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Tunable Workfunction with TaN Metal Gate on HfO2-HfxSiyO Dielectrics

Published online by Cambridge University Press:  28 July 2011

Christopher S. Olsen
Affiliation:
Applied Materials, Sunnyvale, CA 94086 USA Ching-Huang Lu, Michael Deal, Yoshio Nishi Center for Integrated Systems,Standford University, Palo Alto, CA 94306, USA
Philip A. Kraus
Affiliation:
Applied Materials, Sunnyvale, CA 94086 USA Ching-Huang Lu, Michael Deal, Yoshio Nishi Center for Integrated Systems,Standford University, Palo Alto, CA 94306, USA
Khaled Z. Ahmed
Affiliation:
Applied Materials, Sunnyvale, CA 94086 USA Ching-Huang Lu, Michael Deal, Yoshio Nishi Center for Integrated Systems,Standford University, Palo Alto, CA 94306, USA
Shreyas Kher
Affiliation:
Applied Materials, Sunnyvale, CA 94086 USA Ching-Huang Lu, Michael Deal, Yoshio Nishi Center for Integrated Systems,Standford University, Palo Alto, CA 94306, USA
Steven Hung
Affiliation:
Applied Materials, Sunnyvale, CA 94086 USA Ching-Huang Lu, Michael Deal, Yoshio Nishi Center for Integrated Systems,Standford University, Palo Alto, CA 94306, USA
Nety Krishna
Affiliation:
Applied Materials, Sunnyvale, CA 94086 USA Ching-Huang Lu, Michael Deal, Yoshio Nishi Center for Integrated Systems,Standford University, Palo Alto, CA 94306, USA
Jeff Chen
Affiliation:
Applied Materials, Sunnyvale, CA 94086 USA Ching-Huang Lu, Michael Deal, Yoshio Nishi Center for Integrated Systems,Standford University, Palo Alto, CA 94306, USA
Lucien Date
Affiliation:
Applied Materials, Sunnyvale, CA 94086 USA Ching-Huang Lu, Michael Deal, Yoshio Nishi Center for Integrated Systems,Standford University, Palo Alto, CA 94306, USA
Marc Burey
Affiliation:
Applied Materials, Sunnyvale, CA 94086 USA Ching-Huang Lu, Michael Deal, Yoshio Nishi Center for Integrated Systems,Standford University, Palo Alto, CA 94306, USA
Jason Campbell
Affiliation:
Applied Materials, Sunnyvale, CA 94086 USA Ching-Huang Lu, Michael Deal, Yoshio Nishi Center for Integrated Systems,Standford University, Palo Alto, CA 94306, USA
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Abstract

MOS capacitors were fabricated from MOCVD HfO2 and HfxSiyO gate dielectrics with ALD TaN / PVD Ta metal electrodes. Dielectrics with 1.8 to 2.6 nm capacitance equivalent thickness (CET) were investigated with gate leakage (Jg) of 1×10−7 to 1×10−3 A/cm2 at Vg = Vfb−1V in accumulation. In addition to the C-V and I-V characterization of the MOSCAPs, XPS physical characterization was performed on monitor wafers to determine composition and physical thickness. From the combined results of the electrical and physical characterization, the relative dielectric constants of the Hf-Si-O films and the metal electrode work functions are determined, and simple models for the compositional dependence of the dielectric constant are formulated. Capacitors with the same dielectric composition and thickness exhibited 100 mV Vfb change when the thickness of the ALD TaN electrode layer was changed from 40-80Å. This change is attributed to a change in the work function of the aggregate TaN / Ta metal electrode. Workfunctions were found to be located near middle of the Si band gap, with workfunctions of 4.6 eV to 4.7 eV.

Type
Research Article
Copyright
Copyright © Materials Research Society 2004

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