XRD and ToF-SIMS study of intermetallic void formation in Cu-Sn micro-connects

G. Ross*, V. Vuorinen, M. Krause, S. Reissaus, M. Petzold, M. Paulasto-Kröckel

*Corresponding author for this work

Research output: Contribution to journalArticleScientificpeer-review

2 Citations (Scopus)


An identified reliability challenge of significant importance to Cu-Sn bonding for 3D integration is Cu-Sn intermetallic void formation. Voids, often referred to as Kirkendall voids, form within the inter-diffusional zone between Cu and Sn, more specifically within the intermetallic compound Cu3Sn. The root-cause(s) of void formation is not well understood, therefore this study is designed to understand under what conditions voids form. The two main hypotheses for the root-causes of void formation are (i) the imbalance of diffusion rates between Cu and Sn during the formation of Cu-Sn intermetallic compounds and the resulting residual stresses and (ii) the co-deposition of impurities during Cu electroplating to void formation. Therefore, an ex- and in-situ x-ray diffraction (XRD) study is used to probe the material state as a function of thermal annealing, and a time-of-flight mass spectroscopy (ToF-SIMS) study is used to detect impurities co-deposited during Cu electroplating and to understand the effects of thermal annealing on the impurities' kinetic behaviour.

Original languageEnglish
Pages (from-to)390-394
JournalMicroelectronics Reliability
Publication statusPublished - 2017
MoE publication typeA1 Journal article-refereed


  • 3D integration
  • Intermetallic voids
  • Kirkendall voids
  • Reliability
  • Time-of-flight mass spectroscopy
  • X-ray diffraction


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