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, wherein the dielectric layer has an opening, the opening exposing a portion of 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.