Impact of material and microstructure on thermal stresses and reliability of through-silicon via (TSV) structures

Thermal stresses and microstructures of two TSV structures with different fabrication conditions have been investigated using the precision wafer curvature and synchrotron x-ray microdiffraction methods, providing the first direct observation of local plasticity in the TSVs. Results from this study show that the electroplating chemistry directly affects the Cu microstructure, which in turn controls stress relaxation and build-up of the residual stress during thermal cycling. The implications on via extrusion and device keep-out zone (KOZ) are discussed.