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A Selective Etching Process for Chemically Inert High-k Metal Oxides

Published online by Cambridge University Press:  11 February 2011

Katherine L. Saenger,
Harald F. Okorn-Schmidt and
Christopher P. D'Emic
Katherine L. Saenger
Affiliation:
IBM Research Division, T.J. Watson Research Center, Yorktown Heights, NY 10598, U.S.A.
Harald F. Okorn-Schmidt
Affiliation:
IBM Research Division, T.J. Watson Research Center, Yorktown Heights, NY 10598, U.S.A.
Christopher P. D'Emic
Affiliation:
IBM Research Division, T.J. Watson Research Center, Yorktown Heights, NY 10598, U.S.A.
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Abstract

Once annealed, high-k metal oxides such as HfO2 and Al2O3 can be extremely difficult to etch by wet chemical methods. Here we describe how ion bombardment at relatively low energy (a few hundred eV) can be used to make exposed regions of annealed HfO2 films etchable in aqueous HF-based solutions. HfO2 layers, 2–5 nm in thickness, were deposited by atomic layer chemical vapor deposition (ALCVD) on Si substrates, annealed at 700 °C, and subjected to selected-area ion bombardment supplied by an oxygen plasma in a reactive ion etching tool. Etch times (as indicated by time to “dewet“) were examined as a function of HfO2 thickness, the power and time of oxygen plasma treatments, post-oxygen-plasma anneals, and wet etch chemistry. Strategies for etching thicker films and additional data provided by electrochemical open circuit potential (OCP) measurements will also be discussed.

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References

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