Title: Cu pumping in TSVs: Effect of pre-CMP thermal budget
Authors: De Wolf, Ingrid ×
Croes, K
Pedreira, O. Varela
Labie, R
Redolfi, A
Van De Peer, M
Vanstreels, K
Okoro, C
Vandevelde, B
Beynea, E #
Issue Date: Sep-2011
Publisher: Pergamon-elsevier science ltd
Series Title: Microelectronics Reliability vol:51 issue:9-11 pages:1856-1859
Abstract: When Cu 'Through-Silicon-Vias' (TSVs) are exposed to high temperatures as typically encountered during the back-end of line (BEOL) processing, the higher coefficient of thermal expansion (CTE) of Cu forces it to expand more than Si. This causes compressive stress in the confined Cu inside the TSV. This stress can partly be released near the top of the TSV, by out-of-plane expansion of the Cu, the so-called 'Cu pumping'. It can severely damage the BEOL layers. In this paper the effect of a pre-CMP thermal budget (temperature and time) on Cu pumping is studied for various Cu chemistries and TSV aspect ratios. It is shown that to suppress Cu pumping a pre-CMP anneal is required that is either very long or at a temperature very close to the maximum temperature used in the BEOL processing. (C) 2011 Elsevier Ltd. All rights reserved.
ISSN: 0026-2714
Publication status: published
KU Leuven publication type: IT
Appears in Collections:Department of Materials Engineering - miscellaneous
× corresponding author
# (joint) last author

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