Patent ID: 7223683

Claim:
A method of forming a plurality of bumps on a wafer having an active surface, wherein the wafer further includes a plurality of bonding pads formed on the active surface and a passivation layer formed on the active surface that exposes the bonding pads through passivation openings, the method comprising the steps of: forming a first dielectric layer over the active surface of the wafer wherein the first dielectric layer has a plurality of first openings and second openings exposing the bonding pads and portions of the passivation layer respectively; forming a first electrically conductive layer over the first dielectric layer, the bonding pads and the portions of the passivation layer exposing through the second openings; removing portions of the first electrically conductive layer to form a patterned first electrically conductive layer covering the first dielectric layer, the bonding pads and the portions of the passivation layer exposing through the second openings; forming a second dielectric layer with third openings over the first dielectric layer and the patterned first electrically conductive layer, wherein the third openings expose portions of the patterned first electrically conductive layer disposed in the second openings and the portions of the patterned first electrically conductive layer exposed out of the second dielectric layer serve as bump pads and are electrically connected to the bonding pads through the patterned first electrically conductive layer; forming a second electrically conductive layer over the second dielectric layer and the bump pads; forming a photo-resist layer with fourth openings on the second electrically conductive layer, and the fourth openings expose the second electrically conductive layer located over the bump pads; disposing a conductive material in the fourth openings located over the bump pads to form a plurality of bumps; removing the photo-resist layer; reflowing the bumps to form a plurality of reflowed balls securely attached to the bump pads; and after reflowing the bumps, removing the second electrically conductive layer to leave portions of the second electrically conductive layer covered by the reflowed balls to form a patterned second electrically conductive layer.