A Compliant MEMS Device for Out-of-Plane Displacements With Thermo-Electric Actuation

A MEMS actuator for micrometric displacements in the out-of-plane direction is proposed in this paper. The device is based on a compliant micromechanism composed of a thick layer of nickel and two thin layers of silicon nitride ensuring displacements in the out-of-plane direction. Its actuation is thermo-electrically performed, the polysilicon resistor encapsulated between the two thin silicon nitride layers is heated by Joule effect; the obtained thermo-mechanical deformation is therefore converted into an out of plane displacement thanks to the compliant mechanism realized in the device structure. The behavior of the device has been analytically modeled through the pseudo-rigid body model methodology and simulated with finite elements models in order to study and optimize its performance. The results coming from the presented models and the device operation have been experimentally validated by characterizing a prototype of this device micro-fabricated in the MetalMUMPs process from MEMSCAP. The maximum displacement of the device is ~16 μm with a maximum actuation voltage of 90 V and the maximum exerted force is ~17 mN.