Methods for producing interconnects in semiconductor devices
A method for forming metallization in a workpiece includes electrochemically depositing a second metallization layer on the workpiece comprising a nonmetallic substrate having a dielectric layer disposed over a substrate and a continuous first metallization layer disposed on the dielectric layer and having at least one microfeature comprising a recessed structure, wherein the first metallization layer at least partially fills a feature on the workpiece, where the first metallization layer is a cobalt or nickel metal layer, and wherein the second metallization layer is a cobalt or nickel metal layer that is different from the metal of the first metallization layer, electrochemically depositing a copper cap layer after filling the feature, and annealing the workpiece to diffuse the metal of the second metallization layer into the metal of the first metallization layer.
1. A method for forming metallization in a workpiece, the method comprising:
electrochemically depositing a second metallization layer on the workpiece comprising a nonmetallic substrate having a dielectric layer disposed over a substrate and a continuous first metallization layer disposed on the dielectric layer and having at least one microfeature comprising a recessed structure, wherein the first metallization layer at least partially fills a feature on the workpiece, wherein the first metallization layer is a cobalt or nickel metal layer, and wherein the second metallization layer is a cobalt or nickel metal layer that is different from the metal of the first metallization layer;
electrochemically depositing a metal cap layer after filling the feature; and
annealing the workpiece to diffuse the metal of the second metallization layer into the metal of the first metallization layer.
2. The method of claim 1 , wherein the first and second metallization layers are a single metal layer or a metal alloy layer.
3. The method of claim 2 , wherein the alloying metal of the metal alloy layer includes a transition or noble metal.
4. The method of claim 2 , wherein the alloying metal is selected from the group consisting of Ag, Au, Co, Ni, Pd, and Pt.
5. The method of claim 1 , wherein the first metallization layer is a seed layer.
6. The method of claim 1 , wherein the second metallization layer partially fills the feature and further comprising electrochemically depositing a third metallization layer to further partially or completely fill the feature before the cap layer is applied.
7. The method of claim 1 , wherein the annealing of the workpiece is carried out in a controlled manner to limit diffusion in the feature.
8. The method of claim 1 , wherein the annealing of the workpiece is carried out to cause the diffusion uniformly throughout the feature.
9. The method of claim 1 , wherein the workpiece further includes a barrier layer between the dielectric layer and the first metallization layer.
10. The method of claim 1 , further comprising using CMP to expose an upper surface of the workpiece.
11. The method of claim 1 , wherein the first metallization layer is a conformal layer.
12. The method of claim 1 , further comprising annealing the workpiece prior to deposition of the second metallization layer to reflow the first metallization layer.
13. The method of claim 1 , wherein the second metallization layer is a conformal layer.
14. The method of claim 1 , further comprising annealing the workpiece prior to deposition of the second metallization layer to reflow the first metallization layer.