Patent ID: 9082762
Filing Date: 2015-07-14
Classification: H01L

Abstract:
1. A process for manufacturing an electromigration-resistant UBM Sn-rich Pb-free solder bump flip chip structure wherein said electromigration-resistant UBM structure consists essentially of a four-layer electromigration-resistant UBM structure or a three-layer electromigration-resistant UBM structure, and wherein said four layer structure consists essentially of, 1) an adhesion layer, 2) a Cu seed layer for plating, 3) a reaction barrier layer, and 4) a wettable layer for joining to said solder, and said three-layer structure is formed by applying to said structure, 1) an adhesion layer, 2) a reaction barrier layer, and 3) a wettable layer for joining to said solder, wherein said 4 layer UBM structure consists essentially of a Cu layer and said reaction barrier layer consists essentially of a Ni—Fe alloy or Cu applied to said Cu layer to eliminate or reduce electromigration.