We demonstrate compact analytical multi-physics models that accurately predict the deformed shape of a variety of multilayer cantilevers and the associated electrical characteristics when employed in several practical sensor and RF applications. We pay particular attention to structures relying on large mechanical displacements in order to achieve the desired performance. Practical applications of these cantilevers are shown in several important cases including; (a) a harsh-environment temperature sensor; (b) high-Q three-dimensional inductors; (c) an electrothermal actuator for highly tunable inductor; and (d) mm-wave on-chip antenna with high radiation efficiency. In all cases, obtaining large deflections is key in achieving the required performance.

For example, the capacitance variation of the developed temperature-sensitive capacitor (first application) depends on the distance between its upper and lower electrodes. For the 85 micron tip deflection of bimorph capacitor, about 2.5:1 ca-pacitance variation from room temperature to 213 degrees C is experimentally obtained. Electro-thermo-mechanical model is proposed to predict capacitance in terms of temperature. Besides the temperature sensors, a pre-stressed metal 3-D inductor is analyzed (second application). Contrary to conventional inductor models, the developed models include both mechanical and electrical components. Starting from basic process parameters such as residual stress of the cantilevers beams the model provides the self-assembled inductor characteristics.

A tunable MEMS inductor with electrothermal actuators is the third application investigated. This inductor is based on an integrated transformer architecture with one inductor is shorted. Tunability is accomplished by varying the magnetic coupling coefficient which is dominated by the distance between the two inductors. Design rules for optimized performance are provided. The fabricated tunable inductor shows about 2:1 inductance variation. Finally, mm-wave on-chip antennas with high radiation efficiency are presented. The residual stresses in thin films result in out-of-plane structures over a ground plane that isolates the radiating elements from the high-loss substrate. Consequently, these antennas achieve high radiation efficiency of more than 60 percent.