A comparative study of a new microscale technique and conventional bending techniques for evaluating the interface adhesion strength in IC metallization systems

We developed a new microscale technique for evaluating the local interface adhesion in a thin film stack and we compared it with a conventional four-point bending technique. Using the microscale technique, the interface adhesion was estimated to be 3.0 J/m² by comparing experimental results with numerical simulation results for interface crack propagation behavior. The four-point bending technique was applied to the same interface and the interface adhesion was estimated to be 4.4 J/m² by experiment. However, this value is an overestimate because it includes the plastic deformation of epoxy resin used to fabricate the specimens. By eliminating the additional energy dissipated through plastic deformation of the epoxy resin close to the interface crack tip, the interface adhesion was evaluated to be 3.3 J/m². This value agrees well with that obtained using the microscale technique.