Holding time effect on mechanical properties and protrusion behaviors of through silicon via copper under various annealing processes

Abstract

The thermomechanical reliabilities of TSV based structures are closely affected by the protrusion deformation, stress-strain constitutive behavior and microstructure evolution of TSV-Cu under various thermal loadings. In this study, the stress-strain constitutive curves of TSV-Cu under various annealing conditions considering holding time effect are acquired by the nanoindentation test and finite element (FE) reverse analysis. The yielding softening in stress-strain curves is found if the holding time is less than 90 min. However, the stable stress-strain curves are obtained as holding time exceeds 90 min. Furthermore, the mechanisms of softening and stability in stress-strain curves are revealed by observing the microstructure evolution of TSV-Cu with a wide range of holding time. In addition, the relationships among protrusion height, constitutive curves as well as microstructure parameter of TSV-Cu with different annealing holding time are built. This study provides an intrinsic insight on the correlations of deformation, constitutive curves, and microstructure for TSV-Cu annealing processes considering holding time effect.