Si micro-cantilever sensor chips for space-resolved stress measurements in physical and plasma-enhanced chemical vapour deposition

Abstract

The control of extrinsic and intrinsic mechanical stresses in thin films is crucial. Stresses can limit the film performance e.g. by stress-induced delamination or undesired bending of film/substrate combinations; however, stresses can also be used to obtain functionality. Thus, understanding of stress-inducing mechanisms, correlations of stress with film synthesis parameters and controlling the sign and amplitude of stresses in thin films is important and a facile and reliable stress measurement method is necessary. Here, a stress measurement chip is presented which is based on the measurement of the residual overall film stress by a film-substrate combination curvature-based measurement technique. The novel Si-based cantilever sensor chip can measure residual stress in films from a few nanometers thickness up to several microns. Moreover, the sensor chips are applicable for determining the coefficient of thermal expansion, and for examining the film thickness homogeneity over large areas in a deposition system. They can be applied in physical vapor deposition and plasma-enhanced chemical vapor deposition processes with different geometrical and process-related boundary conditions. Exemplary results which were obtained with the sensor chips are discussed to demonstrate their easy applicability, accuracy, versatility, reliability, the thickness dependence of the residual stress and the homogeneity of SiOx films as well as the residual stress and the thermal expansion values of Al-Cr-N films.