ACOUSTIC WAVE GUIDE DEVICE AND METHOD FOR MINIMIZING TRIMMING EFFECTS AND PISTON MODE INSTABILITIES

摘要

PROBLEM TO BE SOLVED: To provide a method of forming a SAW transducer or a SAW resonator on a high coupling substrate while guiding energy in a transducer region by insuring wave-guiding in the transducer region.;SOLUTION: Electrodes form an interdigital transducer on a surface of a piezoelectric substrate, and each have a transversely extending center region and transversely opposing edge regions for guiding an acoustic wave longitudinally through the transducer. A silicon oxide overcoat covers the transducer and a silicon nitride layer covers the silicon oxide overcoat within only the center and edge regions. The thickness of the silicon nitride layer is sufficient for providing a frequency modification to the acoustic wave within the center region and is optimized with a positioning of a titanium strip within each of the opposing edge regions. The titanium strip reduces the acoustic wave velocity within the edge regions such that the velocity in the edge regions is less than the wave velocity within the transducer center region.;COPYRIGHT: (C)2012,JPO&INPIT