A new method for measuring the residual stresses in multi-layered thin film systems

To meet different electrical or optical functionalities, thin films are often of multiple layers processed at high temperatures. Substantial residual stresses can therefore develop in such thin film systems due to the disparate thermal properties of the individual material layers. High stresses can lead to mechanical failure of the systems and thus understanding the residual stresses in thin film systems is important. This paper presents a systematic way to characterize the residual stresses in epitaxial, polycrystalline and amorphous layers by using X-ray diffraction (XRD) techniques. The single-point XRD pattern renders the stresses of crystalline layers and the scanning XRD gives the curvature of the whole film. Based on the newly-developed analytical model, the residual stresses of each layer can all be determined.