Patent ID: 8288221

Claim:
A method of manufacturing a semiconductor device comprising a MIS transistor, the method comprising the steps of: (a) forming a silicon oxide film on a main surface of a semiconductor substrate; (b) forming a membranous base material containing hafnium and oxygen on the silicon oxide film; (c) forming a membranous admixture thinner than the base material and made of only a metal element on the base material; (d) forming a protective film on the admixture; (e) diffusing the admixture into the base material in a state of having the protective film, thereby forming a mixed film having a higher dielectric constant than silicon oxide and containing hafnium and oxygen of the base material and the metal element of the admixture on the silicon oxide film; (f) removing the protective film after the step (e); (g) forming a conductive film on the mixed film; and (h) forming a gate electrode made of the conductive film, and a gate insulating film formed of the mixed film and the silicon oxide film.