Metal-metal oxide etch stop/barrier for integrated circuit interconnects
View Patent ↗Described is a method and apparatus for forming interconnects with a metal-metal oxide electromigration barrier and etch-stop. In one embodiment of the invention, the method includes depositing a metal layer on the top of a planarized interconnect layer, the interconnect layer having an interlayer dielectric (ILD) with a top that is planar with the top of an electrically conductive interconnect. In one embodiment of the invention, the method includes reacting the metal layer with the ILD to form a metal oxide layer on the top of the ILD. At the same time, the metal layer will not be significantly oxidized by the electrically conductive interconnect, thus forming a metal barrier on the electrically conductive interconnect to improve electromigration performance. The metal barrier and metal oxide layer together comprise a protective layer. A second ILD may be subsequently formed on the protective layer, and the protective layer may act an etch-stop during a subsequent etch of the second ILD.
1. An apparatus, comprising:
a first ILD;
an interconnect within the first ILD, the interconnect having a top surface planarized to a top surface of the first ILD;
a protective layer on the top surface of the interconnect and on the top surface of the first ILD, the protective layer including a metal oxide portion covering the top surface of the first ILD and an electromigration barrier covering the top surface of the interconnect, wherein the metal oxide portion protrudes below a plane defined by the top surface of the interconnect; and
a second ILD on at least the metal oxide portion of the protective layer, wherein the second ILD is in direct contact with the protective layer.
2. The apparatus of claim 1 , wherein the protective layer is to act as an etch-stop during etching and cleaning of the second ILD.
3. The apparatus of claim 1 , wherein the electromigration barrier comprises a metal and is to improve electromigration of the interconnect.
4. The apparatus of claim 1 , wherein the first ILD portion comprises an oxide material.
5. The apparatus of claim 1 , wherein the first ILD portion comprises a material selected from the group consisting of SiO 2 , SiOF, and CDO.
6. The apparatus of claim 1 , wherein the electromigration barrier covering the interconnect comprises a material selected from the group consisting of cobalt, aluminum, tantalum, chromium, and titanium.
7. The apparatus of claim 1 , wherein the protective layer has a thickness between approximately 10 Å to 100 Å.
8. An apparatus, comprising:
a substrate;
an interconnect layer overlying the substrate, the interconnect layer including an electrically conductive interconnect having a top surface planarized to a top surface of a first ILD;
a protective layer on the interconnect layer, the protective layer including a metal oxide portion covering the first ILD and an electromigration barrier covering the interconnect, wherein the metal oxide portion protrudes below a plane defined by the top surface of the interconnect;
and
a second JLD on at least the metal oxide portion of the protective layer.
9. The apparatus of claim 8 , wherein the protective layer is to act as an etch-stop.
10. The apparatus of claim 8 , wherein the electromigration barrier comprises metal and is to improve electromigration of the interconnect.
11. The apparatus of claim 8 , wherein the first RD comprises an oxide material.
12. The apparatus of claim 8 , wherein the electromigration barrier covering the interconnect comprises a material that can react, on contact, with an oxide material to form metal oxide.
13. A semiconductor device comprising:
a first interconnect layer including a first ILD and an electrically conductive interconnect within the first ILD;
a protective layer on the first interconnect layer, the protective layer including a metal oxide layer covering the first ILD and an electromigration barrier covering the interconnect, wherein a bottom surface of the metal oxide layer protrudes below a plane defined by a top surface of the interconnect; and
a second interconnect layer including a second ILD and an unlanded via within the second ILD, the unlanded via electrically connected to the interconnect, wherein at least a first portion of the second ILD is in direct contact with the metal oxide layer and at least a second portion of the second ILD is in direct contact with the electromigration barrier.
14. The device of claim 13 , wherein the protective layer and the second ILD have different etching properties.
15. The device of claim 13 , wherein the protective layer has a thickness between approximately 10 Å to 100 Å.
16. The device of claim 13 , wherein the first ILD contains oxygen.
17. The device of claim 13 , wherein the electromigration barrier comprises a metal material that can react, on contact, with an oxide material to form metal oxide.
18. The device of claim 17 , wherein
the metal material comprises a material selected from the group consisting of cobalt, aluminum, tantalum, chromium, and titanium; and
the metal oxide layer comprises one of cobalt oxide, aluminum oxide, tantalum oxide, chromium oxide, or titanium oxide.
19. The device of claim 13 , further comprising:
a substrate beneath the first ILD; and
a conductor within the substrate electrically connected to the interconnect.