Ruthenium metal feature fill for interconnects

1. A method for at least partially filling a feature in a substrate, the method comprising:

providing a substrate containing a feature;

depositing a ruthenium (Ru) metal layer to at least partially fill the feature; and

heat-treating the substrate to reflow the Ru metal layer in the feature,

wherein the Ru metal layer is deposited at a first substrate temperature and the heat-treating is performed at a second substrate temperature between 200° C. and 600° C. that is greater than the first substrate temperature.

2. The method of claim 1 , further comprising:

prior to depositing the Ru metal layer, forming a nucleation layer in the feature.

3. The method of claim 2 , wherein the nucleation layer is selected from the group consisting of Mo, MoN, Ta, TaN, W, WN, Ti, and TiN.

4. The method of claim 1 , wherein the Ru metal layer is deposited by atomic layer deposition (ALD), chemical vapor deposition (CVD), plating, or sputtering.

5. The method of claim 4 , wherein the Ru metal layer is deposited by CVD using Ru 3 (CO) 12 and CO carrier gas.

6. The method of claim 1 , wherein the substrate includes a dielectric layer and the feature is formed in the dielectric layer.

7. The method of claim 1 , wherein the heat-treating is performed in the presence Ar gas, H 2 gas, Ar gas and H 2 gas, or H 2 gas and N 2 gas.

8. The method of claim 1 , wherein the second substrate temperature is between 400° C. and 500° C.

9. A method for filling a feature in a substrate, the method comprising:

providing a substrate containing a feature;

depositing a conformal ruthenium (Ru) metal layer that fills the feature; and

heat-treating the substrate to reflow the conformal Ru metal layer in the feature,

wherein the conformal Ru metal layer has seam voids in the feature and the heat-treating seals the seam voids and increases the grain size of the conformal Ru metal layer in the feature, and

wherein the conformal Ru metal layer is deposited at a first substrate temperature and the heat-treating is performed at a second substrate temperature between 200° C. and 600° C. that is greater than the first substrate temperature.

10. The method of claim 9 , wherein the second substrate temperature is between 400° C. and 500° C.

11. The method of claim 9 , wherein the substrate includes a dielectric layer and the feature is formed in the dielectric layer.

12. The method of claim 9 , further comprising:

prior to depositing the conformal Ru metal layer, forming a nucleation layer in the feature.

13. The method of claim 12 , wherein the nucleation layer is selected from the group consisting of Mo, MoN, Ta, TaN, W, WN, Ti, and TiN.

14. The method of claim 9 , wherein the conformal Ru metal layer is deposited by atomic layer deposition (ALD), chemical vapor deposition (CVD), plating, or sputtering.

15. The method of claim 9 , wherein the conformal Ru metal layer is deposited by CVD using Ru 3 (CO) 12 and CO carrier gas.

16. The method of claim 9 , wherein the heat-treating is performed in the presence Ar gas, H 2 gas, Ar gas and H 2 gas, or H 2 gas and N 2 gas.

17. A method for at least partially filling a feature in a substrate, the method comprising:

providing a substrate containing a feature;

depositing a ruthenium (Ru) metal layer to at least partially fill the feature, wherein depositing the Ru metal layer pinches off a feature opening before the feature is filled with the Ru metal layer, thereby forming a void inside the feature;

removing excess Ru metal that caused the pinch off; and

thereafter, depositing additional Ru metal in the feature, wherein the Ru metal layer and the additional Ru metal are deposited by CVD using Ru 3 (CO) 12 and CO carrier gas.

18. The method of claim 17 , further comprising:

prior to depositing the Ru metal layer, forming a nucleation layer in the feature, wherein the nucleation layer is selected from the group consisting of Mo, MoN, Ta, TaN, W, WN, Ti, and TiN.

19. The method of claim 17 , wherein the removing the excess Ru metal includes a planarization process.