Analysis of Piezoelectric Aluminium Nitride Thin Film on Silicon Thickness Shear Mode Microelectromechanical Resonators

Abstract

In this project, it analysed the relationship between length and current and the relationship between length and displacement of a piezoelectric microelectromechanical resonator based on silicon with aluminium nitride (AIN) thin film in a thickness shear mode (TSM) so as to design a suitable resonator devoted to micro-biomedical engineering field for mass detection in liquid. Observing the change of resonant frequency of a piezoelectric resonator can predict the mass variation. Traditionally quartz crystal microbalance achieves this application due to direct piezoelectric effect vibrating in TSM naturally but silicon does not have and hence there is a piezoelectric material placed on top of it. Applying the voltage and external stress to resonator causes generation of current due to direct piezoelectric effect. Both 2D and 3D models of resonator are built with a view to investigating the effect of Cm caused by width in 3D and the relationship between length and Cm by means of Butterworth Van Dyke Model of a quartz crystal resonator. It involves finite element modelling of resonator for simulation and calculation by COMSOL. Range of length used for the resonator is from 60 μm to 160 μm in 2D model and from 60 μm to 120 μm in 3D model with a 20 μm gap between consecutive lengths.