Development and thermo-mechanical stress analysis of TSVs filling with Sn-based intermetallics

With the trend of commercialization of through-silicon vias (TSVs) in 3D integrated microsystems, new TSVs filling processes are developed to meet the requirement of low-cost fabricating of high-electrical performance and high-thermal reliability TSVs without any voids. In this paper, Sn-based IMCs are used as the filling materials for the formation of conductive path of TSVs. The Sn-based IMCs filling process is studied and the initial results are reported. Thermal-mechanical stress analysis of TSVs with different filling materials is performed through finite element analysis (FEA). The isotropic and anisotropic elastic property of silicon is considered in the FEA modeling. A static temperature ramp down analysis from 125°C to -40°C was carried out to simulate the maximum thermal stress state. The simulation results indicate that the TSVs filled with Cu₆Sn₅ and Ni₃Sn₄ exhibit lower thermal stress compared with solder TSVs and even Cu TSVs.