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Low Temperature Direct Cu-Cu Immersion Bonding for 3D Integration

Published online by Cambridge University Press:  31 January 2011

Rahul Agarwal and
Wouter Ruythooren
Rahul Agarwal
Affiliation:
rahul.agarwal@imec.be, IMEC, Interconnect and Packaging, Heverlee, Belgium
Wouter Ruythooren
Affiliation:
Wouter.Ruythooren@imec.be, IMEC, Wet processing Epi Assembly, Heverlee, Belgium
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Abstract

High yielding and high strength Cu-Cu thermo-compression bonds have been obtained at temperatures as low as 175°C. Plated Cu bumps are used for bonding, without any surface planarization step or plasma treatment, and bonding is performed at atmospheric condition. In this work the 25μm diameter bumps are used at a bump pitch of 100μm and 40μm. Low temperature bonding is achieved by using immersion bonding in citric acid. Citric acid provides in-situ cleaning of the Cu surface during the bonding process. The daisy chain electrical bonding yield ranges from 84%-100% depending on the bonding temperature and pressure.

Keywords

bondingCupackaging

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