The effects of plasticity in thin copper layers on the interface fracture resistance in thin-film interconnect structures were explored using experiments and multiscale simulations. Particular attention was given to the relationship between the intrinsic work of adhesion, G_o, and the measured macroscopic fracture energy, G_c Specifically, the TaN/SiO_2 interface fracture energy was measured in thin-film Cu/TaN/SiO_2 structures in which the Cu layer was varied over a wide range of thickness. A continuum/FEM model with cohesive surface elements was employed to calculate the macroscopic fracture energy of the layered structure. Published yield properties together with a plastic flow model for the metal layers were used to predict the plasticity contribution to interface fracture resistance where the film thickness (0.25-2.5#mu#m) dominated deformation behavior. For thicker metal layers, a transition region was identified in which the plastic deformation and associated plastic energy contributions to G_c were no longer dominated by the film thickness. The effects of other salient interface parameters including peak cohesive stress and G0 are explored.
展开▼
