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Comparison of Valence-Band Tunneling in Pure SiO2, Composite SiO2 /Ta2O5, and Pure Ta2O5, in Mosfets with 1.0 nm-Thick SiO2-Equivalent Gate Dielectrics

Published online by Cambridge University Press:  10 February 2011

A. Shanware
Affiliation:
Department of Electrical and Computer Engineering, Duke University, Durham, NC, 27708-0291
H. Z. Massoud
Affiliation:
Department of Electrical and Computer Engineering, Duke University, Durham, NC, 27708-0291
E. Vogel
Affiliation:
Department of Electrical and Computer Engineering, North Carolina State University, Raleigh, NC, 27695
K. Henson
Affiliation:
Department of Electrical and Computer Engineering, North Carolina State University, Raleigh, NC, 27695
J. R. Hauser
Affiliation:
Department of Electrical and Computer Engineering, North Carolina State University, Raleigh, NC, 27695
J. J. Wortman
Affiliation:
Department of Electrical and Computer Engineering, North Carolina State University, Raleigh, NC, 27695
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Abstract

The gate tunneling current in ultrathin gate dielectric NMOSFETs with positive gate bias is due to the tunneling of electrons from the conduction and valence bands of the substrate. Valence-band electrons tunnel from the substrate of NMOS devices when the valence-band edge in the substrate rises above the conduction-band edge in the substrate. This paper reports experimental trends in the contribution of valence-band electrons tunneling to the gate current of NMOSFETs with gate oxides composed of pure SiO2. The large gate tunneling current can be reduced by replacing the conventional SiO2 gate dielectric with alternative dielectrics with larger dielectric constants. This paper reports the effect of replacing SiO2 with alternative dielectrics on the contribution of valence-band electron tunneling to the gate current. Simulations are carried out for composite SiO2/Ta2O5 gate dielectric structures.

Type
Research Article
Copyright
Copyright © Materials Research Society 1999

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References

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