US Patent 7656045 Cap layer for an aluminum copper bond pad

A bond pad for an electronic device such as an integrated circuit makes electrical connection to an underlying device via an interconnect layer. The bond pad has a first layer of a material that is aluminum and copper and a second layer, over the first layer, of a second material that is aluminum and is essentially free of copper. The second layer functions as a cap to the first layer for preventing copper in the first layer from being corroded by residual chemical elements. A wire such as a gold wire may be bonded to the second layer of the bond pad.