AlN on polysilicon piezoelectric cantilevers for sensors/actuators

In this work, we report on the fabrication and characterization of aluminium nitride (AlN)-based piezoelectric cantilevers to be applied both as pressure/force or inertial sensors and as microactuators. The fabricated structures exploiting a piezoelectric AlN thin film embedded between two molybdenum (Mo) electrodes are deposited by DC magnetron sputtering on a polysilicon (PolySi) thin elastic layer. Cantilever arrays of different lengths consisting of PolySi/Mo/AlN/Mo layers are realized by using conventional micromachining techniques involving optical lithography and etching processes. The fabrication of the piezoelectric cantilevers is reported and a first resonance frequency of 30.2 kHz has been measured by LCR electrical measurements. The operation of the cantilever as microactuator has been investigated by atomic force microscopy (AFM) around the first resonance frequency showing a vertical displacement of more than 16 nm by the application of only 0.1 V.