Silicon SAW parameters extraction and optimization using finite elements analysis

Saw (Surface Acoustic Wave Devices) are small, rugged, low cost, lightweight, reliable and extremely low power. A saw can be used as wirelessly interrogatable and completely passive device in hostile environments. It is important to use exact saw parameter measurement techniques and simulation methods that are able to model the saw devices accurately. In this paper, a simulation study of Rayleigh wave based on stacked Al/AlN/Si(100) devices was carried out. Evolution curves with respect to acoustic phase velocity, reflectivity and electromechanical coupling efficiency for different aluminum Al electrode patterns and different piezoelectric aluminum nitride AlN layer thickneses were quantified by 2D FEM COMSOL simulations. Simulated acoustic mode shapes are presented. The optimized AlN layers and electrode widths are the ones giving High values of coupling factor, velocities and reflectivity. They are deduced from the obtained dispersion curves.