Three-dimensional simulation of the effects of Cu protrusion of Cu-filled TSVs on thermal fatigue behavior of micro-bump joints in 3D integration

A single-layered TSV structure model without micro-bump joints and a three-layered TSV structure model with micro-bump joints were constructed to simulate the changes of Cu plastic deformation regions and Cu protrusion of Cu-filled TSVs under different thermal cycling conditions, by means of finite element (FE) simulation. On the basis of strain energy theory, the effects of Cu protrusion of Cu-filled TSVs on thermal fatigue behavior of micro-bump joints were investigated. The simulation results manifest that under the thermal cycling with peak temperature 125 degrees C, the plastic deformation regions mainly locate in Cu pads, while spreading to Cu fillers under the thermal cycling with peak temperature 175 degrees C, and Cu protrusion height increases with increasing peak temperature. Significantly, it is found that the increase in Cu protrusion leads to the decrease in thermal fatigue life of micro-bump joints.