In situ investigation of failure mechanisms in TGV interconnect structures under electrical loading

Abstract With the trend towards high-frequency, high-power-density packaging, through-glass vias (TGV) are considered a promising alternative to TSVs. However, their reliability under high current density, a critical concern for practical application, remains insufficiently studied. This work systematically investigates the failure mechanisms of TGV interconnect structures under electrical loads. In-situ electromigration experiments were conducted on daisy-chain TGV samples at current densities of 2.3×10 5 , 2.8×10 5 , and 3.0×10 5 A/cm 2 , with real-time resistance monitoring and cross-sectional SEM analysis. Distinct failure modes were identified: at the lowest density, failure was dominated by RDL/glass interfacial delamination with negligible resistance change; at the medium density, electromigration became apparent, accelerating void nucleation/growth and causing a linear resistance increase; at the highest density, severe thermo-mechanical coupling led to glass cracking at the TGV-RDL corner and RDL plastic deformation, resulting in an accelerated resistance rise. Complementary electro-thermo-mechanical finite element simulations revealed significant current crowding at the TGV-RDL corners, with local current density exceeding that at the narrowest via cross-section. The combined temperature field and geometric features jointly determined the stress concentration locations. This study clarifies the failure mechanisms of TGV and provides insights for the reliable design of high-current-density glass interposer packages.