga alloy ratio. A 750 W ICP power, 175 W platen power Cl₂/Ar ICP process exhibited etch rates in the range 160–450 nm/min for Al_xGa_1-xN with the precise rate depending on alloy composition and material polarity, and etch rate selectivity between AlN and GaN of 3.0 for III-polar material and 1.6 for N-polar material. Cl₂/Ar/O₂ processes with 650 W ICP power and 50 W platen power showed an overall reduction in etch rate in the range 2–360 nm/min for Al_xGa_1-xN with precise rate depending on alloy composition and material polarity. These O₂ containing chemistries demonstrated significantly greater etch rate selectivity for N-polar materials (8–80) compared to III-polar materials (1.8–1.9). A correlation between GaN etch rate, surface roughening and selectivity was observed, and the possible reasons behind the polarity dependence of etch rate selectivity are discussed.

Original language	English
Article number	146297
Journal	Applied Surface Science
Volume	521
DOIs	https://doi.org/10.1016/j.apsusc.2020.146297
Publication status	Published - 20 Apr 2020

Bibliographical note

Funding Information:
This work was supported by the Engineering and Physical Sciences Research Council (EPSRC) Grant GaN-DaME (EP/P00945X/1) .

Publisher Copyright:
© 2020 Elsevier B.V.

Copyright:
Copyright 2020 Elsevier B.V., All rights reserved.

Keywords

Etching
GaN
Plasma
Polarity
Selective
Semiconductors

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Cite this

@article{02b86ae0c16240969ebdbd8feb5fed06,

title = "Polarity dependence in Cl2-based plasma etching of GaN, AlGaN and AlN",

abstract = "This work compares Cl2-based inductively-coupled plasma (ICP) etching of N-polar and III-polar AlxGa1-xN, including GaN and AlN. For the etch processes of this study, etch rates of AlxGa1-xN decreased with increasing Al:Ga alloy ratio. A 750 W ICP power, 175 W platen power Cl2/Ar ICP process exhibited etch rates in the range 160–450 nm/min for AlxGa1-xN with the precise rate depending on alloy composition and material polarity, and etch rate selectivity between AlN and GaN of 3.0 for III-polar material and 1.6 for N-polar material. Cl2/Ar/O2 processes with 650 W ICP power and 50 W platen power showed an overall reduction in etch rate in the range 2–360 nm/min for AlxGa1-xN with precise rate depending on alloy composition and material polarity. These O2 containing chemistries demonstrated significantly greater etch rate selectivity for N-polar materials (8–80) compared to III-polar materials (1.8–1.9). A correlation between GaN etch rate, surface roughening and selectivity was observed, and the possible reasons behind the polarity dependence of etch rate selectivity are discussed.",

keywords = "Etching, GaN, Plasma, Polarity, Selective, Semiconductors",

author = "Smith, \{Matthew D.\} and Xu Li and Uren, \{Michael J.\} and Thayne, \{Iain G.\} and Martin Kuball",

note = "Funding Information: This work was supported by the Engineering and Physical Sciences Research Council (EPSRC) Grant GaN-DaME (EP/P00945X/1) . Publisher Copyright: {\textcopyright} 2020 Elsevier B.V. Copyright: Copyright 2020 Elsevier B.V., All rights reserved.",

year = "2020",

month = apr,

day = "20",

doi = "10.1016/j.apsusc.2020.146297",

language = "English",

volume = "521",

journal = "Applied Surface Science",

issn = "0169-4332",

publisher = "Elsevier B.V.",

}

TY - JOUR

T1 - Polarity dependence in Cl2-based plasma etching of GaN, AlGaN and AlN

AU - Smith, Matthew D.

AU - Li, Xu

AU - Uren, Michael J.

AU - Thayne, Iain G.

AU - Kuball, Martin

N1 - Funding Information: This work was supported by the Engineering and Physical Sciences Research Council (EPSRC) Grant GaN-DaME (EP/P00945X/1) . Publisher Copyright: © 2020 Elsevier B.V. Copyright: Copyright 2020 Elsevier B.V., All rights reserved.

PY - 2020/4/20

Y1 - 2020/4/20

N2 - This work compares Cl2-based inductively-coupled plasma (ICP) etching of N-polar and III-polar AlxGa1-xN, including GaN and AlN. For the etch processes of this study, etch rates of AlxGa1-xN decreased with increasing Al:Ga alloy ratio. A 750 W ICP power, 175 W platen power Cl2/Ar ICP process exhibited etch rates in the range 160–450 nm/min for AlxGa1-xN with the precise rate depending on alloy composition and material polarity, and etch rate selectivity between AlN and GaN of 3.0 for III-polar material and 1.6 for N-polar material. Cl2/Ar/O2 processes with 650 W ICP power and 50 W platen power showed an overall reduction in etch rate in the range 2–360 nm/min for AlxGa1-xN with precise rate depending on alloy composition and material polarity. These O2 containing chemistries demonstrated significantly greater etch rate selectivity for N-polar materials (8–80) compared to III-polar materials (1.8–1.9). A correlation between GaN etch rate, surface roughening and selectivity was observed, and the possible reasons behind the polarity dependence of etch rate selectivity are discussed.

AB - This work compares Cl2-based inductively-coupled plasma (ICP) etching of N-polar and III-polar AlxGa1-xN, including GaN and AlN. For the etch processes of this study, etch rates of AlxGa1-xN decreased with increasing Al:Ga alloy ratio. A 750 W ICP power, 175 W platen power Cl2/Ar ICP process exhibited etch rates in the range 160–450 nm/min for AlxGa1-xN with the precise rate depending on alloy composition and material polarity, and etch rate selectivity between AlN and GaN of 3.0 for III-polar material and 1.6 for N-polar material. Cl2/Ar/O2 processes with 650 W ICP power and 50 W platen power showed an overall reduction in etch rate in the range 2–360 nm/min for AlxGa1-xN with precise rate depending on alloy composition and material polarity. These O2 containing chemistries demonstrated significantly greater etch rate selectivity for N-polar materials (8–80) compared to III-polar materials (1.8–1.9). A correlation between GaN etch rate, surface roughening and selectivity was observed, and the possible reasons behind the polarity dependence of etch rate selectivity are discussed.

KW - Etching

KW - GaN

KW - Plasma

KW - Polarity

KW - Selective

KW - Semiconductors

UR - https://www.scopus.com/pages/publications/85083593155

U2 - 10.1016/j.apsusc.2020.146297

DO - 10.1016/j.apsusc.2020.146297

M3 - Article (Academic Journal)

AN - SCOPUS:85083593155

SN - 0169-4332

VL - 521

JO - Applied Surface Science

JF - Applied Surface Science

M1 - 146297

ER -

Polarity dependence in Cl₂-based plasma etching of GaN, AlGaN and AlN

Abstract

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Integrated GaN-Diamond Microwave Electronics: From Materials, Transistors to MMICs - 'GaN-DaME'

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Polarity dependence in Cl2-based plasma etching of GaN, AlGaN and AlN

Abstract

Bibliographical note

Keywords

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Integrated GaN-Diamond Microwave Electronics: From Materials, Transistors to MMICs - 'GaN-DaME'

Cite this

Polarity dependence in Cl₂-based plasma etching of GaN, AlGaN and AlN