Reaction of Co and capping layers and its effect on CoSi₂ formation in Si/SiO_x/Co system

The role of the reaction between the capping layer and Co on the crystalline nature of CoSi₂ films in refractory metal-capped Si/SiO_x/Co system has been investigated. The epitaxial CoSi₂ film was obtained in the capping layers (Ti, Zr) with high tendency of mixing between Co and the capping layer. Amorphous Ti–Co layer was produced at 450 °C, and its thickness was increased at 550 °C. The formation of amorphous Ti–Co layer during low-temperature annealing may be responsible for the formation of epitaxial CoSi₂. Meanwhile, the polycrystalline CoSi₂ was formed in the capping layer (Cr, Mo) with low tendency of mixing. These results can be explained by the fact that the mixing layer formed from the reaction between Co and refractory metal control the Co diffusion to the Si substrate as well as the thin SiO_x between Co and Si. © 2000 American Institute of Physics.