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Group-III Nitride Etch Selectivity in BCl3/Cl2 ICP Plasmas

Published online by Cambridge University Press:  15 February 2011

R. J. Shul
Affiliation:
Sandia National Laboratories, Albuquerque, NM 87185-0603, rjshul@sandia.gov
L. Zhang
Affiliation:
Sandia National Laboratories, Albuquerque, NM 87185-0603, rjshul@sandia.gov
C. G. Willison
Affiliation:
Sandia National Laboratories, Albuquerque, NM 87185-0603, rjshul@sandia.gov
J. Han
Affiliation:
Sandia National Laboratories, Albuquerque, NM 87185-0603, rjshul@sandia.gov
S. J. Pearton
Affiliation:
University of Florida, Department of Materials Science and Engineering, Gainesville, FL 32611
J. Hong
Affiliation:
University of Florida, Department of Materials Science and Engineering, Gainesville, FL 32611
C. R. Abernathy
Affiliation:
University of Florida, Department of Materials Science and Engineering, Gainesville, FL 32611
L. F. Lester
Affiliation:
University of New Mexico, Electrical Engineering, Albuquerque, NM
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Abstract

Patterning the group-III nitrides has been challenging due to their strong bond energies and relatively inert chemical nature as compared to other compound semiconductors. Plasma etch processes have been used almost exclusively to pattern these films. The use of high-density plasma etch systems, including inductively coupled plasmas (ICP), has resulted in relatively high etch rates (often greater than 1.0 μm/min) with anisotropic profiles and smooth etch morphologies. However, the etch mechanism is often dominated by high ion bombardment energies which can minimize etch selectivity. The use of an ICP-generated BCl3/Cl2 plasma has yielded a highly versatile GaN etch process with rates ranging from 100 to 8000 Å/min making this plasma chemistry a prime candidate for optimization of etch selectivity. In this study, we will report ICP etch rates and selectivities for GaN, AIN, and InN as a function of BCl3/C12 flow ratios, cathode rf-power, and ICP-source power. GaN:InN and GaN:AIN etch selectivities were typically less than 7:1 and showed the strongest dependence on flow ratio. This trend may be attributed to faster GaN etch rates observed at higher concentrations of atomic Cl which was monitored using optical emission spectroscopy (OES).

Type
Research Article
Copyright
Copyright © Materials Research Society 1999

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