Quantification of Uncertainty in Creep Failure of RF-MEMS Switches

Abstract

We present simulations of the failure of radio-frequency micro-electro-mechanical systems switches due to diffusional creep that include the quantification of uncertainty in the geometry, material parameters, and residual stress. The switch is modeled as an Euler-Bernoulli beam that is actuated electrostatically in a fluid medium. The fluid damping is modeled by a squeeze-film model and the beam model incorporates stretching nonlinearity in addition to Coble creep. The resulting nonlinear dynamic model is solved using a Ritz-Galerkin-based modal expansion and explicit time integration. The focus of this paper is on the effect of creep as a failure mechanism and the implications of uncertainty in the device geometry, material parameters, and boundary conditions. The degradation of the device performance is evidenced by decreases in the pull-in voltage, the pull-out voltage, and the impact velocity. We find that the variability in the experimentally measured pull-in voltage is accounted for by the inclusion of uncertainty in the material and geometric properties.