Cross-sectional nanoindentation: A new technique for thin film interfacialadhesion characterization

Interfacial adhesion is becoming a critical material property for improving the reliability of multilayer thin film structures used in microelectronic s. Cross-sectional nanoindentation (CSN) is a new mechanical test especiall y designed for measuring the fracture toughness of thin film interfaces. In terfacial fracture is achieved by nanoindentation in the structure cross-se ction. A model based on the elastic plate theory has been developed to calc ulate numerically the interfacial critical energy release rate (G(ci)) for ceramic-ceramic systems from CSN test results. The model inputs are the thi n film elastic properties, thin film thickness, interfacial crack area and maximum thin him deflection during the test. Closed form analytical solutio ns, obtained for two limiting cases, are consistent with the numerical appr oach. This technique has been successfully applied to silicon nitride-silic on oxide thin films, commonly used as electrical isolators in microelectron ic devices. (C) 1999 Acta Metallurgica Inc. Published by Elsevier Science L td. Ali rights Reserved.