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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 °C, the plastic deformation regions mainly locate in Cu pads, while spreading to Cu fillers under the thermal cycling with peak temperature 175 °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.