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.