A thin Ti-siuicide film is widely used today as the low resistance shunt in a semiconductor chip. As the feature size in the chip shrinks to sub-quarter micron, the thin Ti-silicide film formed on such narrow lines transforms from C49 to C54 at increasing temperatures and agglomerates at decreasing temperatures, closing the process window for Ti-salicide process. In contrast, low resistivity Co-silicide thin films can be formed on narrow lines below the agglomeration temperature. In addition, an epitaxial CoSi2 with a flat interface can be formed in source/drain areas, enabling the formation of very shallow junctions with low leakage current. Experimental results on formation of silicides from Co/Ti bilayers and thermal stability of the CoSi2 films will be presented, with special emphasis on the sheet resistance of the silicide film versus poly-line width down to 0.15 umn. Interaction between dopants and silicide films will also be discussed.