Investigating and optimizing Ion migration and degradation at Cu-SiO₂ interfaces in advanced electronics packaging

Through-Silicon vias (TSVs) and through-glass vias (TGVs), which are Cu channels through a substrate layer of Si or glass, are often used in advanced packaging to minimize the circuit footprint of interconnects. TSV/TGV optimization is crucial to fully enable 2.5D and 3D circuit integration, which rely on multi-die stacks within the same package. However, current TSV and TGV technology often face issues with Cu channel ion migration into the interposer and dielectric layers, as well as parasitic capacitance and conductance between vias. Our investigation focuses on these two problems, using a methodology consisting of density functional theory (DFT) in conjunction with ballistic-regime non-equilibrium Green's function (NEGF) theory as we consider TSV/TGV systems and interfaces that the industry will encounter when sub-μm via pitches move from theoretical to practicable. In this presentation, we will present our work and findings analyzing Cu channel ion migration across the Cu-dielectric interface through climbing-image nudged elastic band (CI-NEB) and ab initio molecular dynamics (AIMD) calculationations under externally-applied electric fields. Our study considers the Cu-SiO₂ interface degradation with and without the addition of barrier layers and how the degradation occurs at common failure points in traditional TSVs.