Prevention of electromigration-induced Cu pad dissolution by using a high electromigration-resistance ternary Cu–Ni–Sn layer

Electromigration-induced Cu dissolution occurred at serious levels on the Cu pad under 104 A/cm2 current-stressing for 20 h at 160 °C. A high electromigration-resistance (Cu, Ni)6Sn5 layer, which converted from a thin Ni layer on the Cu pad, effectively prevented the Cu pad from dissolving into the pure Sn bump under 104 A/cm2 current-stressing for 30 h at 160 °C.