Method of manufacturing semiconductor device and semiconductor device
A base insulating film containing hafnium and oxygen is formed on a silicon oxide (SiO 2 ) film formed on a main surface of a substrate. Subsequently, a metal thin film thinner than the base insulating film and made of only a metal element is formed on the base insulating film, and a protective film having humidity resistance and oxidation resistance is formed on the metal thin film. Then, by diffusing the entire metal element of the metal thin film into the base insulating film in a state of having the protective film, a mixed film (high dielectric constant film) thicker than the silicon oxide film and having a higher dielectric constant than silicon oxide and containing hafnium and oxygen of the base insulating film and the metal element of the metal thin film is formed on the silicon oxide film.
1. 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.
2. The method of manufacturing a semiconductor device according to claim 1 , wherein
the MIS transistor is n-channel type, and,
in the step (c), the admixture made of a metal element constituting a metal oxide having a smaller electronegativity than hafnium oxide is formed.
3. The method of manufacturing a semiconductor device according to claim 1 , wherein
the MIS transistor is p-channel type, and,
in the step (c), the admixture made of a metal element constituting a metal oxide having a larger electronegativity than hafnium oxide is formed.
4. The method of manufacturing a semiconductor device according to claim 1 , wherein the admixture is diffused into the base material by an annealing treatment in the step (e).
5. The method of manufacturing a semiconductor device according to claim 1 , wherein
the admixture is formed in a vacuum state in the step (c), and
the protective film is formed in the step (d) while keeping the vacuum state.
6. The method of manufacturing a semiconductor device according to claim 1 , wherein a titanium nitride film is formed as the protective film in the step (d).