Three-Dimensional Simulation of the Thermo-Mechanical Interaction between the Micro-Bump Joints and Cu Protrusion in Cu-Filled TSVs of the High Bandwidth Memory (HBM) Structure

Based on High Bandwidth Memory (HBM) structure and taking into consideration the direct interconnection between the micro-bump and the end of the Cu-filled TSV, there is an interaction between the micro-bump joint and the Cu protrusion. To clarify this issue, in this study two geometric finite element models (i.e., 4-hi stack HBM structure and 8-hi stack HBM structure) are constructed and used to characterize the von Mises stress, volume fraction of plastic deformation region of the Cu-filled TSV, height of Cu protrusion and fatigue life of micro-bump joints with taking into account the interaction between the micro-bump joint and Cu protrusion. The simulation results manifest that micro-bump joints in 4-hi stack HBM model suffer larger average stress than those in 8-hi stack HBM model, and the volume fraction of plastic deformation region of Cu-filled TSV in the former model is also higher than that in the latter one. Interestingly, the height of Cu protrusion becomes equal at upper and lower ends of Cu-filled TSVs in upper TSV layers of 8-hi stack HBM model. From fatigue property point of view, 8-hi stack HBM model is superior to 4-hi stack HBM model.