Design and fabrication of a novel compact RF MEMS series capacitive switch with reduced warping

Abstract This paper presents a novel compact RF MEMS series capacitive switch designed to address the common issues of severe warpage and excessive size in cantilever switches. Using SolidWorks, COMSOL Multiphysics, and HFSS as simulation tools, this paper designs an integrated structure combining the upper electrode with the signal bridge, along with a composite beam featuring an arc-shaped SiO flanged clamped beam and Au cantilever. The switch has overall dimensions of 229 µ m in length and 106 µ m in width. Fabrication results demonstrate low switch warpage while achieving series capacitive configuration and compact dimensions. Simulations reveal that the annular defect structure on the upper electrode reduces actuation voltage, with switch isolation exceeding 21.5 dB and insertion loss below 0.65 dB in the 25 GHz band. Both simulation and experiments indicate that biaxial residual stress exerts the most significant influence on composite structure actuation voltage compared to structural stress. The simulated actuation voltage without residual stress measures 28.8 V, whereas that of the fabricated prototype is approximately 100 V. This switch is suitable for terahertz intelligent metasurfaces and applications requiring minimized switch deformation.