Effect of excess silicon on behavior of LPCVD WSi_x films on silicon

Abstract

This paper addresses the important effects of excess silicon in low pressure chemical vapor deposition tungsten silicide films on resistivity, adhesion, and stress as a function of annealing temperature with physical interpretation. Excess silicon can be incorporated in the films to lower stress, but a consequence of this is that the resistivity is increased. On annealing such fimls, excess silicon tends to diffuse out of the silicide increasing stress and lowering resistivity. Results are presented of both the stress in the films and their resistivity as a function of annealing conditions. The annealing ambient also plays a strong role in the rate at which excess silicon migrates to the surface. Oxygen greatly enhances the rate compared with argon or nitrogen. © 1988.