Characterization of film interface integrity through scanning acoustic microscopy

The functional characteristics of a thin film/coating depend critically upon its interface characteristics and adhesion to the substrate. However, reliable assessment of interface characteristics has remained a complex problem. Interface integrity is one such characteristic that is of critical importance to thin film characterization, failure analysis and process development efforts. This paper presents the scanning acoustic microscope (SAM) as an effective tool for the characterization of thin film/substrate interface integrity as well as nondestructive subsurface imaging. The potential offered by the SAM as an important tool to be used in conjunction with indentation/fracture mechanics based studies of thin film adhesion is also presented. The application of innovative SAM based imaging techniques for the assessment of film integrity and damage in representative titanium nitride and polycrystalline diamond thin films is presented.