Patent ID: 7271498
Filing Date: 2007-09-18
Classification: H01L

Abstract:
1. A wafer structure, comprising: a wafer having a plurality of bonding pads, wherein the bonding pads are disposed on an active surface of the wafer; a first passivation layer covering the active surface of the wafer, wherein the bonding pads are not fully covered by the first passivation layer; an under ball metallurgy (UBM) layer disposed on each of the bonding pads, wherein the UBM layer comprises a first metallic layer and a second metallic layer disposed on the first metallic layer, the first metallic layer permanently covering a portion of the first passivation layer, and the UBM layer above each of the bonding pads is detached from the others; a second passivation layer permanently disposed on the first passivation layer, wherein the second metallic layer of the UBM layer does not cover the second passivation layer, and the second passivation layer covers a peripheral portion of the first metallic layer, without covering the second metallic layer; and a plurality of bumps, disposed on the UBM layer.