Analysis of additional surface mechanical features in micro-acoustic devices - A combined FEM-JTFA approach

In this paper, we propose a hybrid method for the analysis of mechanical features added to the surface of micro-acoustic devices. The proposed technique has been successfully applied to evaluate the influence of additional elastic protective barriers (EPBs) placed on the otherwise planar surface of an 128°YX-LiNbO₃ Surface Acoustic Wave (SAW) device. The developed technique is based on the application of the Finite Element Method (FEM), followed by a problem-adapted Joint Time-Frequency Analysis (JTFA). The combined approach simultaneously considers the micro-acoustic device response in both time and frequency domains, thereby providing a comprehensive understanding of underlying physics. The technique is shown to be more sensitive to higher-order effects such as electromagnetic feedthrough than traditional methods. Furthermore, the proposed technique can be employed to assist in the design of SAW structures where protective barriers can be used to generate constructive interference, enhancing device response.