Electromigration polarity effect of Cu/Ni/Sn-Ag microbumps for three-dimensional integrated circuits

摘要

In this study, intermetallic compound (IMC) growth behavior in Cu pillar/Ni/Sn bumps was investigated under both annealing and current stressing conditions. An electromigration test was performed on the daisy-chain structure under the current stressing of 1.2×10⁵A/cm²at an ambient temperature of 150 °C. Ni₃Sn₄IMC formed at the interface between the Ni barriers and Sn after bonding. As the Ni₃Sn₄phase as the annealing time increased, causing micro-voids to form near the center of a joints. On the other hand, as the Ni₃Sn₄phase as the current stressing time increased, causing micro-voids to form near the cathode side of a joints. We believe that polarity effects are observed in microbumps.