Simulating the electromagnetic effects of thermally induced residual stresses in RF-MEMS switches

Radio frequency microelectromechanical systems (RF-MEMS) switches exhibit significant variations in the electrical, mechanical and thermal properties of their constituting materials after different microfabrication processes. During the cycle of thermal loading and unloading in the process of plasma etching, non-homogeneous tensile residual stress is formed in the microbeams of RF-MEMS Symmetric Toggle Switches (STS). This paper demonstrates the effect of these thermally induced residual stresses on the electromagnetic properties (S-parameters) of STS. In order to determine the radio frequency response of the switches, electromagnetic simulation is performed on a Finite Element Method (FEM) three dimensional model of the switch. The insertion and return losses with and without residual stresses are compared and the effect of thermally induced residual stress on them is verified.