Molecular Dynamics Simulation of the Mechanical Properties of Ag–Cu Supersaturated Solid Solution for High-Density Interconnect Application

With the rapid advancement of the integrated circuit industry, electronic packaging technologies have played a pivotal role in shaping the modern information society. The relentless drive for lower costs, miniaturization, and high-level integration has spurred the emergence of three-dimensional (3D) integration, significantly enhancing overall circuit performance. However, conventional interconnection methods employing copper pillars and tin-based solder frequently led to the formation of brittle intermetallic compounds (IMCs) at the solder/substrate interface during reflow soldering, thereby posing serious reliability challenges.To address these challenges, solid-state bonding technologies have emerged as a promising alternative. Our research group recently developed a novel Ag–Cu supersaturated solid solution via magnetron sputtering, which shows great potential as a micro-bump bonding material. To evaluate its suitability for 3D integration, we employed molecular dynamics simulations to construct two models of the Ag–Cu supersaturated solid solution: a single-crystal tensile model and a diffusion bonding model. These were used to explore the mechanical behavior and interfacial diffusion characteristics of the supersaturated alloy. The results demonstrate that the Ag–Cu supersaturated solid solution exhibits excellent performance as a micro-bump material during the bonding process. The enhanced bonding behavior is primarily attributed to the lattice destabilization and elevated chemical potential induced by Cu supersaturation. These findings offer atomistic-level insights for the design of metastable alloys to achieve reliable solid-state interconnection in advanced electronic packaging.