Silicidation of Co/Ti, Co/Nb, and Co/Hf Bilayers

초록

The transition temperature of CoSi to CoSi2 was found to increase with increasing the Ti interlayer thickness, which may be owing to the occupation of the terahedral sites by Ti atoms in the CoSi crystal structure as well as the blocking effect of the Ti interlayer on the diffusion of Co. Also the Co-Ti-O ternary compound formed at the metal/Si interface at the begining of silicidation . which seems to play an important role in epitaxial growth of Co silicide The final layer structures obtained after a rapid thermal annealing of the Co/Ti/(100)Si bi-layer structure turned out to be Ti oxide/Co-Ti-Si/epi-CoSi2/(100)Si. We observed that crystallographic orientations of the 500℃ formed cobalt silicide were different each other with the varying intermediate layers. Epitaxial and non-epitaxial Co-Si2 formed in Co/Nb/(100)Si. The reason why the crystallographic orientation of CoSi2 is different for those two systems seemed to be related to the formation and decomposion of stable reaction barriers at high temperture. The stable reaction barrier formed at high temperature could control the uniform diffusion of Co atoms. which enables epitaxial growth of CoSi2.