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Grain structure effect on electromigration reliability of Cu interconnects with CoWP capping

Published online by Cambridge University Press:  11 October 2011

Lijuan Zhang ,
Paul S. Ho ,
Oliver Aubel ,
Christian Hennesthal  and
Ehrenfried Zschech
Lijuan Zhang*
Affiliation:
Laboratory for Interconnect and Packaging, Microelectronics Research Center PRC/MER, The University of Texas at Austin, Austin, Texas 78712
Paul S. Ho
Affiliation:
Laboratory for Interconnect and Packaging, Microelectronics Research Center PRC/MER, The University of Texas at Austin, Austin, Texas 78712
Oliver Aubel
Affiliation:
GLOBALFOUNDRIES Dresden Module One LLC & Co. KG, 01109 Dresden, Germany
Christian Hennesthal
Affiliation:
GLOBALFOUNDRIES Dresden Module One LLC & Co. KG, 01109 Dresden, Germany
Ehrenfried Zschech
Affiliation:
Fraunhofer Institute for Non-Destructive Testing IZFP, Dresden, Germany
*
a)Address all correspondence to this author. e-mail: [email protected]
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Abstract

This article investigates the effect of grain structure on electromigration (EM) reliability of dual-damascene Cu interconnects with a CoWP capping layer, including the lifetime and statistics. Downstream EM tests were performed on two sets of CoWP-capped Cu interconnects with different grain sizes. Compared to Cu interconnects with the standard SiCN cap layer, the CoWP capping clearly improved the EM lifetime by ∼24× for the small grain structure and by another ∼14× for the large grain structure. Here, the effect of grain structure on EM lifetime was attributed to the grain boundary contribution to mass transport. The lifetime improvement, however, was accompanied with an increase in the statistical deviation, increasing from 0.27 for the SiCN cap to 0.53 for the small grain structure and to 0.88 for the large grain structure with the CoWP cap. This was attributed to the effect of grain structure in changing the statistical distribution of flux divergence sites and thus the failure statistics.

Keywords

ElectromigrationGrain size
Type
Articles
Information
Journal of Materials Research , Volume 26 , Issue 21 , 14 November 2011 , pp. 2757 - 2760
Copyright
Copyright © Materials Research Society 2011

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References

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