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Effect of passivation on stress relaxation in electroplated copper films

Published online by Cambridge University Press:  01 June 2006

Dongwen Gan ,
Paul S. Ho ,
Yaoyu Pang ,
Rui Huang ,
Jihperng Leu ,
Jose Maiz  and
Tracey Scherban
Dongwen Gan
Affiliation:
Laboratory for Interconnect and Packaging, University of Texas, Austin, Texas 78712
Paul S. Ho
Affiliation:
Laboratory for Interconnect and Packaging, University of Texas, Austin, Texas 78712
Yaoyu Pang
Affiliation:
Department of Aerospace Engineering and Engineering Mechanics, University of Texas, Austin, Texas 78712
Rui Huang*
Affiliation:
Department of Aerospace Engineering and Engineering Mechanics, University of Texas, Austin, Texas 78712
Jihperng Leu
Affiliation:
Intel Corporation, Hillsboro, Oregon 97214
Jose Maiz
Affiliation:
Intel Corporation, Hillsboro, Oregon 97214
Tracey Scherban
Affiliation:
Intel Corporation, Hillsboro, Oregon 97214
*
a) Address all correspondence to this author. e-mail: ruihuang@mail.utexas.edu
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Abstract

The present study investigated the effect of passivation on the kinetics of interfacial mass transport by measuring stress relaxation in electroplated Cu films with four different cap layers: SiN, SiC, SiCN, and a Co metal cap. Stress curves measured under thermal cycling showed different behaviors for the unpassivated and passivated Cu films, but were essentially indifferent for the films passivated with different cap layers. On the other hand, stress relaxation measured under an isothermal condition revealed clearly the effect of passivation, indicating that interface diffusion controls the kinetics of stress relaxation. The relaxation rates in the passivated Cu films were found to decrease in the order of SiC, SiCN, SiN, and metal caps. This correlates well with previous studies on the relationship between interfacial adhesion and electromigration. A kinetic model based on coupling of interface and grain-boundary diffusion was used to deduce the interface diffusivities and the corresponding activation energies.

Keywords

CuFilmKinetics
Type
Articles
Information
Journal of Materials Research , Volume 21 , Issue 6 , June 2006 , pp. 1512 - 1518
Copyright
Copyright © Materials Research Society 2006

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References

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