Modeling of Frequency Shift in RF-MEMS Switches Under Residual Stress Gradient

Residual stress gradient is unavoidable in thin-film based devices such as radio frequency (RF) micro electro mechanical systems (MEMS) switches. In this paper residual stress gradient is modelled which affect the frequency shift in RF-MEMS switches. Curvature of thinfilms are measured experimentally and then residual stress gradient is modelled analytically and using finite element modeller (FEM). A comparison between analytical model and FEM has been carried out by introducing the initial upward curvature due to residual stress in the model. Beams under residual stress gradient change the pull-in voltage and shows frequency shift which points out that underestimating such effects can lead to inaccurate design and analysis of RF-MEMS switches and subsystems.