Patent ID: 8269345

Claim:
A bump contact for electrically connecting a conductor on a substrate and a contact pad on a semiconductor device mounted to the substrate, the bump contact comprising: a. an electrically conductive pillar having first and second extreme ends, the first end of the pillar being capable of effecting electrical contact and mechanical attachment of the pillar to the contact pad on the semiconductor device with the pillar projecting outwardly from the semiconductor device; b. a solder crown having first and second extreme ends, the solder crown being positioned in axial alignment with the pillar with the first end of the solder crown facing the second end of the pillar, the solder crown being reflowable at a predetermined temperature into effecting electrical contact and mechanical attachment by the second end thereof with the conductor on the substrate; and c. a diffusion barrier electrically and mechanically joining the first end of the solder bump to the second end of the pillar, the diffusion barrier resisting electro-migration into the first end of the solder crown by a selected chemical constituent of the pillar, the diffusion barrier comprising a control layer of material on the second end of the pillar, the material of the control layer being chosen from the group consisting of palladium, alloys of titanium-tungsten, and tantalum nitride.