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 °C was studied. The distribution of boron was found to be quite different from these of phosphorus and arsenic. At 1000 °C, 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 °C were estimated to be 6×1019 and 1.6×1019 atoms/cm3, respectively. At 800 °C, the diffusion coefficient for the dopants was found to be equal to, or greater than 3.3×10−12 cm2/s, which is at least three orders of magnitude larger than in silicon.