Method for forming a titanium nitride layer

1. A method for forming a titanium nitride layer, comprising:

pre-heating a substrate, wherein the substrate is placed in an inert gas ambiance at a pre-heating pressure between 0.1˜3 torr; and

depositing a first TiN layer overlying the substrate, wherein the substrate is placed in a first reactive gas at least comprising NH 3 and TiCl 4 at a first reactive pressure of more than 5 torr and a first reactive temperature of more than 500° C.

2. The method as claimed in claim 1 , further comprising performing an annealing operation subsequent depositing the first TiN layer on the substrate, and the annealing operation is performed with the substrate disposed in NH 3 .

3. The method as claimed in claim 2 , wherein the annealing operation comprises an annealing pressure of more than 5 torr.

4. The method as claimed in claim 1 , wherein the NH 3 /TiCl 4 ratio of the first reactive gas is more than 1.

5. The method as claimed in claims 1 , further comprising, before depositing the first TiN layer overlying the substrate:

depositing a second TiN layer overlying the substrate, wherein the substrate is exposed to a second reactive gas at least comprising NH 3 and TiCl 4 with a second reactive pressure less than 1 torr and a second reactive temperature less than 500° C.

6. The method as claimed in claim 5 , further comprising, after depositing the second TiN layer and before depositing the first TiN layer:

performing an annealing operation in a NH 3 gas.

7. The method as claimed in claim 6 , wherein the annealing operation is with an annealing pressure between 1˜3 torr.

8. The method as claimed in claim 5 , wherein the NH 3 /TiCl 4 ratio of the second reactive gas is 3˜10.

9. The method as claimed in claim 1 , wherein the substrate comprises a bottom electrode of a capacitor and a dielectric layer disposed thereon, and the titanium nitride layer is formed on the dielectric layer.

10. The method as claimed in claim 1 , wherein the inert gas is N2 or Ar.

11. The method as claimed in claim 1 , wherein the pre-heating operation is carried out at a pre-heating temperature between 300˜500° C.

12. The method as claimed in claim 1 , wherein the pre-heating temperature is the same as the first reactive temperature of depositing the first TiN layer.

13. A method for forming a titanium nitride layer, comprising:

pre-heating a substrate, wherein the substrate is placed in an inert gas ambiance at a pre-heating pressure between 0.1˜3 torr;

depositing a first TiN layer on the substrate, wherein the substrate is placed in a first reactive gas at least comprising NH 3 and TiCl 4 with a first reactive pressure less than 1 torr and a first reactive temperature less than 500° C.;

performing first annealing operation with a first annealing pressure of between 1˜3 torr;

depositing a second TiN layer on the first TiN layer, wherein the substrate is placed in a second reactive gas at least comprising NH 3 and TiCl 4 with a second reactive pressure of more than 5 torr and a second reactive temperature of more than 500° C.; and

performing a second annealing operation with a second annealing pressure more than 5 torr.

14. The method as claimed in claim 13 , wherein the first annealing operation and the second annealing operation are performed in a NH 3 gas ambiance.

15. The method as claimed in claim 13 , wherein NH 3 /TiCl 4 ratio of the first reactive gas is 3˜10, and NH 3 /TiCl 4 ratio of the second reactive gas is more than 1.

16. The method as claimed in claim 13 , wherein the inert gas is N2 or Ar.

17. The method as claimed in claim 13 , wherein the pre-heating operation is performed at a pre-heating temperature between 300˜500° C.