Dissolution of substrates in line-type Cu/Sn/Cu and Cu/Sn/Ni interconnects under current stressing

The line-type Cu/Sn/Cu and Cu/Sn/Ni interconnects were used to investigate the dissolution of substrates under a current density of 2.0×10⁴ A/cm² at 150 °C for 50 h, 100 h and 200 h. For comparison, the line-type Cu/Sn/Cu and Cu/Sn/Ni interconnects were also aged at 150 °C for 50h, 100 h and 200 h. According to the experimental results, as the cathodes, no matter Cu or Ni, the dissolution of substrates in both Cu/Sn/Cu and Cu/Sn/Ni interconnects was in linear relationship with time. The dissolution rate of the Cu cathodes in Cu/Sn/Cu interconnects was approximately equal to that in Cu/Sn/Ni interconnects, indicating that the anode material had little effect on the dissolution of Cu cathodes. While in Cu/Sn/Ni interconnects, the Cu substrates dissolved more easily than the Ni substrates under the same conditions, i.e., Ni had a better electromigration (EM) resistance than Cu.