Semiconductor device and method for fabricating the same

1. A semiconductor device comprising:

a substrate;

a first active pattern disposed on the substrate and spaced apart from the substrate;

a gate insulating film which surrounds the first active pattern;

a first work function adjustment film which surrounds the gate insulating film and comprises carbon; and

a first barrier film which surrounds the first work function adjustment film,

wherein a carbon concentration of the first work function adjustment film increases as it goes away from the first barrier film.

2. The semiconductor device of claim 1 , wherein the carbon concentration of the first work function adjustment film decreases as it goes away from an upper surface of the substrate.

3. The semiconductor device of claim 1 , wherein the carbon concentration of the first work function adjustment film increases and then decreases, when moving from a first sidewall to a second sidewall opposite to the first sidewall of the first work function adjustment film along a plane parallel to an uppersurface of the substrate.

4. The semiconductor device of claim 1 , further comprising a second active pattern disposed on the first active pattern and spaced apart from the first active pattern.

5. The semiconductor device of claim 4 , wherein the first work function adjustment film comprises:

a first central portion which is disposed below the first active pattern and overlaps the first active pattern above;

a second central portion which is disposed between the first active pattern and the second active pattern, and overlaps the first active pattern and the second active pattern;

a third central portion which is disposed on the second active pattern, and overlaps the second active pattern; and

a side portion which extends on sidewalk of the first active pattern and sidewalls of the second active pattern to connect the first central portion, the second central portion, and the third central portion.

6. The semiconductor device of claim 1 , wherein the first work function adjustment film is an n-type work function adjustment film.

7. The semiconductor device of claim 6 , wherein the first work function adjustment film comprises at least one of Ti, Ta, W, Ru, Nb, Mo, Hf, La and any combination thereof.

8. The semiconductor device of claim 6 , further comprising:

a second work function adjustment film interposed between the gate insulating film and the first work function adjustment film,

wherein the second work function adjustment film is a p-type work function adjustment film.

9. The semiconductor device of claim 1 , wherein the first barrier film comprises TiN.

10. The semiconductor device of claim 1 , further comprising:

a second harrier film on the first barrier film,

wherein the second barrier film is in contact with the first barrier film and comprises a substance the same as that of the first barrier film.

11. The semiconductor device of claim 1 , further comprising a filling conductive film on the first barrier film.

12. The semiconductor device of claim 1 , further comprising a lower conductive film interposed between the gate insulating film and the first work function adjustment film.

13. A semiconductor device comprising:

a substrate;

a first active pattern disposed on the substrate and spaced apart from the substrate;

a gate insulating film which surrounds the first active pattern; and

a work function adjustment film which surrounds the gate insulating film and comprises carbon,

wherein the work function adjustment film comprises:

a first central portion which is disposed below the first active pattern and overlaps the first active pattern; and

a second central portion which is dispose on the first active pattern and overlaps the first active pattern,

wherein a carbon concentration of the first central portion is different from a carbon concentration of the second central portion.

14. The semiconductor device of claim 13 , wherein the carbon concentration of the second central portion is lower than the carbon concentration of the first central portion.

15. The semiconductor device of claim 13 , further comprising:

a second active pattern disposed on the first active pattern and spaced apart from the first active pattern,

wherein the work function adjustment film further comprises a third central portion which is disposed over the second active pattern and overlaps the second active pattern.

16. The semiconductor device of claim 15 , wherein a carbon concentration of the third central portion is lower than the carbon concentration of the first central portion and the carbon concentration of the second central portion.

17. The semiconductor device of claim 15 , wherein the work function adjustment film further comprises a side portion which extends on sidewalls of the first active pattern and sidewalls of the second active pattern to connect the first central portion, the second central portion, and the third central portion.

18. The semiconductor device of claim 17 , wherein a carbon concentration of the side portion of the work function adjustment film gradually decreases as it goes away from an upper surface of the substrate.

19. A semiconductor device comprising:

a gate insulating film on a substrate;

an n-type work function adjustment film comprising carbon on the gate insulating film; and

a first barrier film comprising on the n-type work function adjustment film,

wherein a carbon concentration of the n-type work function adjustment film increases as it goes away from the first barrier film.

20. The semiconductor device of claim 19 , wherein the n-type work function adjustment film comprises TiAlC.