2012  •  

Modeling of Damage Mechanisms in Metal Contact RF MEMS Switches

Lead Presenter:

In the field of Microelectromechanical Systems (MEMS), metallic contact microswitches have shown great potential in radio frequency (RF) communications applications. Such applications include cell phones, phased array RADAR, base-station and defense applications, and satellite applications [1]. An electrostatically actuated metal contact RF MEMS switch has a low insertion loss, a high isolation, low power consumption, and high linearity as compared to solid state switches such as Field Effect Transistor (FET) switches and PIN diodes [2]. For applications such as these, a switch life time in excess of 10 billion cycles is necessary. However, the low reliability of the metal contacts has greatly limited the average life-time of these types of switches [3]. The modeling efforts presented in this poster explore two possible mechanisms that lead to damage to a metal contact during hot switching, the application of electrical potential over the contact while the switch is opening or closing. An electrical current overshoot mechanism is explored using a circuit model that simulates current running through the contact while the switch in closing. The results of this model suggest that although an electrical current overshoot is theoretically present, the magnitude of the overshoot is not likely to cause extraneous contact damage. A thermal-electrical-mechanical coupling mechanism is explored using the finite element method to model a metal contact in the closed state. The results of this model provide a fundamental characterization of the interaction of the thermal, electrical, and mechanical domains of the MEMS switch contact. Together, these two modeling efforts provide greater understanding of the damage mechanisms in metal contact RF MEMS switches.