Rapid determination of stress factors and absolute residual stresses in thin films

Abstract

A methodology is presented that allows the determination of experimental stress factors in thin films on the basis of static diffraction measurements. The approach relies on the characterization of thin films deposited on a monocrystalline substrate serving as a mechanical sensor. Rocking-curve measurements of the symmetrical reflections of the substrate are used to determine the substrate curvature and subsequently the macroscopic stress imposed on the film. The elastic strain in the film is determined by lattice-spacing measurement at different sample tilt angles. The calculated experimental stress factors are applied to thin films deposited on other types of substrates and are used to determine the absolute magnitude of the residual stress. The approach is applied to nanocrystalline TiN and CrN thin films deposited on Si(100) and steel substrates, characterized using a laboratory-type θ/θ goniometer.