Method of manufacturing an interconnect structure by forming metal layers in mask openings
A method for manufacturing an interconnect structure includes providing a substrate structure including a substrate and a first dielectric layer on the substrate and having an opening for a first interconnect layer extending to the substrate, forming a first mask layer on a portion of the first dielectric layer spaced apart from the opening, forming a first metal layer filling the opening and covering a portion of the first dielectric layer not covered by the first mask layer, removing the first mask layer, forming a second dielectric layer on the first dielectric layer and on the first metal layer and having a trench for a second interconnect layer, the trench exposing a portion of the first metal layer; and forming a second metal layer filling the trench and in contact with the exposed portion of the first metal layer.
1. A method for manufacturing an interconnect structure, the method comprising:
providing a substrate structure including a substrate and a first dielectric layer on the substrate, the first dielectric layer having an opening for a first interconnect layer extending to the substrate underlying the first dielectric layer;
forming a first mask layer on a first portion of the first dielectric layer spaced apart from the opening;
forming a first metal layer filling the opening and covering the first dielectric layer uncovered by the first mask layer, wherein the first metal layer and the substrate together enclose a second portion of the first dielectric layer, and the second portion of the first dielectric layer has a top surface lower than the first portion of the first dielectric layer;
removing the first mask layer and exposing the first portion of the first dielectric layer;
forming a second dielectric layer on the exposed first portion of the first dielectric layer and on the first metal layer,
removing a portion of the second dielectric layer to form a trench for a second interconnect layer in the second dielectric layer, the trench exposing a portion of the first metal layer;
forming a second mask on the second dielectric layer; and
forming a second metal layer filling the trench and in contact with the exposed portion of the first metal layer.
2. The method of claim 1 , wherein forming the second metal layer in the trench comprises:
forming the second mask layer on a portion of a remaining second dielectric layer;
forming the second metal layer covering the trench; and
planarizing the second metal layer until an upper surface of the second metal layer is substantially flush with an upper surface of the remaining second dielectric layer.
3. The method of claim 2 , further comprising, prior to forming the second mask layer:
forming a second barrier layer on the remaining second dielectric layer, and on a bottom and sidewalls of the trench, the second mask layer is disposed on the second barrier layer.
4. The method of claim 2 , further comprising prior to forming the second mask layer:
forming a second barrier layer on the remaining second dielectric layer, and on a bottom and sidewalls of the trench, and
forming a second seed layer on the second barrier layer, the second mask layer is disposed on the second seed layer.
5. The method of claim 2 , wherein the first mask layer and the second mask layer each comprise a photoresist.
6. The method of claim 1 , wherein forming the second metal layer filling the trench comprises:
forming the second metal layer covering a remaining second dielectric layer; and
planarizing the second metal layer until an upper surface of the second metal layer is substantially flush with an upper surface of the remaining second dielectric layer.
7. The method of claim 1 , further comprising, prior to forming the first mask layer:
forming a first barrier layer on the substrate structure, the first mask layer being disposed on the first barrier layer; and
after removing the first mask layer, removing an exposed portion of the first barrier layer.
8. The method of claim 1 , further comprising, prior to forming the first mask layer:
forming a first barrier layer on the substrate structure; and
forming a first seed layer on the first barrier layer, the first mask layer being disposed on the first seed layer; and
after removing the first mask layer, removing an exposed portion of the first seed layer and an exposed portion of the first barrier layer.
9. The method of claim 1 , wherein forming the first metal layer comprises an electro-plating process, and forming the second metal layer comprises an electro-plating process.
10. The method of claim 1 , wherein the first metal layer and the second metal layer each comprises copper.
11. The method of claim 1 , wherein:
the opening comprises a groove extending into the first dielectric layer and one or more through holes below the groove, and
the first metal layer filling the opening is formed in the groove and in the one or more through holes below the groove.
12. The method of claim 1 , wherein the first metal layer is formed such that the first dielectric layer has a top surface lower than the first metal layer.
13. The method of claim 1 , wherein surface portions of the substrate exposed by the opening are separated by the second portion of the first dielectric layer.
14. The method of claim 1 , wherein the first metal layer and the second metal layer together enclose a portion of the second dielectric layer.
15. The method of claim 1 , wherein the first interconnect layer includes a damascene structure.
16. The method of claim 1 , wherein:
the first metal layer includes a first portion in the opening and a second portion in contact with the first portion and on a third portion of the first dielectric layer adjacent to the opening; and
the second portion of the first metal layer forms a lower portion of the second interconnect layer.