Ruthenium metal feature fill for interconnects
A method is provided for at least partially filling a feature in a substrate. The method includes 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.
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;
heat-treating the substrate to reflow the Ru metal layer in the feature;
depositing additional Ru metal layer on the heat-treated Ru metal layer in the feature; and
heat-treating the additional Ru metal layer to reflow the additional Ru metal layer in the feature.
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 incomplete with gaps that expose the substrate in the feature.
4. 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.
5. The method of claim 1 , further comprising
prior to depositing the Ru metal layer, exposing the substrate to a treatment gas that increases a nucleation rate of the Ru metal layer in the feature.
6. The method of claim 5 , wherein the treatment gas includes nitrogen.
7. The method of claim 1 , wherein the Ru metal layer is deposited by atomic layer deposition (ALD), chemical vapor deposition (CVD), plating, or sputtering.
8. The method of claim 7 , wherein the Ru metal layer is deposited by CVD using Ru 3 (CO) 12 and CO carrier gas.
9. The method of claim 1 , wherein the substrate includes a dielectric layer and the feature is formed in the dielectric layer.
10. 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.
11. The method of claim 1 , wherein the Ru metal layer is deposited at a first substrate temperature and the heat-treating is performed at a second substrate temperature that is greater than the first substrate temperature.
12. The method of claim 11 , wherein the second substrate temperature is between 200° C. and 600° C.
13. 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
heat-treating the substrate to reflow the Ru metal layer in the feature.
14. The method of claim 13 , further comprising:
prior to depositing the Ru metal layer, forming a nucleation layer in the feature.
15. The method of claim 14 , wherein the nucleation layer is selected from the group consisting of Mo, MoN, Ta, TaN, W, WN, Ti, and TiN.
16. The method of claim 14 , wherein the Ru metal layer is deposited by atomic layer deposition (ALD), chemical vapor deposition (CVD), plating, or sputtering.
17. The method of claim 16 , wherein the Ru metal layer is deposited by CVD using Ru 3 (CO) 12 and CO carrier gas.
18. The method of claim 14 , 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.
19. The method of claim 13 , wherein the Ru metal layer is deposited at a first substrate temperature and the heat-treating is performed at a second substrate temperature that is greater than the first substrate temperature.
20. The method of claim 19 , wherein the second substrate temperature is between 200° C. and 600° C.