Patterned film effects on the adhesion of Al/TiN barrier using fracture-energy based finite element analysis

The interfacial adhesion of thin films between Al metal and TiN barrier is one of the major concerns dominating the mechanical reliability of semiconductor devices. The measured accuracy of cracking energy for stacked films with a nanoscale order is arduous to preserve because of the uncertainty in specimen preparations and instrumental operations. Consequently, the present research proposes a robust estimation of interfacial cracks using simulation-based methodologies to meet the requirement for mechanical designs in multi-level interconnected systems of electronic devices. According to the framework of the four-point bending test (4-PBT), the interfacial fracture energy of Al/TiN films is predicted via finite element analysis (FEA), combined with the J-integral method and modified virtual crack closure technique (VCCT). The foregoing simulated approaches are also verified by related analytical solutions and experimental data. Moreover, the effects of several patterned types of metal lines underneath the Al/TiN interface with various embedded cracks are analyzed. The primary results highlight a significant increase in the energy release rate (G) induced by the passing of a crack along the interface of Al/TiN films through the region below a metal line with a high degree of hardness. Dielectrics with a lower modulus would have the capacity to restrain progressive crack growth. Thus, a high G is expected to drop, as simultaneously demonstrated by the present simulated methodologies.