Work function tuning of plasma-enhanced atomic layer deposited WCxNy electrodes for metal/oxide/semiconductor devices

One of the main challenges facing the integration of metals as gate electrodes in advanced MOS devices is control over the Fermi level position at the metal/dielectric interface. In this study, we demonstrate the ability to tune the effective work function (EWF) of W-based electrodes by process modi...

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Bibliographic Details
Published in:Applied physics letters 2015-02, Vol.106 (8)
Main Authors: Zonensain, Oren, Fadida, Sivan, Fisher, Ilanit, Gao, Juwen, Chattopadhyay, Kaushik, Harm, Greg, Mountsier, Tom, Danek, Michal, Eizenberg, Moshe
Format: Article
Language:English
Subjects:
Applied physics
Atomic layer epitaxy
Chemical bonds
Electrodes
Hydrogen plasma
Metal oxide semiconductors
MOS devices
Nitrogen
Organic chemistry
Plasma
Semiconductor devices
Stoichiometry
Tungsten carbide
Work functions
X ray spectra
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Summary:One of the main challenges facing the integration of metals as gate electrodes in advanced MOS devices is control over the Fermi level position at the metal/dielectric interface. In this study, we demonstrate the ability to tune the effective work function (EWF) of W-based electrodes by process modifications of the atomic layer deposited (ALD) films. Tungsten carbo-nitrides (WCxNy) films were deposited via plasma-enhanced and/or thermal ALD processes using organometallic precursors. The process modifications enabled us to control the stoichiometry of the WCxNy films. Deposition in hydrogen plasma (without nitrogen based reactant) resulted in a stoichiometry of WC0.4 with primarily W-C chemical bonding, as determined by x-ray photoelectron spectroscopy. These films yielded a relatively low EWF of 4.2 ± 0.1 eV. The introduction of nitrogen based reactant to the plasma or the thermal ALD deposition resulted in a stoichiometry of WC0.1N0.6–0.8 with predominantly W-N chemical bonding. These films produced a high EWF of 4.7 ± 0.1 eV.
ISSN:0003-6951
1077-3118
DOI:10.1063/1.4913715