Formation and properties of ternary silicide (CoxNi1-x)Si2 thin films

A ternary silicide (Co_xNi_1-x)Si₂ formed by Ni and Co thin films or Ni, Co and Ti thin films deposited on a Si(100) substrate is studied. The results show that a highly conductive silicide (Co_xNi_1-x)Si₂ can be formed by solid phase reaction of either Ni/Co/Si or Co/Ni/Si structures. The resistivity of the silicide films is in the range of (15-20) μΩ.cm. The formation temperature of (Co_xNi _1-x)Si₂ is rather low compared with the disilicides of Co and Ni. XRD data show that (Co_xNi_1-x )Si₂ has a CaF₂ structure and its lattice constant is between that of CoSi₂ and NiSi₂. (Co _xNi_1-x)Si₂ can also be formed by rapid thermal annealing of a Co/Ni/Ti/Si multilayer structure. A quite low χ_min value is shown by RBS/channeling investigation. The joint has a better epitaxy quality as compared with that without a Ti interlayer. It is more uniform and has a good thermal stability and low resistivity. Experiments with two step annealing and chemical selective etching demonstrate that a self-aligned silicided contact and a gate-level interconnection structure can be formed on Si wafers