Abstract: A novel under-bump metallization (UBM) structure for providing electrical communication is described. The UBM structure includes a plurality of metallic layers, which are deposited onto a bonding pad of a semiconductor device, such as a semiconductor chip. The UBM structure may be provided as an interface between the bonding pad and a solder bump deposited over the UBM structure. In one example, the UBM structure includes layers of nickel and copper in which nickel is the upper layer in contact with the solder bump and copper is the lower layer in contact with the bonding pad. The nickel layer is formed to include a downwardly depending perimeter portion, which serves as a cover to the copper layer of the UBM structure. Accordingly, the copper layer is shielded from contact with the solder material during the reflow process, thereby avoiding undesirable reactions between the copper and solder.

Abstract: A method for preventing lead precipitation during wafer processing is disclosed. The method includes singulating a semiconductor wafer having a plurality of solder bumps and applying cold deionized (DI) water to the semiconductor wafer during singulation. Application of the cold DI water reduces or prevents lead precipitation during the singulation process, and thereby reduces the presence of bump oxidation.