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Elastic anisotropy of Cu and its impact on stress management for 3D IC: Nanoindentation and TCAD simulation study

Published online by Cambridge University Press:  21 October 2011

Kong Boon Yeap*
Affiliation:
Fraunhofer Institute for Nondestructive Testing, 01109 Dresden, Germany
Ehrenfried Zschech
Affiliation:
Fraunhofer Institute for Nondestructive Testing, 01109 Dresden, Germany
Ude D. Hangen
Affiliation:
Hysitron Inc., Minneapolis, Minnesota 55344
Thomas Wyrobek
Affiliation:
Hysitron Inc., Minneapolis, Minnesota 55344
Lay Wai Kong
Affiliation:
State University of New York, College of Nanoscale Science and Engineering, Albany, New York 12203
Aditya Karmakar
Affiliation:
Synopsys Inc., Mountain View, California 94043
Xiaopeng Xu
Affiliation:
Synopsys Inc., Mountain View, California 94043
Iuliana Panchenko
Affiliation:
Technische Universitaet Dresden, Electronics Packaging Laboratory, 01069 Dresden, Germany
*
a)Address all correspondence to this author. e-mail: KongBoon.Yeap@izfp-d.fraunhofer.de
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Abstract

This article presents a study on elastic anisotropy of Cu by indentations at different penetration depth ranges (sub-10 nm, several-10 nm, and several-100 nm), and the impact of elastic anisotropy on the stress in 3D stacked integrated circuits (3D ICs). The reduced modulus, ER, values determined at sub-10 nm indentations on Cu single crystals are very close to the unidirectional values. Similarly, cross-sectional sub-10 nm indentation tests on the Cu grains in a through-silicon via (TSV) show unidirectional ER values. In contrast, the Hill’s average values are observed at several-100 nm indentations. We propose that before lattice rotation happens within a volume beneath the indentation, elastic anisotropy can be strongly reflected in the ER value. When the experimentally measured Cu elastic anisotropy is used in a technology computer-aided design simulation of a Cu-filled TSV, significant impacts are observed on the stress field and the carrier mobility variation in an active Si region.

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Articles
Copyright
Copyright © Materials Research Society 2011

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