SAW device analysis using a combination of FEM/BEM calculations and scanning interferometer measurements

Scanning laser interferometry has proven useful in the identification of novel acoustic loss phenomena. However, it remains challenging to provide a rigorous physical interpretation of the details of the optically measured acoustic field distribution. With the help of our powerful FEM/BEM finite transducer model, we can make a direct comparison between the measured and simulated acoustic field distributions. This enables us to search and correct for unwanted acoustic phenomena which can deteriorate the filter performance. Here we focus on the modeling of the stress at the interface between the electrodes and the substrate. We describe the FEM/BEM tool for finite transducers that we have developed and its validation with optical Michelson interferometer scans. We show how it is possible to evaluate and optimize the power-handling properties of a SAW device structure.