Stress-induced periodic fracture patterns

Residual and/or externally applied stresses in thin films can cause film fracture. In the case of compressive stress thin film buckling is observed in the form of delamination blisters, which can be either circular, straight, or form periodic buckling patterns commonly known as telephone cord delamination morphology. In the case of tensile stress a network of through-thickness cracks forms in thin films. Excessive biaxial residual stress is the key for causing thin film fracture, either in tension, or compression, although the influence of the external stress is also important. In this presentation we discuss phone cord buckling delamination observed in compressed W/Si and TiWN/GaAs thin film systems. Also, spiral and sinusoidal though-thickness cracks observed in Mo/Si multilayers under 3-point high-temperature bending in tension, and scratch-induced periodical cracks in W atomic deposited layers on Si wafers are considered