Residual stress effects on plastic deformation and interfacial fracture in thin-film structures

Residual stress in ductile thin films is shown to significantly affect the extent of film plasticity and interfacial fracture energy during debonding in thin-film structures. Specifically, the interfacial fracture resistance of a TaN/SiO2 interface in a thin-film structure containing an adjacent ductile Cu film with varying residual stress is compared to predictions from computational models. The fracture energy of the TaN/SiO2 interface increased by 50% for structures containing a Cu film in compression compared to similar structures with the film in tension. The effect of residual stress on interfacial adhesion is rationalized in terms of the onset of yielding within the Cu film, which affects the contribution from plastic energy dissipation to the total interface fracture energy.