Epitaxial Cu-Sn bulk crystals grown by electric current

C. Y. Liu, Y. J. Hu, Y. S. Liu, H. W. Tseng, T. S. Huang, C. T. Lu, Y. C. Chuang, S. L. Cheng

Research output: Contribution to journalArticlepeer-review

33 Scopus citations

Abstract

Epitaxial Cu3Sn and Cu6Sn5 grown by liquid-phase electroepitaxy (LPEE) have been demonstrated in this work. X-ray diffraction analysis reveals that LPEE-grown Cu3Sn and Cu 6Sn5 grew in particular directions (planes) with respect to the electron flow. LPEE-grown Cu3Sn grew in the 〈0 2 0〉 and 〈4 0 0〉 directions, and LPEE-grown Cu6Sn5 grew in the 〈2 0 4〉 and 〈623̄〉 directions. With the aid of a molecular simulation software tool, we conclude that the particular growth directions represent the low-resistance paths for electron flow. This means that, along those particular directions in the LPEE-grown Cu-Sn compounds, the traveling electrons would be scattered least by the lattice. Thus, as the electromigrating Cu atoms form Cu-Sn compound, the newly forming Cu-Sn unit cells would orientate themselves in those particular growth directions to facilitate electron flow. Then, the well-oriented newly formed Cu-Sn compound unit cells can incorporate the growth of the highly orientated LPEE-grown Cu-Sn compounds. In addition, the anisotropy of a number of properties of LPEE-grown Cu3Sn and Cu6Sn5, i.e. coefficient of thermal expansion, Vickers microhardness and electrical properties (resistivity, carrier mobility and carrier concentration), along the particular orientations were measured and reported.

Original languageEnglish
Pages (from-to)5713-5719
Number of pages7
JournalActa Materialia
Volume61
Issue number15
DOIs
StatePublished - Sep 2013

Keywords

  • IC packaging
  • Intermetallic compounds
  • Liquid-phase epitaxy (LPE)
  • Soldering joint

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