Interfacial Crack Initiation and Delamination Propagation in Cu-filled TSV Structure by Incorporating Cohesive Zone Model and Finite Element Method

In the present work, the effect of SiO2 insulating layer with different thicknesses on stress distribution in Cu-filled through silicon via (TSV) structure is characterized by simulation for the first time. By incorporating cohesive zone model (CZM) with the finite element (FE) model, the crack initiation and delaminating propagation at the Cu/SiO2 interface at elevated temperature are studied extensively. Further, the effect of Cu pad with various thicknesses on interfacial crack delamination propagation in Cu-filled TSV has been simulated with CZM. The simulation results show that the presence of the SiO2 insulation layer can relieve stress concentration and thus decrease the fracture energy. However, increasing the thickness of insulation layer has a minor influence in reducing stress concentration. The propagation rate of a crack along the Cu/SiO2 interface decreases greatly once the crack initiates. The crack initiated at the opening of TSV prefers to propagate vertically and the thicker overlaying Cu pad leads to retardation of crack delamination propagation along the Cu/SiO2 interface.