STM OBSERVATION OF NICKEL SILICIDES ON SI(001)

The formation of NiSi2 on the clean 2 x 1 and the hydrogen-terminated Si(001) substrates has been examined and compared by using scanning tu nneling microscopy. The deposited Ni atoms form clusters on both subst rates at room temperature. After annealing at elevated temperatures, t he clusters coalesce and inhomogeneous surface morphology of the NiSi2 is obtained in the case of the deposition onto the clean surface, due to immediate Ni diffusion into the bulk Si. In contrast, the NiSi2 fi lms formed by using the hydrogen-terminated surface have a large flat morphology. This is explained as being the result of the enhanced ''in -plane'' nickel diffusion and the blocking of inter-diffusion by the e xistence of stable Si-H bonds formed on the surface.