Copper-metallized integrated circuits having electroless thick copper bond pads

Abstract

A metal structure () for a contact pad of a semiconductor, which has interconnecting traces of a first copper layer (). The substrate is protected by an insulating overcoat (). The first copper layer of first thickness and first crystallite size is selectively exposed by a window () in the insulating overcoat. A second copper layer () of second thickness covers conformably the exposed first copper layer. The second layer is deposited by an electroless process and consists of a transition zone, adjoining the first layer and having copper crystallites of a second size, and a main zone having crystallites of the first size. The distance a void can migrate from the second layer is smaller than the combined thicknesses of the first and second layers. A nickel layer () is on the second copper layer, and a noble metal layer () is on the nickel layer.