Plated metallization structures
The disclosed technology generally relates to forming metallization structures for integrated circuit devices by plating, and more particularly to plating metallization structures that are thicker than masking layers used to define the metallization structures. In one aspect, a method of metallizing an integrated circuit device includes plating a first metal on a substrate in a first opening formed through a first masking layer, where the first opening defines a first region of the substrate, and plating a second metal on the substrate in a second opening formed through a second masking layer, where the second opening defines a second region of the substrate. The second opening is wider than the first opening and the second region encompasses the first region of the substrate.
1. An integrated circuit device, comprising:
a substrate;
one or both of a first conductive barrier layer and a seed layer formed on a major surface of the substrate; and
a metallization structure comprising a first metal feature having top and side surfaces above the one or both of the first conductive barrier layer and the seed layer that are encapsulated by a second metal, wherein each of the first metal feature and the second metal is formed over the one or both of the first conductive barrier layer and the seed layer that are patterned to be laterally coextensive with the metallization structure, wherein the second metal has a conformal thickness profile characteristic of a plated layer across the top surface of the first metal feature, wherein a ratio of a thickness of the first metal feature to a thickness of the second metal is between about 0.5 and 1.5, and wherein the metallization structure forms a line elongated in a direction substantially parallel to the major surface of the substrate and has a thickness exceeding about 10 microns.
2. The integrated circuit device of claim 1 , wherein the metallization structure has a width which remains constant or decreases from a base portion towards an upper surface.
3. The integrated circuit device of claim 2 , wherein the second metal encapsulates the first metal feature and laterally extends outside of the first metal feature such that the metallization structure comprises a raised portion formed by the second metal encapsulating the first metal feature and further comprises a portion electroplated directly on the conductive barrier layer or the seed layer.
4. The integrated circuit device of claim 3 , further comprising a conductive via electrically contacting the raised portion through one of more dielectric layers formed over the metallization structure.
5. The integrated circuit device of claim 3 , wherein the first metal feature and the second metal are formed of different metals.
6. The integrated circuit device of claim 5 , wherein a second conductive barrier layer interposed between the first metal feature and the second metal encapsulates the first metal feature, wherein the second conductive barrier layer serves as a diffusion barrier for suppressing diffusion of atoms of the first metal feature.
7. The integrated circuit device of claim 6 , wherein the first metal feature comprises copper.
8. The integrated circuit device of claim 7 , wherein a third conductive barrier layer is interposed between the first metal feature and the substrate.
9. The integrated circuit device of claim 5 , further comprising a third conductive barrier layer interposed between the first conductive barrier layer and the first metal feature.
10. The integrated circuit device of claim 5 , wherein the metallization structure further comprises a third metal encapsulating the second metal and contacting the first conductive barrier layer or the seed layer.
11. The integrated circuit device of claim 1 , wherein the second metal encapsulates the first metal feature to form the metallization structure wider and thicker than the first metal feature.
12. The integrated circuit device of claim 11 , wherein the second metal has thicknesses over a top surface and side surfaces of the first metal feature that are about the same.
13. The integrated circuit device of claim 1 , wherein the metallization structure is formed at a single metallization level.
14. The integrated circuit device of claim 1 , wherein the first metal feature has a width which remains substantially constant or decreases from a base portion towards an upper surface.
15. The integrated circuit device of claim 1 , wherein the first metal feature has a width at an upper portion that is wider than a width at a base portion.
16. The integrated circuit device of claim 1 , wherein the first metal feature and the second metal comprise the same metal.
17. The integrated circuit device of claim 1 , wherein each of the first metal feature and the second metal contacts the same one of the first conductive barrier layer or the seed layer.
18. The integrated circuit device of claim 1 , wherein the first metal feature comprises gold or copper.
19. The integrated circuit device of claim 18 , wherein the second metal comprises a different one of gold or copper.