Experimental Characterization of Electro-Thermo-Mechanical Coupling in Gold RF Microswitches

This paper analyses the multiple coupling occurring in some metallic microstructures electrostatically actuated in presence of thermal effect. Some relevant issues of basic procedures implemented to identify the relevant design parameters and the material properties of micro-electro-mechanical systems (MEMS) are preliminarily discussed. Temperature effects on the MEMS strain distribution in operating conditions are then investigated. Thermo-mechanical coupling is studied through some experiments performed on microbridge prototypes electrostatically actuated by comparing their behavior in case of superposed electro-thermal actuation and of thermal loading without electrostatic coupling. A detailed analysis is here performed to evaluate the role of the thermal stress upon the buckling of the microstructure and its effect on the deformed shape of the microbeam. Electro-thermo-mechanical coupling is therefore modeled and experimentally analyzed. Pull-in tests are used to detect some effects of mutual interaction between temperature and electrical actuation. The methodologies, here proposed, apply to several materials used in microfabrication, although experimental evidence described herein concerns some gold microbridges to be included in RF devices.