US Patent 7960269 Method for forming a double embossing structure

A method for fabricating a circuitry component comprises depositing a first metal layer over a substrate; forming a first pattern-defining layer over said first metal layer, a first opening in said first pattern-defining layer exposing said first metal layer; depositing a second metal layer over said first metal layer exposed by said first opening; removing said first pattern-defining layer; forming a second pattern-defining layer over said second metal layer, a second opening in said second pattern-defining layer exposing said second metal layer; depositing a third metal layer over said second metal layer exposed by said second opening; removing said second pattern-defining layer; removing said first metal layer not under said second metal layer; and forming a polymer layer over said second metal layer, wherein said third metal layer is used as a metal bump bonded to an external circuitry.