Low-temperature hybrid bonding with high electromigration resistance scheme for application on heterogeneous integration

The novel low-temperature Cu/SiO2 hybrid bonding scheme using cluster-Ag passivation has been proposed in this study for the heterogeneous integration application. With the addition of cluster-Ag passivation layer, electromigration and reliability of hybrid bonding structure have been investigated for the first time, indicating negligible deterioration of electrical performance in the bonding structure after applying 107 A/cm2 current density for over 2000 h. The bonding mechanism of cluster-Ag passivation has been explored by the analysis of HR-TEM, and the difference between cluster-Ag passivation and thin-film Ag passivation has been discussed in detail. Based on an ultrathin cluster-Ag passivation layer, Cu-Cu bonding can be achieved at 70 ℃, showing high mechanical strength and good reliability. Therefore, the achievements reported in this paper realize Cu-Cu bonding and hybrid bonding with high quality and high reliability under ultra-low thermal budget, paving the way for the development of next-generation heterogeneous integration and three-dimensional integrated circuits (3DIC) technologies.