The role of Co in oxide-mediated silicidation was studied in terms of diffusion and nucleation by varying the annealing conditions, oxide thickness and implantation in Si substrates. Electroscopic imaging in transmission electron microscopy showed that SiOx acted as a 1-way diffusion barrier reducing the Co effective concentration at the cobalt silicide growth interface leading to CoSi2 as the first phase formed during silicidation. X-ray photo-electron spectroscopic analysis showed that unreacted Co coexisted with CoSi2 at the interface between the SiOx layer and Si substrate; implying that the Co diffusion rate was higher than the CoSi2 nucleation rate. An Si-implanted substrate could increase the CoSi2 nucleation rate and reduce Co accumulation.

The Study of Diffusion and Nucleation for CoSi2 Formation by Oxide-Mediated Cobalt Silicidation. J.J.Chang, C.P.Liu, T.E.Hsieh, Y.L.Wang: Surface and Coatings Technology, 2006, 200[10], 3314-8