Semiconductor device and method of manufacturing the same

1. A semiconductor device comprising:

a semiconductor substrate;

a capacitor provided above the semiconductor substrate;

an insulation region which covers the capacitor and has a first hole and a second hole, the first hole being provided apart from the capacitor and extending in a vertical direction with respect to a main surface of the semiconductor substrate, the second hole reaching an electrode of the capacitor, extending in the vertical direction with respect to the main surface of the semiconductor substrate and being shallower than the first hole;

a tungsten plug provided in the first hole;

a first oxygen barrier film provided between the tungsten plug and a side wall of the first hole; and

a conductive plug provided in the second hole and connected to the electrode of the capacitor.

2. The semiconductor device according to claim 1 , further comprising a second oxygen barrier film provided on the insulation region.

3. The semiconductor device according to claim 1 , further comprising a transistor provided on the semiconductor substrate, wherein the tungsten plug is electrically connected to the transistor.

4. The semiconductor device according to claim 1 , further comprising a wire provided on the insulation region and connected to the tungsten plug.

5. The semiconductor device according to claim 1 , wherein the first oxygen barrier film includes at least one of a silicon nitride film, an alumina film and a titanium oxide film.

6. The semiconductor device according to claim 1 , wherein a dielectric film of the capacitor includes a ferroelectric film.

7. The semiconductor device according to claim 6 , wherein the ferroelectric film is formed of a metal oxide.

8. A method of manufacturing a semiconductor device, comprising:

forming a capacitor above a semiconductor substrate, the capacitor being covered with an insulation region;

forming a first hole in the insulation region, the first hole being provided apart from the capacitor and extending in a vertical direction with respect to a main surface of the semiconductor substrate;

forming a first oxygen barrier film on a side wall of the first hole;

forming a tungsten plug in the first hole being provided with the first oxygen barrier film;

forming a second hole in the insulation region, the second hole reaching an electrode of the capacitor, extending in the vertical direction with respect to the main surface of the semiconductor substrate and being shallower than the first hole; and

forming a conductive plug in the second hole.

9. The method according to claim 8 , further comprising: forming a second oxygen barrier film on the insulation region and the tungsten plug, before forming the second hole.

10. The method according to claim 8 , further comprising: annealing the capacitor in an atmosphere containing oxygen, after forming the second hole.

11. The method according to claim 8 , further comprising: forming a transistor on the semiconductor substrate, before forming the capacitor, wherein the tungsten plug is electrically connected to the transistor.

12. The method according to claim 8 , further comprising: forming a wire on the insulation region, the wire being connected to the tungsten plug.

13. The method according to claim 8 , wherein the first oxygen barrier film includes at least one of a silicon nitride film, an alumina film and a titanium oxide film.

14. The method according to claim 8 , wherein a dielectric film of the capacitor includes a ferroelectric film.

15. The method according to claim 8 , wherein the ferroelectric film is formed of a metal oxide.