BRIDGE TYPE AND CANTILEVER TYPE MEMS SWITCH STRUCTURES

MEMS (Micro-Electro-Mechanical Structures) switches are devices used to achieve a short or open circuit by mechanical movement of a specific component of the device. The mechanical movement of the component could be accomplished in different ways: electrostatic, magnetostatic, piezoelectric or thermal designs were used to obtain the displacement, but, finally, only first solution (electrostatic) shows a reliability good enough to be take into account [1]. In the last two decades RF MEMS switches have been becoming increasingly attractive for different application areas, like radar systems for defence applications, automotive radars, satellite communication systems, wireless communication systems or instrumentation systems mainly due to their advantages (very low insertion loss, very high isolation, near-zero power consumption, intermodulation products and very low cost) over their counterparts (pin diodes or FET). A major advantage represents the possibility of monolithically batch fabrication when they are used as system components in an integrated RF system, which means that the overall system cost become cheaper than the system where is used as a switching component that requires hybrid assembly [1, 2]. This paper presents preliminary theoretical and experimental results obtained by our group in this field. The main goal of this work was to develop a reliable method for switch manufacturing which could be integrated with other RF MEMS devices (filters or antennas). Two different structure types were analysed: bridge and cantilever. For each of these structures were taken into account different length (from 600μm up to 900μm for bridge type and from 750μm to 1150μm for the cantilever type) and different actuation pads size in order to analyse the actuation voltage vs. pads size and to compare the theoretical with the experimental results.