Importance

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Abstract

A semiconductor device having bump electrodes mainly comprises a specialized under bump metallurgy (UBM) applied to a chip with copper contact pads. Typically, the chip comprises a substrate and at least one copper contact pad on the substrate. A passivation layer is formed over the substrate and has an opening positioned over the al least one copper contact pad. The UBM includes a titanium layer, a first copper layer, a nickel-vanadium layer and a second copper layer. The titanium layer forms a closed-loop surrounding the opening of the dielectric layer. The first copper layer is formed over the titanium layer and the opening of the dielectric layer such that the first copper layer directly contacts the copper contact pad. The nickel-vanadium layer is formed on the first copper layer and the second copper layer is formed on the nickel-vanadium layer. A metal bump is provided on the UBM over the copper contact pad thereby forming a bump electrode. The UBM of the present invention is characterized by using the titanium layer with a closed-loop shape as the adhesion layer to significantly increase the adhesion between the UBM and the passivation layer, and using the first copper layer, which is directly contacted with the copper contact pad, to provide a better electrical performance.

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First Claim