4E-6 Thermal Effect of Surface Acoustic Waves in Quartz Substrates Covered by a Metal Layer

Thermal property of surface acoustic wave (SAW) resonators is always of interests to product design and applications with the objective of accurate prediction of device performance. Theoretical and experimental studies have been carried out for the prediction of the thermal effect of piezoelectric substrates undergoing temperature change and structural complications frequently encountered in acoustic wave resonators like the presence of metal electrodes. The analysis is usually done with experimental data for the frequency-temperature relation with improved analytical models for the consideration of electrodes. In this study, we employee the incremental thermal field theory and accompanying material constants for quartz crystals, which were intended for the bulk acoustic wave (BAW) resonators analysis, to the analysis of an ideal model of SAW resonators. By taking into account the material constant dependence on temperature through the cubic relation and thermal effects on strains and equations of motion, SAW propagating in quartz crystals is formulated with the incremental thermal field theory. Our calculation of the velocity-temperature relation of quartz crystal substrates is an improvement of earlier predictions.