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Journal of Vacuum Science & Technology A / Volume 30 / Issue 2 / Letters

J. Vac. Sci. Technol. A 30, 020602 (2012); http://dx.doi.org/10.1116/1.3679551 (6 pages)

SiCl4/Cl2 plasmas: A new chemistry to etch high-k materials selectively to Si-based materials

Paul Bodart1, Gilles Cunge1, Olivier Joubert1, and Thorsten Lill2

1CNRS-LTM, 17, rue des martyrs, 38054 Grenoble Cedex, France
2Applied Materials Inc., 974E Arques Avenue, Sunnyvale, California 95085

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(Published online 1 February 2012)

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Plasma etching of ultrathin layers of high-k materials is one critical step in the fabrication of gate transistors. The main challenge in this process is to achieve an infinite etching selectively between the high-k and the Si (or SiO2 covered silicon) substrate to prevent damaging the source and drain regions of the transistor. State of the art high-k etching plasmas use BCl3 chemistries, sometime at high wafer temperature. However, the process window in which an infinite high-k/Si selectivity can be achieved is very narrow and several issues remain associated with these processes. In this work, we introduced a new high-k plasma etching chemistry: SiCl4/Cl2. It can be used to etch Hf-based and Al-based high-k materials with an infinite selectivity towards Si, SiO2 and SiON, and with a much wider process window than BCl3 plasmas. XPS analyses indicate that the selectivity mechanism relies on the formation of a SiClx deposit selectively on Si-containing materials, which prevent them from being etched. By contrast SiClx radicals and ions are directly involved in the etching of the metallic oxide layer by forming volatile products (most probably SiOClx and HfClx). This new chemistry may replace valuably BCl3-based plasmas for future high-k etching processes and it may also be interesting for other applications.

© 2012 American Vacuum Society

ACKNOWLEDGMENTS

We would like to acknowledge Camille Petit-Etienne and Sébastien Barnola and Latifa Desvoivres for their help in the course of these experiments and for providing the pattern wafers, respectively.

Article Outline

  1. INTRODUCTION
  2. EXPERIMENTAL SET UP
  3. RESULTS AND DISCUSSION
  4. SUMMARY AND CONCLUSIONS

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KEYWORDS and PACS

Keywords

elemental semiconductors, hafnium compounds, high-k dielectric thin films, silicon, silicon compounds, sputter etching, transistors, X-ray photoelectron spectra

PACS

  • 81.65.Cf

    Surface cleaning, etching, patterning

  • 77.55.D-

    High-permittivity gate dielectric films

  • 78.66.Db

    Elemental semiconductors and insulators

  • 79.60.-i

    Photoemission and photoelectron spectra

History
Received 1 December 2011
Accepted 7 January 2012
Published online 1 February 2012
Digital Object Identifier
http://dx.doi.org/10.1116/1.3679551

PUBLICATION DATA

ISSN

0734-2101 (print)  
1520-8559 (online)

Publisher

American Vacuum Society

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