Published online by Cambridge University Press: 26 February 2011
Thin-film Ni-Si lateral-diffusion couples were annealed at 450°C for 12 hours to cause formation of the suicide phases: Ni3Si, Ni5-Si2, Ni2Si, and NiSi. Scanning transmission electron microscopy (STEM) was used to investigate the suicide growth. The mechanism of Ni transport to the growth front was shown to be bulk phase diffusion, as evidenced by a bulk phase concentration gradient of 0.03 atomica Ni/nm in the NiSi phase. The transition from thin film kinetic behavior to bulk couple kinetic behavior was found to be greater than 200 nm. The absence of the Ni3Si2 phase in the lateral-diffusion couple was attributed to a nucleation barrier. An excess amount of Ni in the Ni2Si phase at the Ni2Si-NiSi interface indicates the interdiffusivity is lower in NiSi than in Ni2Si, thereby limiting Ni diffusion out of the Ni2Si phase.