Metal cap integration by local alloying
AssigneeInternational Business Machines Corporation
InventorsPraneet Adusumilli, Alexander Reznicek, Oscar van der Straten, Chih-Chao Yang
Life of this patent
Estimating the term…
Abstract
A middle-of-line interconnect structure including copper interconnects and integral copper alloy caps provides effective electromigration resistance. A metal cap layer is deposited on the top surfaces of the interconnects. A post-deposition anneal causes formation of the copper alloy caps from the interconnects and the metal cap layer. Selective removal of unalloyed metal cap layer material provides an interconnect structure free of metal residue on the dielectric material layer separating the interconnects.
Claims20
A fabrication method for integrating electrically conductive caps on interconnects, comprising:
- obtaining a structure including a dielectric layer having a top surface, a plurality of open-ended trenches extending within the dielectric layer, and interconnects comprising copper within the trenches, the interconnects having top surfaces that are substantially coplanar with the top surface of the dielectric layer;
- depositing a metal cap layer on the structure such that the metal cap layer directly contacts the top surfaces of the interconnects at a plurality of interfaces, the metal cap layer comprising at least one of titanium, ruthenium and cobalt;
- subjecting the structure to thermal annealing to form metal alloy caps comprising copper from the interconnects and at least one of titanium, ruthenium and cobalt at the interfaces from a portion of the metal cap layer while a residual portion of the metal cap layer remains non-alloyed, and
- selectively removing the non-alloyed residual portion of the metal cap layer from the structure;
- wherein the metal alloy caps exhibit a stoichiometry of at least one part titanium, ruthenium or cobalt per one part of copper.
(canceled)
An interconnect structure, comprising:
- a dielectric layer having a top surface;
- a plurality of open-ended trenches extending within the dielectric layer;
- interconnects comprising copper within the trenches, the interconnects having top surfaces that are substantially coplanar with the top surface of the dielectric layer;
- a plurality of metal alloy caps for preventing electromigration, each of the alloy caps being integral with one of the interconnects and comprising an alloy of copper and at least one of titanium, ruthenium and cobalt.
Dependencies are inferred from the claim text.