Thin films constitute key elements in various multilayer electronic and optical devices such as integrated circuits, magnetic storage media and thermal sensing. One of the important parameters controlling the thermomechanical integrity and reliability of thin film systems is interface adhesion, which is characterized by two independent parameters: the interface strength and the interface fracture toughness. Laser-induced spallation methods have been developed to quantify these thin film interface adhesion parameters. The research presented in this dissertation involves developing new numerical methods to analyze a dynamic adhesion experiment that uses laser-induced stress wave to achieve a stable interfacial crack growth. Direct comparison between computational and experimental results is made to extract the interfacial fracture toughness.;A novel numerical method based on the combination of spectral and finite element scheme is presented to investigate the laser-induced edge delamination of patterned thin films. Spectral treatment for the substrate is based on the Fourier series representation of boundary elastodynamic equations, while an explicit finite element model is used to capture wave propagation in the thin film. Cohesive elements are introduced along the fracture plane to simulate the failure initiation and debonding process. The important role of the inertia on the crack extension and the appearance of the mixed-mode failure are demonstrated by observing the traction stress evolutions at various points along the bond line. Parametric studies on the effect of film thickness, interface fracture toughness, loading pulse on the debonding process are performed. Detailed study of the thin film edge delamination suggests a new specimen geometry that incorporates a weak adhesive layer made of high density material to exploit the inertial forces to better control crack propagation.;A significant obstacle limiting the application of the 2D hybrid spectral/finite element is its computational cost. To overcome such challenge and to support the laser spallation experiments in extracting the fracture toughness values, we develop a numerical scheme based on the combination of a nonlinear beam model to capture the elastodynamic response of the thin film and a cohesive failure model to simulate the interface. The accuracy of the model is assessed through a comparison with the results of a more complex 2D hybrid spectral/finite element scheme. Numerical results are then validated with experimental measurements of the interface crack evolution history using resistance gage technique. A major assumption in extracting the fracture toughness from the dynamic test is that most of the energy imparted in the pre-crack region of the film is channeled into the failure process. The reliability of this assumption is verified through a systematic parametric study of some of the key geometrical and loading quantities.;Various quasi-static adhesion measurement techniques have been developed for thin film systems including the peel, pull, blister, indentation and four-point bending tests. Despite their limitations, which are related to either time consuming sample preparation process or complicated data interpretation, these methods are still extensively used among industrial and academic community. In the last part of this dissertation, the four-point bend technique is employed and served as a baseline study to validate the dynamic test results. The quasi-static experiment is performed at a slow loading rate ca. 100 nm/s whereas the laser-induced stress wave loads the specimens at a high strain rate ca. 107/s in the dynamic test. Comparison results obtained from dynamic and quasi-static tests reveals the influence of loading rate on the interface fracture toughness.
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