TI CO BILAYERS IN SALICIDE TECHNOLOGY - ELECTRICAL EVALUATION/

A detailed investigation of the applicability of Ti/Co bilayers for th e salicide technology is presented. In the first place the silicide fo rmation on poly-Si gale lines using Ti/Co bilayers has been studied. I t is demonstrated that lateral silicide growth over the spacers can be avoided by making use of a two-step silicidation. In addition, the th ermal stability of CoSi2 obtained on small poly-Si lines by two-step s ilicidation of a Ti/Co bilayer has been investigated and compared to t he thermal stability of CoSi, obtained by standard silicidation of a 2 0 nm Co film. The performance of Ti/Co silicidation with respect to br idging has been studied making use of a special yield monitor chip wit h dedicated bridging cells. Similar as for standard Co silicidation, c lose to 100% yield numbers are obtained for two-step Ti/Co silicidatio n. Finally, the contact resistance between the silicide and the p(+) a nd n(+) diffusion areas has been evaluated making use of four terminal cross-bridge Kelvin resistor structures. Contact resistivity values w ere calculated to be in the range of 5-6 X 10(-7) Omega . cm(2) for Co Si2/p(+) contacts and in the range of 1-2 x 10(-7) Omega . cm(2) for C oSi2/n(+) contacts.