The effects of Co and Ti thin-film reactions with Si, upon the diffusion of buried Sb-doped layers, were investigated. Analysis of Sb profiles by means of secondary ion mass spectrometry showed that greatly enhanced non-uniform Sb diffusion occurred during the reaction of various thicknesses (30 to 300nm) of Co and Ti via rapid thermal annealing. A simple non-equilibrium intrinsic diffusion model was used to estimate the time-averaged excess vacancy concentrations. Concentrations which were about 107 times the equilibrium values were shown to exist during CoSi2 formation via the reaction of a 30nm Co film in Ar at 700C for 600s. Diffusion enhancement at large distances from the silicide edge was observed by using bevelling and etching techniques.

J.W.Honeycutt, G.A.Rozgonyi: Applied Physics Letters, 1991, 58[12], 1302-4