In Situ Atomic-Scale Investigation of Electromigration Behavior in Cu–Cu Joints at High Current Density

Electromigration (EM) poses significant challenges to the reliability of miniaturized devices, particularly three-dimensional integrated circuits (3DICs) operating under high current densities. The EM phenomenon results from atomic-scale mechanisms involving momentum transfer between electron carriers and atoms. In this study, high-resolution transmission electron microscopy (HRTEM) was employed to investigate the atomic-scale behavior of EM in Cu-Cu joints. The analysis revealed that EM initially induced slip along various crystallographic planes, which gradually evolved into a stable slip along specific orientations, dominating the failure. This anisotropic atomic transport led to progressive degradation at the Cu-Cu bonding interface, including void formation and microstructural evolution. This interface depletion has been identified as a critical factor influencing the reliability of 3DIC packaging. Results emphasized the need for optimizing interconnect and interface properties to mitigate EM-induced failures, which is relevant to the development of high-power semiconductor technologies.