Formation and properties of ternary silicide (Co/sub x/Ni/sub 1-x/)Si/sub 2/ thin films

A ternary silicide (Co/sub x/Ni/sub 1-x/)Si/sub 2/ 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/sub x/Ni/sub 1-x/)Si/sub 2/ 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) /spl mu//spl Omega/.cm. The formation temperature of (Co/sub x/Ni/sub 1-x/)Si/sub 2/ is rather low compared with the disilicides of Co and Ni. XRD data show that (Co/sub x/Ni/sub 1-x/)Si/sub 2/ has a CaF/sub 2/ structure and its lattice constant is between that of CoSi/sub 2/ and NiSi/sub 2/. (Co/sub x/Ni/sub 1-x/)Si/sub 2/ can also be formed by rapid thermal annealing of a Co/Ni/Ti/Si multilayer structure. A quite low /spl chi//sub 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.