Reduced stress under bump metallization structure

An improved under bump structure for use in semiconductor devices is described. The under bump structure includes a passivation layer having a plurality of vias. The vias are positioned such that a plurality of vias are associated with (i.e., located over) each contact pad. A metal layer fills the vias and forms a metallization pad that is suitable for supporting a solder bump. Preferably the metal layer extends over at least portions of the passivation layer to form a unified under bump metallization pad over the associated contact pad. Each metallization pad is electrically connected to the contact pad through a plurality of the vias. The described under bump structures can be formed at the wafer level.