| abstract |
A barrier layer is deposited over a layer of passivation including in annopening to a contact pad created in the layer of passivation. A column of threenlayers of metal is formed overlying the barrier layer and aligned with the contactnpad and having a diameter that is about equal to the surface of the contact pad.nThe three metal layers of the column comprise, in succession when proceedingnfrom the layer that is in contact with the barrier layer, a layer of pillar metal, a layernof under bump metal and a layer of solder metal. The layer of pillar metal isnreduced in diameter, the barrier layer is selectively removed from the surface ofnthe layer of passivation after which reflowing of the solder metal completes thensolder bump of the invention. |