Characterization of thermal stresses in through-silicon vias for three-dimensional interconnects by bending beam technique

Through-silicon via is a critical element for three-dimensional (3D) integration of devices in multilevel stack structures. Thermally induced stresses in through-silicon vias (TSVs) have raised serious concerns over mechanical and electrical reliability in 3D technology. An experimental technique is presented to characterize thermal stresses in TSVs during thermal cycling based on curvature measurements of bending beam specimens. Focused ion beam and electron backscattering diffraction analyses reveal significant grain growth in copper vias, which is correlated with stress relaxation during the first cycle. Finite element analysis is performed to determine the stress distribution and the effect of localized plasticity and to account for TSV extrusion observed during annealing.