Geometry-dependent phase, stress state and electrical properties in nickel-silicide nanowires

C. C. Wang, W. T. Lai, Y. Y. Hsiao, I. H. Chen, T. George, Pei-Wen Li

Research output: Contribution to journalArticle

Abstract

We report that the geometry of single-crystalline Si nanowires (NWs) prior to salicidation at 500 °C is the key factor controlling the phase, stress state, and electrical resistivity of the resulting NixSiy NWs of width less than 100 nm. This is a radical departure from previous observations of a single phase formation for nickel silicides generated from the silicidation of bulk Si substrates. The phase transition from NiSi for large NWs ( W Si NW = 250-450 nm) to Ni2Si for small NWs ( W Si NW = 70-100 nm) is well correlated with the observed volumetric expansion and electrical resistivity variation with the NW width. For the extremely small dimensions of NixSiy NWs, we propose that the preeminent, kinetics-based Zhang and d'Heurle model for salicidation be modified to a more thermodynamically-governed, volume-expansion dependent NixSiy phase formation. A novel, plastic deformation mechanism is proposed to explain the observed, geometry-dependent NixSiy NW phase formation that also strongly influences the electrical performance of the NWs.

Original languageEnglish
Article number205102
JournalJournal of Physics D: Applied Physics
Volume49
Issue number20
DOIs
StatePublished - 15 Apr 2016

Keywords

  • nanowire
  • nickel silicide
  • plastic deformation
  • resistivity
  • stress

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