Formation process and microstructural evolution of Ni-silicide layers grown by chemical vapor deposition of Si on Ni substrates

The formation process and microstructural evolution of Ni-silicide layers formed by chemical vapour deposition (CVD) of Si on Ni substrate at deposition temperatures between 900 and 1050 °C using horizontal hot-wall reactor and SiCl4–H2 gas mixtures was investigated. The Ni-silicide layers grew sequentially in a series of γ-Ni5Si2, δ-Ni2Si and θ-Ni2Si layers with increasing deposition time. After an incubation time necessary for nucleation of each Ni-silicide phase, the growth kinetics of each layer obeyed a parabolic rate law and was controlled by solid-state diffusion of Ni leading to void formation at the interface of the Ni-silicide layers and the Ni substrate. The growth rates of γ-Ni5Si2 and δ-Ni2Si layers were faster at the early deposition stage than those at the later deposition stage. The formation process and microstructures of each Ni-silicide layer was influenced by the effect of deposition parameters especially on the difference between the Si flux supplied by CVD process and the Ni flux diffusing through each Ni-silicide layer.