An interconnect structure and a method of forming an interconnect structure are disclosed. The interconnect structure includes a contact layer over a substrate, a dielectric layer over the contact layer, a silicide layer over the exposed portion of the contact layer, a barrier layer along sidewalls of the opening, an alloy layer over the barrier layer, a glue layer over the alloy layer, and a conductive plug over the glue layer, wherein the dielectric layer has an opening, and the opening exposes a portion of the contact layer.