ELECTRICAL RELIABILITY OF Cu/Sn MICRO-BUMP IN WAFER LEVEL PACKAGING FOR BioMEMS DEVICES

Abstract

The electrical reliability of Cu/Sn micro-bump in wafer level packaging for advanced BioMEMS devices applications were systematically investigated during current stressing condition. After bump bonding, Cu 3 Sn and Cu 6 Sn 5 intermetallic phases were observed, and Cu 3 Sn formed and grew at Cu pillar/Cu 6 Sn 5 interface with increasing annealing and current stressing time. The kinetics of intermetallic compound growth changed when all Sn in Cu/Sn micro-bump was exhausted. The complete consumption time of Sn phase in electromigration condition was faster than that in annealing condition. Under current stressing condition, intermetallic compound growth was significantly enhanced by current stressing where the growth rate follows a linear relationship with stressing time.