US Patent 7112523 Bumping process

A method of forming a plurality of bumps over a wafer mainly comprises the steps of providing a wafer having a plurality of bonding pads, forming an adhesive layer on the surface of the wafer to cover the bonding pads, patterning the adhesive layer to expose the bonding pads to form a patterned adhesive layer, forming a barrier layer and a wetting layer on the patterned adhesive layer and the surface of the wafer, removing the barrier layer and the wetting layer not covering the patterned adhesive layer, forming a plurality of bumps on the patterned wetting layer, and reflowing the bumps.