Modeling and characterization of thin film polysilicon in thermally driven MEMS actuators

This paper analyzes a V-shaped thermal MEMS actuator for RF MEMS applications which has been fabricated using MetalMUMPs process from MEMSCAP Inc. and can withstand maximum actuation voltage of 15 V corresponding to 41.56 μm. The analysis is made through characterization of thin film polysilicon which is the source of producing heat in the thermal MEMS actuator. In addition, a lumped-element model with circuit elements is utilized to find the temperature in the polysilicon layer. The current-voltage characteristics of the thermal MEMS actuator is then simulated and compared against experimental data. The results show a very good agreement between experimental and simulated current-voltage characteristic curves. The developed model helps to design and fabricate V-shaped thermal MEMS actuators with high durability against higher actuation voltages which will enable them to exhibit higher displacements.