Design And Optimization Of The Electrostatic Repulsive-force Based RF MEMS Switches

RF MEMS switch has been widely used in the RF MEMS field due to itsadvantages, such as little size, low power consumption, fast response time andeasily integrated with the IC circuit. RF MEMS switch has a big applicationfield including satellite communications, radar systems and electronics. Theelectrostatic capacitive RF MEMS switch is widely studied in these years.However, the industrialization is not realized. Thereinto, the dielectric chargingis generally recognized as the major failure in the electrostatic capacitive RFMEMS switches. In order to solve the dielectric charging problem, many effortshave been made from the research groups worldwide and various effectiveapproaches have also been developed. However, these methods are not optimal,they can control the charge accumulation to some extent, but cannot overcomethe stiction problem from the source.In the electrostatic capacitive RF MEMS switch, a huge electric field will beformed across the dielectric layer, a number of charges in the leakage current were captured by the traps. Thus the huge electric field is the main reason of thedielectric charging. In this paper, a novel electrostatic repulsive-force based RFMEMS switch was proposed to eliminate the huge electric field and decrease thedielectric charging. The main research works are as follow:(1) Analyze the failure of the electrostatic capacitive RF MEMS switch.Comparing the advantages and disadvantages of various approaches. Study thedevelopment status of the RF MEMS switch.(2) Introduce the basic conception and the operating mechanism of theelectrostatic repulsive-force. Analyze the reliability issue of the proposed RFMEMS switch. Introduce the finite element simulation software COMSOLMultiphysics, and demonstrate the feasibility.(3) Simulate and analyze the relationships between the maximumdisplacement and the structural parameters, such as movable electrode length,width and thickness, the fixed electrode width and thickness, horizontal distance,initial gap. The simulation results show that the relationships amongdisplacement and movable electrode length and initial gap are subject to thelinear relationship. The relationship between the displacement and the movableelectrode width and thickness are subject to the exponential relationship. Thedisplacement is largest, when the horizontal distance is3μm. In addition, thewidth and the thickness of the fixed electrodes have no obvious influence on thedisplacement value. (4) Design the new structures by modifying the elasticity coefficient ofstructure, the number of electrostatic repulsive-force units and the number offixed electrodes units. Investigate the relationship of these new structures. Atlast, design the manufacturing process and the processing maps of theelectrostatic repulsive-force based RF MEMS switch.