Structural relationship of polycrystalline cobalt silicide lines to (001) silicon substrate and their thermal stability

We have investigated the crystalline quality of 0.6-1.2 mum poly-CoSi2, lines, formed on (001) silicon by a standard salicide process. The microstructure of silicide grains has been investigated by TEM and HRTEM techniques and related to their location inside the strip. The grains at the centre of the line were randomly oriented with respect to the substrate unlike at the edges, where some interesting epitaxial relationships were detected. Selected area diffraction (SAD) analyses on the line section indicated the presence of both A- and B-type epitaxial regions even inside the same grain, whose interface to silicon lies along the (1,1,1) planes. In these regions, high-resolution transmission electron microscopy (HRTEM) analyses have shown misfit dislocations inserted along the (111)planes to compensate the lattice mismatch. High temperature anneals mainly deteriorate the line edges with serious damage to their electrical performance.