Effect of residual stress distribution on the performance of Micro-electromechanical systems for radio-frequency applications

The performance and reliability of radio-frequency microelectromechanical systems are critically dependent on the stiffness and stress state of their membranes. Although previous studies have demonstrated the potential of nanoindentation to extract elastic properties from simplified bilayer films, the combined effects of multilayer architectures, residual stress gradients, and device geometry in realistic RF-MEMS remain poorly understood. Here, we present the first systematic experimental framework that directly moves beyond average-stress-value measurement and couples depth-resolved Focused Ion Beam–Digital Image Correlation residual-stress profiling with high-resolution nanoindentation to analyze functional TiW/Au/TiW tri-layer MEMS cantilevers and membranes. Unlike prior bilayer model systems, this trilayer configuration is representative of industrial RF switch designs, enabling us to capture both tensile and compressive stress components across the thickness before and after annealing. Our results reveal geometry-independent stress redistribution mechanisms across the multi-layered system's thickness and demonstrate how controlled thermal treatments can tune stiffness, establishing device-level correlations among residual stress, elastic properties, and MEMS functionality, with direct implications for lowering actuation voltage and enhancing switching efficiency. • Depth-resolved residual stress profiling in TiW/Au/TiW MEMS structures • Coupling of FIB–DIC and nanoindentation for device-level stress analysis • Geometry-independent mechanisms of stress redistribution demonstrated • Annealing tunes stiffness and flatness with direct impact on RF performance • Framework enables predictive design of reliable, low-voltage RF-MEMS switches