Finite Element Modeling of the Effects of Copper Density on Bonding Area and Interfacial Stress in 1 μm Pitch Hybrid Bonding

Hybrid bonding is gradually becoming the mainstream technology for advanced packaging. Electrical connections and mechanical support are simultaneously formed at the bonding interface during the annealing process. Electrical performance is correlated with the Cu-Cu bonding area ratio, while mechanical strength is influenced by the SiO2-SiO2 interfacial stress. Both Cu expansion and stress are closely related to the pad size. In this work, we employ accurate modeling and comprehensive material properties to effectively simulate the interfacial behavior during annealing. The influence of Cu density on bonding area and interfacial stress at 1 μm pitch was systematically investigated using the finite element modeling (FEM). The simulation results provide critical guidance for optimizing bonding pad design and process control in hybrid bonding applications.