Numerical and Experimental Investigation of Thermomechanical Deformation in High-Aspect-Ratio Electroplated Through-Silicon Vias

Abstract

In this paper we present the numerical and experimental analysis of thermomechanical deformation in high-aspect-ratio copper electroplated through-silicon vias (TSVs), which were fabricated by deep reactive ion etching, thermal oxidation, and bottom-up electroplating processes. Later, these TSVs were subjected to thermal cyclic loading of . Due to the significant mismatch in the coefficients of thermal expansion of silicon and copper, thermomechanical stress was generated at the copper–silicon interface. Detailed investigation of this stress is of prime importance as it is one of the main root-causes behind the crack formation and dielectric delamination at the interface. A three-dimensional finite element model of the copper-filled TSVs was built and simulation was performed to predict the theoretical distribution of thermomechanical deformation. A noncontact digital image speckle correlation technique was used for the in situ measurement of the thermal deformation and the thermomechanical stress. Thermomechanical shear strain at the copper–silicon oxide–silicon interface was found to be the significant deformation mode in these TSVs.