The present invention provides a wafer structure having a plurality of bonding pad, an adhesion layer, a barrier layer, a wetting layer, a plurality of bump, a first passivation layer and a second passivation layer. The bonding pads are disposed on the active surface of the wafer and exposed by the first passivation layer. The second passivation layer is disposed on the first passivation layer and exposing the bonding pads. An adhesion layer is disposed on the bonding pad and covers a portion of the first passivation layer. The second passivation layer covers the first passivation layer and a portion of the adhesion layer. The barrier layer and the wetting layer are sequentially disposed on the adhesion layer and the bumps are disposed on the wetting layer.