Analysis and modeling of curvature in copper-based MEMS structures fabricated using CMOS interconnect technology

This paper addresses issues associated with building MEMS devices using conventional back-end-of-line (BEOL) materials and layers compatible with integrated circuit (IC) interconnect technology. Stresses inherent in these layers are of little significance for ICs, but when creating released structures, stress gradients become critical for optimum device operation. An analytical model to predict the curvature of multilayer MEMS cantilever beams has been developed. In addition, elemental analysis was performed in order to characterize the residual stress of individual films used in the analytical model. The analytical model fits the experimental data within 20%, and could be used as a guide for further design and process optimization of the MEMS devices.