Fracture patterns in thin films and multilayers

Abstract

ABSTRACTWhile there are many stress relief mechanisms observed in thin films, excessive residual and externally applied stresses cause film fracture. In the case of tensile stress a network of through-thickness cracks forms in the film. In the case of compressive stress thin film buckling is observed in the form of blisters. Thin film delamination is an inseparable phenomenon of buckling. The buckling delamination blisters can be either circular, straight, or form periodic buckling patterns commonly known as telephone cord delamination morphology.While excessive biaxial residual stress is the key for causing thin film fracture, either in tension, or compression, it is the influence of the external stress that can control the final fracture pattern. In this paper we consider phone cord buckling delamination observed in compressed W/Si and TiWN/GaAs thin film systems, as well as spiral and sinusoidal though-thickness cracks observed in Mo/Si multilayers under 3-point high-temperature bending in tension.