Interconnection structure, fabricating method thereof, and semiconductor device using the same

1. A semiconductor device comprising:

a semiconductor substrate comprising a contact region;

a silicide present on the contact region;

a dielectric layer present on the semiconductor substrate, the dielectric layer comprising an opening to expose a portion of the contact region;

a conductor present in the opening;

a barrier layer present between the conductor and the dielectric layer; and

a metal layer present between the barrier layer and the dielectric layer, wherein a Si concentration of the silicide is varied along a height of the silicide.

2. The semiconductor device of claim 1 , wherein the metal layer is present between the barrier and the dielectric layer and is not present between the barrier layer and the silicide.

3. The semiconductor device of claim 1 , wherein the Si concentration is decreased along the height of the silicide.

4. The semiconductor device of claim 1 , wherein the Si concentration at an interface between the silicide and the barrier layer is less than that at an interface between the silicide and the contact region.

5. The semiconductor device of claim 1 , wherein a material of the silicide comprises TiSi.

6. The semiconductor device of claim 1 , wherein a material of the silicide comprises TiSiGe, and a Ge concentration is varied along the height of the silicide as the Si concentration.

7. The semiconductor device of claim 1 , wherein the contact region is an epitaxy structure.

8. The semiconductor device of claim 1 , wherein the contact region is a semiconductor pad.

9. An interconnection structure comprising:

a silicide;

a conductor;

a barrier layer present on a sidewall of the conductor and present between the silicide and the conductor; and

a metal layer present at sidewalls of the barrier layer, wherein a Si concentration of the silicide is decreased along a height of the silicide.

10. The interconnection structure of claim 9 , wherein the metal layer is not present between the barrier layer and the silicide.

11. The interconnection structure of claim 9 , wherein the metal layer comprises Ti, Co, Ni, Pt, or W.

12. The interconnection structure of claim 9 , wherein the barrier layer comprises Ta or Ti.

13. The interconnection structure of claim 9 , wherein the Si concentration at a bottom of the silicide is less than that at a top of the silicide.

14. The interconnection structure of claim 9 , wherein the barrier layer is directly in contact with the silicide.

15. The interconnection structure of claim 9 , wherein the conductor comprises W or Cu.

16. A method of fabricating an interconnection structure, the method comprising:

forming an opening in a dielectric layer to expose a portion of a contact region;

forming a metal layer on a sidewall of the opening and on the contact region;

forming a barrier layer on the metal layer; and

performing an annealing process after the barrier layer is formed on the metal layer to form a silicide between the barrier layer and the contact region, wherein a Si concentration of the silicide is decreased along a height of the silicide.

17. The method of claim 16 , wherein a portion of the metal layer between the barrier layer and the contact region is reacted with the contact region, so that the metal layer is not present between the barrier layer and the silicide.

18. The method of claim 16 , further comprising forming a conductor filling the opening, wherein the conductor is an interconnect structure in the dielectric layer.

19. The method of claim 16 , wherein the annealing process comprises an annealing temperature and an annealing duration, wherein the annealing temperature is less than 700 degrees Celsius, and wherein the annealing duration is less than 120 seconds.

20. The method of claim 16 , wherein the silicide is a titanium silicide, and wherein the annealing process comprises a transfer from a high-resistivity phase of the titanium silicide to a low-resistivity phase of the titanium silicide.