a barrier layer is deposited over a layer of passivation including in an opening to a contact pad created in the layer of passivation . a column of three layers of metal is formed overlying the barrier layer and aligned with the contact pad and having a diameter that is about equal to the surface of the contact pad . the three metal layers of the column comprise , in succession when proceeding from the layer that is in contact with the barrier layer , a layer of pillar metal , a layer of under bump metal and a layer of solder metal . the layer of pillar metal is reduced in diameter , the barrier layer is selectively removed from the surface of the layer of passivation after which reflowing of the solder metal completes the solder bump of the invention .