Characterization of Electromigration-induced degradation in Micro Bumps Via On-Chip Embedded Temperature Sensors Under High Current Density

This study investigates electromigration-induced degradation in micro bumps through an integrated experimental and computational approach. Platinum thin-film temperature sensors were embedded within flip-chip specimens to enable real-time thermal monitoring. Internal package temperatures were measured using these sensors, with validation via infrared thermography, to quantitatively characterize Joule heating effects under high-current-density conditions. Cross-sectional SEM analysis of specimens subjected to accelerated current stressing revealed that electromigration drives two concurrent failure mechanisms in electro-thermal coupling environments: (1) void nucleation-propagating along IMC/solder boundaries, and (2) necking caused by accelerated solder consumption. A multi-physics modeling framework combining unified creep plasticity (UCP) constitutive laws with the J-integral fracture mechanics method was developed to simulate shear deformation evolution in micro bumps containing electromigration-induced voids. Computational results demonstrated that void propagation disrupts hydrostatic stress uniformity, inducing localized stress concentrations near solder-depleted regions. Crucially, solder consumption-induced voids exhibited higher stress intensification compared to IMC-interface voids, establishing a direct correlation between void topology and mechanical reliability degradation.