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Aluminum Alloy Formation and Impacts in Advanced Replacement Metal Gate Process

Published online by Cambridge University Press:  31 January 2012

K. Xu
Affiliation:
Applied Materials, 974E. Arques Ave. Sunnyvale, CA 94085, U.S.A. E-mail: [email protected]
Y. Wang
Affiliation:
Applied Materials, 974E. Arques Ave. Sunnyvale, CA 94085, U.S.A. E-mail: [email protected]
S.H. Shen
Affiliation:
Applied Materials, 974E. Arques Ave. Sunnyvale, CA 94085, U.S.A. E-mail: [email protected]
X. Xia
Affiliation:
Applied Materials, 974E. Arques Ave. Sunnyvale, CA 94085, U.S.A. E-mail: [email protected]
W.Ch. Tu
Affiliation:
Applied Materials, 974E. Arques Ave. Sunnyvale, CA 94085, U.S.A. E-mail: [email protected]
L. Karuppiah
Affiliation:
Applied Materials, 974E. Arques Ave. Sunnyvale, CA 94085, U.S.A. E-mail: [email protected]
H. Yang
Affiliation:
Applied Materials, 974E. Arques Ave. Sunnyvale, CA 94085, U.S.A. E-mail: [email protected]
Z. Ge
Affiliation:
Applied Materials, 974E. Arques Ave. Sunnyvale, CA 94085, U.S.A. E-mail: [email protected]
Y. Lei
Affiliation:
Applied Materials, 974E. Arques Ave. Sunnyvale, CA 94085, U.S.A. E-mail: [email protected]
M. Allen
Affiliation:
Applied Materials, 974E. Arques Ave. Sunnyvale, CA 94085, U.S.A. E-mail: [email protected]
N. Yoshida
Affiliation:
Applied Materials, 974E. Arques Ave. Sunnyvale, CA 94085, U.S.A. E-mail: [email protected]
L.W. Chang
Affiliation:
Applied Materials, 974E. Arques Ave. Sunnyvale, CA 94085, U.S.A. E-mail: [email protected]
B. Liu
Affiliation:
Applied Materials, 974E. Arques Ave. Sunnyvale, CA 94085, U.S.A. E-mail: [email protected]
M. Okazaki
Affiliation:
Applied Materials, 974E. Arques Ave. Sunnyvale, CA 94085, U.S.A. E-mail: [email protected]
A. Brand
Affiliation:
Applied Materials, 974E. Arques Ave. Sunnyvale, CA 94085, U.S.A. E-mail: [email protected]
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Abstract

For the gate last approach of a high K metal gate scheme used in advanced CMOS technology, various materials were tested as wetting layers to allow Aluminum (Al) gap fill at gate widths of10 to 45 nanometers. In this study, Titanium (Ti) and Cobalt (Co) were investigated as a wetting layer for Al gap fill. It was discovered that Al-Ti and Al-Co alloys were formed during high temperature Al deposition. Alloys were characterized using XRD. Alloy’s impacts on line resistivity and subsequent Al Chemical Mechanical Polish (Al CMP) were also investigated. In addition, a model was established to predict the alloy type and alloy mole% with respect to feature size. The predicted Al mole% by this model correlated very well with 1) line resistivity trend and 2) morphologies. The model also predicted that due to Al lower electro-chemical potential than Ti, Co or its alloys, galvanic corrosion could take place depending on the chemical environment in the Al CMP slurry. Different slurry or cleaning chemical may reduce or increase the risk of galvanic corrosion. The knowledge gained with the help of the model provides clear directions on selection criteria for wetting layers, optimization for deposition processes and Al CMP consumable design to meet the challenges.

Keywords

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Articles
Copyright
Copyright © Materials Research Society 2012

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References

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