Method for manufacturing semiconductor device

1. A semiconductor device comprising a capacitor, the capacitor comprising:

a lower electrode comprising titanium nitride connected to a semiconductor substrate,

a dielectric film comprising a layer of zirconium oxide as a primary constituent, the dielectric film being formed on said lower electrode,

an upper electrode comprising a titanium nitride film, the upper electrode being formed on said dielectric film, and

a protective film comprising titanium oxide as a primary constituent and being inserted in at least one of the interface between said upper electrode and said dielectric film and the interface between said lower electrode and said dielectric film.

2. The semiconductor device according to claim 1 ,

wherein said protective film is inserted in either of the interface between said upper electrode and said dielectric film and the interface between said lower electrode and said dielectric film.

3. The semiconductor device according to claim 1 ,

wherein said protective film is inserted in both of the interface between said upper electrode and said dielectric film and the interface between said lower electrode and said dielectric film.

4. The semiconductor device according to claim 1 ,

wherein said protective film being inserted in the interface between said upper electrode and said dielectric film is a titanium oxide film with a film thickness of 0.4 to 5 nm.

5. The semiconductor device according to claim 4 ,

wherein said protective film being inserted in the interface between said upper electrode and said dielectric film is a polycrystalline titanium oxide film with a film thickness of 1 to 5 nm and has conductivity.

6. The semiconductor device according to claim 1 ,

wherein said protective film being inserted in the interface between said lower electrode and said dielectric film has a film thickness of not less than 0.4 nm and not more than 2 nm.

7. The semiconductor device according to claim 1 ,

wherein said dielectric film has a portion of the dielectric film containing aluminum oxide.

8. The semiconductor device according to claim 7 ,

wherein said dielectric film comprising zirconium oxide as a primary constituent has a composite ratio of 0.8 or more, the composite ratio being indicated Z/(Z+M) where Z is the number of zirconium atoms and M is the number of aluminum atoms.

9. The semiconductor device according to claim 1 ,

wherein said dielectric film comprising zirconium oxide as a primary constituent has a film thickness of 5 to 8 nm.

10. The semiconductor device according to claim 1 ,

wherein said dielectric film has a stacked structure of a first dielectric film made of a polycrystalline zirconium oxide film, a second dielectric film made of an amorphous aluminum oxide film on said first dielectric film, and a third dielectric film made of a polycrystalline zirconium oxide film on said second dielectric film, and

wherein said protective film comprising titanium oxide is formed on said third dielectric film.

11. The semiconductor device according to claim 8 ,

wherein the film thickness of said first and third dielectric films in total falls within the range from 5 nm to 7 nm.

12. The semiconductor device according to claim 1 ,

wherein SiO 2 equivalent oxide thickness (EOT) of said dielectric film is 1.2 nm or less.

13. The semiconductor device according to claim 1 ,

wherein said lower electrode has a three-dimensional structure.

14. The semiconductor device according to claim 13 , further comprising a second upper electrode made of a silicon germanium film containing boron on said titanium nitride film for the upper electrode.

15. The semiconductor device according to claim 1 ,

wherein said capacitor has the leakage current characteristic of a current density of 1E-7(A/cm 2 ) or less when a voltage within the range of ±2 V is applied, after being annealed at 400° C. to 450° C. under reducing atmosphere containing hydrogen gas after the formation of the capacitor.