Crystal Plasticity-Based Modeling and Experimental Validation of the Influence of Microstructures and Grain Boundary Junction Types on the Cu-Cu Bonding Interface

Hybrid bonding is a technology receiving significant attention in 3D semiconductor packaging, enabling enhanced device performance by reducing vertical dimensions and increasing interconnect density [1]-[4]. To enhance the quality of hybrid bonding, reliable bonding at the Copper-to-Copper (CuCu) interface is crucial. This study investigates void closure and interfacing mechanisms at the bonding interface with experimental observations and Crystal Plasticity Finite Element Method (CPFEM) simulations. The experimental results have shown that the microstructure at the bonding interface has a significant impact on void formation and the interface morphology [16]. This study systematically analyzes void evolution under varying bonding conditions. Crystal plasticity-based Cu-Cu bonding simulations show that pressure plays a dominant role in void closure, particularly in grain boundary regions, with higher pressure conditions accelerating material flux-driven void elimination. Furthermore, the results highlight that the difference in slip systems due to grain orientation has a significant impact on the void closure process, as demonstrated in the experiment, showing various forms of Cu-Cu interface outcomes. These findings support the experimental observations of void formation at grain boundary interfaces and provide helpful insights into optimizing Cu-Cu hybrid bonding for improved bonding quality in 3D semiconductor packaging.