Structure and method for low-stress concentration solder bumps

摘要

Low stress concentration solder bumps are created on a semiconductor wafer by the removal of metal oxides of under bump metallurgy, (UBM). The removal of the oxides from the circular edge of the UBM allow the solder of the solder bump to wet the sides of the UBM, mainly the plated portion, thereby resulting in a solder bump structure with a filled undercut. This results in a lower stress concentration solder bump structure. This solder bump structure is obtained after the solder bumps have been reflowed on the wafer.