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Effect of passivation on stress relaxation in electroplated copper films

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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.

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Authors and Affiliations

  1. Laboratory for Interconnect and Packaging, University of Texas, Austin, Texas, 78712, USA

    Dongwen Gan & Paul S. Ho

  2. Department of Aerospace Engineering and Engineering Mechanics, University of Texas, Austin, Texas, 78712, USA

    Yaoyu Pang & Rui Huang

  3. Intel Corporation, Hillsboro, Oregon, 97214, USA

    Jihperng Leu, Jose Maiz & Tracey Scherban

Authors
  1. Dongwen Gan
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  2. Paul S. Ho
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  3. Yaoyu Pang
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  4. Rui Huang
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  5. Jihperng Leu
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  6. Jose Maiz
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  7. Tracey Scherban
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Correspondence to Rui Huang.

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Gan, D., Ho, P.S., Pang, Y. et al. Effect of passivation on stress relaxation in electroplated copper films. Journal of Materials Research 21, 1512–1518 (2006). https://doi.org/10.1557/jmr.2006.0196

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  • DOI: https://doi.org/10.1557/jmr.2006.0196

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