Effect of electromigration on intermetallic compound formation in line-type Cu/Sn/Cu interconnect

The line-type Cu/Sn/Cu interconnects were used to determine the growth kinetics of interfacial intermetallic compounds (IMCs) under current densities ranging from 5.0 × 103 to 1.0 × 104 A/cm2 at 100 and 150 °C, respectively. EM caused a polarity effect, i.e., the IMCs at the anode side were thicker than those at the cathode side. Compared with the aging specimens, the growth kinetics of the IMCs at the anode side during EM was significantly enhanced and still followed the t1/2 law. The growth behavior of the IMCs at the cathode side was complicated. A growth model of the IMC at the cathode side was established. When the initial interfacial IMCs were very thin, Jdis was minute compared with Jem + Jchem. The inward fluxes were larger than the outward fluxes, and thus the IMCs grew. After the IMCs reached a critical thickness, Jdis became lager than Jem + Jchem. The inward fluxes were less than the outward fluxes, and thus the IMCs decreased in thickness.