An extremely reliable TiSix/TiNx diffusion barrier was formed by the rapid thermal annealing of a thin Ti layer which was sputtered into the contacts before Al metallization. The effects of this barrier metal process on the material properties of heavily implanted n+ and p+ regions were studied. The TiNx-to-TiSix thickness ratio is determined by the dominant reaction at the sintering temperature. Arsenic implanted in the substrate tends to substantially retard the silicidation of Ti. Substantial redistribution of both B and As across the silicide layer was observed during rapid thermal annealing. Film stress was found to be greatly affected by the annealing temperature. Contact resistance, contact electromigration and thermal stability of the structure were also investigated.