| 摘要 |
The present invention relates to a structure of bumps forming on an under bump metallurgy layer (UBM layer) and a method for making the same. The structure comprises a wafer, a UBM layer, a second photo resist and a bump. The wafer has a plurality of solder pads and a protection layer, and the protection layer covers the surface of the wafer and exposes parts of the solder pads. The UBM layer is disposed on the solder pads and the protection layer and has an undercut structure. The second photo resist is disposed in the undercut structure. The bump is disposed on the UMB layer. Whereby, the UMB layer will not be reacted with bump in a reflow process and the problem of stress concentration will be avoided so as to make the bump more stable.
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