A semiconductor device having copper interconnecting metallization (111) protected by a first (102) and a second (120) overcoat layer (homogeneous silicon dioxide), portions of the metallization exposed in a window (103) opened through the thicknesses of the first and second overcoat layers. A patterned conductive barrier layer (130) is positioned on the exposed portion of the copper metallization and on portions of the second overcoat layer surrounding the window. A bondable metal layer (150) is positioned on the barrier layer; the thickness of this bondable layer is suitable for wire bonding. A third overcoat layer (160) consist of a homogeneous silicon nitride compound is positioned on the second overcoat layer so that the ledge (162, more than 500 nm high) of the third overcoat layer overlays the edge (150b) of the bondable metal layer. The resulting contoured chip surface improves the adhesion to plastic device encapsulation.