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Evaluation of Candidate Metals for Dual-Metal Gate CMOS with HfO2 Gate Dielectric

Published online by Cambridge University Press:  01 February 2011

S.B. Samavedam
Affiliation:
Motorola Digital DNA Laboratories, 3501 Ed Bluestein Blvd, MD:K10, Austin, TX 78721
J.K. Schaeffer
Affiliation:
Motorola Digital DNA Laboratories, 3501 Ed Bluestein Blvd, MD:K10, Austin, TX 78721
D.C. Gilmer
Affiliation:
Motorola Digital DNA Laboratories, 3501 Ed Bluestein Blvd, MD:K10, Austin, TX 78721
V. Dhandapani
Affiliation:
Motorola Digital DNA Laboratories, 3501 Ed Bluestein Blvd, MD:K10, Austin, TX 78721
P.J. Tobin
Affiliation:
Motorola Digital DNA Laboratories, 3501 Ed Bluestein Blvd, MD:K10, Austin, TX 78721
J. Mogab
Affiliation:
Motorola Digital DNA Laboratories, 3501 Ed Bluestein Blvd, MD:K10, Austin, TX 78721
B-Y. Nguyen
Affiliation:
Motorola Digital DNA Laboratories, 3501 Ed Bluestein Blvd, MD:K10, Austin, TX 78721
S. Dakshina-Murthy
Affiliation:
AMD-Motorola Alliance, 3501 Ed Bluestein Blvd, MD:K10, Austin, TX 78721
R.S. Rai
Affiliation:
Motorola Digital DNA Laboratories, 3501 Ed Bluestein Blvd, MD:K10, Austin, TX 78721
Z-X. Jiang
Affiliation:
Motorola Digital DNA Laboratories, 3501 Ed Bluestein Blvd, MD:K10, Austin, TX 78721
R. Martin
Affiliation:
Motorola Digital DNA Laboratories, 3501 Ed Bluestein Blvd, MD:K10, Austin, TX 78721
M.V. Raymond
Affiliation:
Motorola Digital DNA Laboratories, 3501 Ed Bluestein Blvd, MD:K10, Austin, TX 78721
M. Zavala
Affiliation:
Motorola Digital DNA Laboratories, 3501 Ed Bluestein Blvd, MD:K10, Austin, TX 78721
L.B. La
Affiliation:
Motorola Digital DNA Laboratories, 3501 Ed Bluestein Blvd, MD:K10, Austin, TX 78721
J.A. Smith
Affiliation:
Motorola Digital DNA Laboratories, 3501 Ed Bluestein Blvd, MD:K10, Austin, TX 78721
R.B. Gregory
Affiliation:
Motorola Digital DNA Laboratories, Mesa, AZ
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Abstract

As the MOSFET gate lengths are scaled down to 50 nm or below, the expected increase in gate leakage will be countered by the use of a high dielectric constant (high K) material. The series capacitance from polysilicon gate electrode depletion significantly reduces the gate capacitance as the dielectric thickness is scaled down to 10 Å equivalent oxide thickness (EOT) or below. Metal gates promise to solve this problem and address other problems like boron penetration and enhanced gate resistance that will have increased focus as the polysilicon gate thickness is reduced. Extensive simulations have shown that the optimal gate work-functions for the sub-50 nm channel lengths should be 0.2 eV below (above) the conduction (valence) band edge of silicon for n-MOSFETs (p-MOSFETs). This study summarizes the evaluations of TiN, TaSiN, WN, TaN, TaSi, Ir and IrO2 as candidate metals for dual-metal gate CMOS using HfO2 as the gate dielectric. The gate work-function was determined by fabricating MOS capacitors with varying dielectric thicknesses and different post-gate anneals. The metal-dielectric compatibility and thermal stability was studied by annealing the stacks at different temperatures. The gate stacks were characterized using TEM, SIMS and X-ray diffraction. Based on workfunctions and thermal stability, TaSiN and TaN show most promise as metal electrodes for HfO2 n-MOSFETs.

Type
Research Article
Copyright
Copyright © Materials Research Society 2002

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