a bumping process mainly comprises the steps of providing a wafer having a plurality of bonding pads , forming a patterned adhesive layer over the bonding pads , 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 .