Semiconductor device and method for fabricating semiconductor device

1. A semiconductor device, comprising:

a contact plug electrically connected to a semiconductor substrate;

a first barrier metal film with a columnar crystal structure arranged in contact with the semiconductor substrate at least on a bottom surface side of the contact plug;

an amorphous film made of a material of the first barrier metal film arranged in contact with the first barrier metal film at least on the bottom surface side of the contact plug;

a second barrier metal film made of a material identical to that of the first barrier metal film and having a columnar crystal structure, at least a portion of which is arranged in contact with the amorphous film on the bottom surface side and a side surface side of the contact plug; and

a dielectric film arranged on the side surface side of the contact plug.

2. The semiconductor device according to claim 1 , further comprising a metal containing film arranged in contact with the second barrier metal film and the contact plug on the bottom surface side and the side surface side of the contact plug.

3. The semiconductor device according to claim 2 , wherein ruthenium (Ru) is used as a material of the metal containing film.

4. The semiconductor device according to claim 1 , wherein copper (Cu) is used as a material of the contact plug and

titanium nitride (TiN) is used as a material of the first and second barrier metal films.

5. A semiconductor device, comprising:

a contact plug electrically connected to a semiconductor substrate;

a first barrier metal film with a columnar crystal structure arranged in contact with the semiconductor substrate at least on a bottom surface side of the contact plug;

a second barrier metal film made of a material identical to that of the first barrier metal film and with a columnar crystal structure that is arranged on the bottom surface side and a side surface side of the contact plug and whose crystalline interface is shifted from that of the first barrier metal film;

a metal containing film arranged in contact with the second barrier metal film and the contact plug on the bottom surface side and the side surface side of the contact plug; and

a dielectric film arranged on the side surface side of the contact plug.

6. The semiconductor device according to claim 5 , wherein ruthenium (Ru) is used as a material of the metal containing film.

7. The semiconductor device according to claim 5 , wherein copper (Cu) is used as a material of the contact plug and

titanium nitride (TiN) is used as a material of the first and second barrier metal films.

8. The semiconductor device according to claim 5 , further comprising an amorphous film made of a material of the first barrier metal film between the first and second barrier metal films.

9. A method for fabricating a semiconductor device, comprising:

forming a dielectric film above a semiconductor substrate;

forming an opening cutting through to the semiconductor substrate in the dielectric film;

forming a first barrier metal film with a columnar crystal structure in the opening;

forming an amorphous film made of a material of the first barrier metal film by reforming a surface of the first barrier metal film;

forming a second barrier metal film made of a material identical to that of the first barrier metal film and with a columnar crystal structure above the amorphous film in the opening; and

depositing a contact plug material inside the opening after the second barrier metal film being formed.

10. The method according to claim 9 , further comprising: forming a metal containing film above the second barrier metal film in the opening after the second barrier metal film has been formed and before the contact plug material has been deposited.

11. The method according to claim 10 , wherein ruthenium (Ru) is used as a material of the metal containing film.

12. The method according to claim 11 , further comprising: performing heat treatment after the metal containing film has been formed and before the contact plug material has been deposited.

13. The method according to claim 12 , wherein a temperature of the heat treatment is 200° C. or below.

14. The method according to claim 13 , wherein the second barrier metal film is formed by a chemical vapor deposition (CVD) method.

15. The method according to claim 12 , further comprising: performing plasma treatment of the second barrier metal film after the second barrier metal film has been formed and before the metal containing film has been formed.

16. The method according to claim 9 , further comprising: performing plasma treatment of the second barrier metal film after the second barrier metal film has been formed and before the contact plug material has been deposited.

17. The method according to claim 16 , wherein the second barrier metal film is exposed to a plasma atmosphere using either ammonia (NH 3 ) or hydrogen (H 2 ) when performing the plasma treatment.

18. The method according to claim 17 , wherein the second barrier metal film is formed by a chemical vapor deposition (CVD) method.

19. The method according to claim 9 , wherein the surface of the first barrier metal film is reformed by the first barrier metal film being exposed to a plasma atmosphere.

20. The method according to claim 9 , wherein the first barrier metal film is a titanium nitride (TiN) film obtained by nitriding titanium (Ti) formed by a plasma CVD method and

the second barrier metal film is a titanium nitride (TiN) film formed by a thermal CVD method.