Microstructure simulation and thermo-mechanical behavior analysis of Cu-filled through silicon vias (TSVs) using combined Monte Carlo and finite element method

Abstract

Grain characteristics of copper filler have an important influence on physical properties of through silicon vias (TSVs) in three-dimensional (3D) packaging. Due to the mismatch of coefficients of thermal expansion (CTE) between the copper and silicon, there exist obvious thermal stresses when the TSV structure is bearing thermal load. However, the elastic response characteristics of copper can be affected distinctly by the size, shape and orientation of copper grains in TSVs. These effects can not be ignored, especially for 3D ICs undergoing continuous miniaturization and increasing integration. In this study, the grain growth and evolution of a typical copper filler in the TSV structure is dynamically simulated and investigated by using Monte Carlo method (MCM), then the thermo-mechanical behavior of TSVs with considering the grain characteristics of copper filler is studied with combined MCM and finite element method (FEM), i.e., MC-FE method. Besides, the effects of grain evolution on the protrusion of copper filler in the TSV is also investigated. Simulation results are presented for providing more quantitative description and comprehensive understanding of the influences of microstructure evolution of copper filler on the thermo-mechanical behavior of Cu-filled TSVs.