Geometry-dependent phase, stress state and electrical properties in nickel-silicide nanowires. (15th April 2016)

• Record Type: Journal Article
• Authors: Wang, C C; Lai, W T; Hsiao, Y Y; Chen, I H; George, T; Li, P W
• Is Part Of: Journal of physics. Volume 49:Number 20(2016)
• Publication Date: 2016-04-15
• Subjects: nickel silicide -- nanowire -- stress -- plastic deformation -- resistivity; Physics -- Periodicals; 530
• DOI: 10.1088/0022-3727/49/20/205102
• Languages: English
• ISSNs: 0022-3727

Abstract

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 Ni x Si y 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 Ni2 Si 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 Ni x Si y 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 Ni x Si y phase formation. A novel, plastic deformation mechanism is proposed to explain the observed, geometry-dependent Ni x Si y NW phase formation that also strongly influences the electrical performance of the NWs.