The present disclosure describes an bonding pad formation method that incorporates an tantalum (Ta) conductive layer to block mobile ionic charges generated during the aluminum-copper (AlCu) metal fill deposition. For example, the method includes forming one or more interconnect layers over a substrate and forming a dielectric over a top interconnect layer of the one or more interconnect layers. A first recess is formed in the dielectric to expose a line or a via from the top interconnect layer. A conductive layer is formed in the first recess to form a second recess that is smaller than the first recess. A barrier metal layer is formed in the second recess to form a third recess that is smaller than the second recess. A metal is formed to fill the third recess.