A semiconductor wafer has a top surface, a dielectric insulator, a plurality of narrow copper wires, a plurality of wide copper wires, an optical pass through layer over the top surface, and a self-aligned pattern in a photo-resist layer. The plurality of wide copper wires and the plurality of narrow copper wires are embedded in a dielectric insulator. The width of each wide copper wire is greater than the width of each narrow copper. An optical pass through layer is located over the top surface. A self-aligned pattern in a photo-resist layer, wherein photo-resist exists only in areas above the wide copper wires, is located above the optical pass through layer.