The properties of phosphorus‐doped molybdenum silicide as a gate electrode, interconnecting material, and impurity diffusion source for LSI's have been studied. The phosphorus‐doped molybdenum silicide films were deposited by co‐sputtering using specially designed Mo and Si targets in a atmosphere. decomposed to P and during sputtering and the phosphorus combined with Mo and Si. Typically, a phosphorus concentration of in the films was used. As‐deposited films had amorphous structure and high resistivity. After the films were annealed at temperatures above 800°C, they became polycrystalline and resistivity was decreased. The resistivity of the film with a Mo/Si ratio of 2 to 1 was with annealing at 1000°C in . Phosphorus was able to diffuse from the doped molybdenum silicide films to the Si substrate during annealing in . After high temperature annealing up to 1100°C, the contact resistance between the molybdenum silicide and the silicon substrate was below . The reliability of doped molybdenum silicide gate MOSFET's is as good as polysilicon gates and the threshold voltage shift is within ±20 mV under stress conditions of 2.5 MV/cm for 1000 hr at 150°C.