Analysis of thin film stress measurement techniques

Residual stresses in several magnetron sputtered Mo thin films, with thicknesses from 100 nm to 1.60 mu m, were determined using double-crystal diffraction topography (DCDT), sin(2) psi, and the high-resolution X-ray diffraction technique (HRXRD). The Mo films had a range of microstructures that included random and polycrystalline, textured out-of-pIane, and textured in-plane. When the average biaxial stresses over the entire film thickness were determined for the films using the aforementioned techniques, the results were comparable in magnitude. However, the stresses determined with the substrate curvature technique, DCDT, were consistently smaller than those obtained with the sin(2) psi and HRXRD techniques. The difference may arise for several reasons. For example, the HRXRD and sin(2) psi measurements of a textured film may not be indicative of the mean film stress, and thus may differ from the curvature measurement. Also, substrate curvature techniques measure extrinsic stresses, or stresses that arise solely from the presence of the substrate. The techniques which analyze the film directly, such as sin(2) psi, and HRXRD, measure the extrinsic stresses and the intrinsic stresses that arise from defects or morphology changes within the film. The additional information that can be obtained from the depth-sensitive HRXRD technique concerning stress variations within thin films was also highlighted. (C) 1997 Elsevier Science S.A.