Development of cu/insulation layer interface crack extension simulation with crystal plasticity

A novel scheme for the evaluation of interface adhesion energy was examined by a detailed numerical simulation of interface crack extension. The effects of crystal orientation on the Cu/SiN interface adhesion strength of LSI was evaluated using the finite element method. Crack extension simulation was conducted with a model of the actual specimen used for the interface fracture test. The characteristics of elastic-plastic deformation, which changes significantly depending on crystal orientation, were taken into account in the model. With this scheme, the effect of orientation of single crystals on the maximum load Pmax was investigated under the condition of a constant bonding energy of the interface at the beginning of unstable crack propagation during the fracture test. The values of Pmax obtained with a number of different crystal orientations ranged over 179-311 N. The result indicates that the crack propagates more easily in the case that slip deformation of Cu near the interface starts with a low stress, as in the case of the (111) surface. It implies that the apparent interface adhesion strength represented by the load required to debond the interface strongly depends on Cu crystal orientation, because the amount of energy used for plastic deformation of the Cu crystal changes with crystal orientation near the interface.