Capacitor and method for fabricating the same

1. A method for fabricating a capacitor, comprising:

forming a lower electrode;

forming a first dielectric layer over the lower electrode;

forming a second dielectric layer of an amorphous high-k dielectric material over the first dielectric layer;

forming a third dielectric layer over the second dielectric layer, wherein the third dielectric layer is thicker than the first dielectric layer; and

forming an upper electrode over the third dielectric layer.

2. The method in claim 1 , wherein the second dielectric layer comprises a tantalum oxide layer.

3. The method in claim 1 , wherein each of the first dielectric layer and the third dielectric layer comprises a zirconium oxide layer.

4. The method in claim 1 , wherein the second dielectric layer comprises a tantalum oxide layer, and each of the first dielectric layer and the third dielectric layer comprises a zirconium oxide layer.

5. The method in claim 3 , wherein the forming of the first dielectric layer and the forming of the third dielectric layer are performed by using an atomic layer deposition (ALD) process at a temperature less than approximately 350° C.

6. The method in claim 5 , wherein each of the forming of the first dielectric layer and the forming of the third dielectric layer is performed at a pressure ranging from approximately 0.1 Torr to approximately 10 Torr and a temperature ranging from approximately 250° C. to approximately 350° C.

7. The method in claim 6 , wherein each of the forming of the first dielectric layer and the forming of the third dielectric layer comprises:

adsorbing a zirconium source;

performing a first purge process to remove unreacted zirconium source;

supplying a reaction gas; and

performing a second purge process to remove unreacted gas and reaction by-products, wherein the zirconium source adsorbing process, the first purge process, the reaction source supplying process, and the second purge process are repeated.

8. The method in claim 7 , wherein, during adsorbing the zirconium source, a gas selected from the group consisting of Zr[NC 2 H 5 CH 3 ] 4 , Zr[N(CH 3 ) 2 ] 4 , Zr[OC(CH 3 ) 2 CH 2 OCH 3 ] 4 , Zr[OC(CH 3 ) 3 ] 4 , ZrCl 4 , and ZrI a , and a combination thereof is used as a precursor gas, and the precursor gas including Ar gas flows at a flow rate of approximately 100 sccm to approximately 2,000 sccm for approximately 2 seconds to approximately 10 seconds.

9. The method in claim 7 , wherein, during performing the first purge process or the second purge process, N 2 gas or Ar gas flows at a flow rate of approximately 100 sccm to approximately 3,000 sccm for approximately 2 seconds to approximately 10 seconds.

10. The method in claim 7 , wherein, during supplying the reaction gas, a gas selected from the group consisting of O 3 gas, H 2 O gas and O 2 gas, and a combination thereof flows at a flow rate of approximately 100 sccm to approximately 3,000 sccm for approximately 5 seconds to approximately 10 seconds.

11. The method in claim 2 , wherein the forming of the second dielectric layer is performed by using an ALD process at a temperature higher than that in forming the first dielectric layer and lower than approximately 400° C.

12. The method in claim 11 , wherein the forming of the second dielectric layer is performed at a pressure ranging from approximately 0.1 Torr to approximately 10 Torr and a temperature ranging from approximately 100° C. to approximately 400° C.

13. The method in claim 12 , wherein each of the forming of the second dielectric layer comprises:

adsorbing a tantalum source;

performing a first purge process to remove unreacted tantalum source;

supplying a reaction gas; and

performing a second purge process to remove unreacted gas and reaction by-products, wherein the tantalum source adsorbing process, the first purge process, the reaction source supplying process, and the second purge process are repeated.

14. The method in claim 13 , wherein, during adsorbing the tantalum source, TaCl 5 is used as a precursor gas, and the precursor gas including. Ar gas flows at a flow rate of approximately 100 sccm to approximately 3,000 sccm for approximately 1 second to approximately 10 seconds.

15. The method in claim 13 , wherein, during performing the first purge process, N 2 gas or Ar gas flows for approximately 1 second to approximately 10 seconds.

16. The method in claim 13 , wherein, during supplying the reaction gas, O 3 gas or O 2 gas flows for approximately 1 second to approximately 10 seconds.

17. The method in claim 13 , wherein, in the second purge process, N 2 gas flows for approximately 1 second to approximately 10 seconds.

18. The method in claim 1 , wherein the second dielectric layer has a thickness no more than approximately 10 Å.

19. The method in claim 1 , wherein the first dielectric layer is thicker than the second dielectric layer.

20. The method in claim 19 , wherein a total thickness of the first to third dielectric layers ranges from approximately 100 Å to approximately 150 Å.

21. The method in claim 1 , wherein the lower electrode and the upper electrode comprise a metal.

22. The method in claim 21 , wherein the metal comprises one selected from the group consisting of TiN, Ru, Pt, Ir, and HfN, or a combination thereof.

23. The method in claim 1 , wherein the lower electrode has a cylindrically-shaped portion.