Study of GaAs and GaInP etching in Cl2/Ar electron cyclotron resonance plasma

S. F. Yoon*, Tien Khee Ng, H. Q. Zheng

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

5 Scopus citations

Abstract

GaInP grown lattice-matched to GaAs is a very attractive material system for application in heterojunction bipolar transistors (HBTs) due to its superior properties over the AlGaAs/GaAs system. In this paper, the etching characteristics of GaAs and GaInP using electron cyclotron resonance (ECR) plasma are reported. The high-density low ion energy plasma characteristic is beneficial for low-damage material processing. It was found that the GaAs and GaInP sidewall profile and surface morphology was greatly affected by the Cl2/Ar flow rates, with near vertical sidewall profiles obtained at low Cl2 and Ar flow rates of 10 sccm. Furthermore, the GaInP surface characteristic was very sensitive to Ar flow rate, with grass-like features observed at a flow rate of 40 sccm. Such features were absent at an Ar flow rate of 10 sccm, suggesting that high Ar flow retarded the etching by-product desorption. Increasing the DC self-bias from |20| to |70| V resulted in change of the GaInP sidewall pro file from undercut to near-vertical characteristic along the (110) crystal plane. In the case of the GaInP/GaAs heterostructure, etching at |70| V DC self-bias results in a smoother GaAs surface after the top GaInP layer was etched. Optimised conditions for GaInP/GaAs heterostructure etching was established at Cl2/Ar 10:10 sccm, |70| V DC self-bias, 2.5 mtorr, 40°C and 200 W microwave power. The relatively slow etch rate of 7.2 nm/s gives good control for mesa etching in device fabrication processes. The resulting GaAs root-mean-square (RMS) surface roughness is 4 nm.

Original languageEnglish (US)
Pages (from-to)249-254
Number of pages6
JournalThin Solid Films
Volume394
Issue number1-2
StatePublished - Aug 15 2001

Keywords

  • Chlorine/argon etching
  • Electron cyclotron resonance plasma
  • Gallium arsenide
  • Gallium indium phosphide

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Surfaces and Interfaces
  • Surfaces, Coatings and Films
  • Metals and Alloys
  • Materials Chemistry

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