Sains Malaysiana 40(1)(2011): 78–82

ICP-RIE Dry Etching Using Cl₂-based on GaN

(Punaran Kering ICP-RIE Berasaskan-Cl₂ pada GaN)

Siti Azlina Rosli*, Azlan Abdul Aziz & Md Roslan Hashim

Nano Optoelectronics Research and Technology Laboratory

School of Physics, Universiti Sains Malaysia

11800 Minden, Pulau Pinang, Malaysia

Received: 7 December 2009 / Accepted: 22 July 2010

ABSTRACT

In this study, the plasma characteristics and GaN etch properties of inductively coupled Cl₂/Ar and Cl₂/H₂ plasmas were investigated. Our results showed that inductively coupled plasma (ICP) etching of gallium nitride by using Cl₂/Ar and Cl₂/H₂ were possible to meet the requirements (anisotropy, high etch rate and high selectivity). We have investigated the etching rate dependency on the percentage of argon and hydrogen in the gas mixture and the DC voltage. Surface morphology of the etched samples was checked by SEM and AFM. It was found that the etched surface was anisotropic and the smoothness of the etched surface is comparable to that of polished wafer. As results, gas mixture using Cl₂/Ar, we obtained highest etching rates; 5000 Å/min and ~0.5 nm rms roughness for n-GaN and for p-GaN, the etching rates was 3300 Å/min and ~0.7 nm for rms roughness. Meanwhile, for gas mixture using Cl₂/H₂, the etching was 1580 Å/min for n-GaN and 950 Å/min for p-GaN.

Keywords: Argon; gallium nitride; hydrogen; inductively coupled plasma etching

ABSTRAK

Dalam kajian ini, pencirian plasma dan kandungan punaran GaN pada gandingan teraruh plasma Cl₂/Ar dan Cl₂/H₂ telah dikaji. Kajian menunjukkan punaran plasma yang digandingkan secara teraruh (ICP) pada GaN menggunakan Cl₂/Ar dan Cl₂/H₂ akan menunjukkan keadaan yang anisotropik dengan kadar punaran dan peratusan kepilihan yang tinggi. Kadar punaran juga bergantung kepada peratusan argon dan hidrogen dalam campuran gas dan voltan DC. Morfologi permukaan pada sampel yang dipunar ditentukan menggunakan SEM dan AFM. Hasil menunjukkan bahawa permukaan GaN yang dipunar adalah anisotropik dan licin. Bagi campuran gas Cl₂/Ar, permukaan n-GaN memberikan kadar punaran tertinggi iaitu 5000 Å/min dan purata kekasaran ~0.5 nm. Manakala bagi permukaan p-GaN, kadar punaran tertinggi adalah 3300 Å/min dengan purata kekasaran ~0.7 nm. Bagi campuran gas Cl₂/H₂ pula, kadar punaran tertinggi adalah 1580 Å/min bagi permukaan n-GaN dan 950 Å/min bagi permukaan p-GaN.

Kata kunci: Argon; galium nitrida; hidrogen; punaran plasma digandingkan secara teraruh

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*Corresponding author; email:sazlina.zm05@student.usm.my, lan@usm.my