Dopant diffusion in tungsten silicide

The dopant (B, P, and As) redistribution in a silicide on polycrystalline silicon structure after annealing at 800 and 1000 0C was studied. The distribution of boron was found to be quite different from these of phosphorus and arsenic. At 1000 0C, the distribution coefficient for boron at the WSi2/polycrystalline silicon interface was found to be 2.7. The solubilities of phosphorus and arsenic in WSi2 at 1000 0C were estimated to be 6 x 1019 and 1.6 x 1019 atoms/cm3, respectively. At 800 0C, the diffusion coefficient for the dopants was found to be equal to, or greater than 3.3 x 10-12 cm2/s, which is at least three orders of magnitude larger than in silicon