Surface acoustic wave device

摘要

A surface acoustic wave device has a high electromechanical coefficient and reflection coefficient, and also has an improved frequency-temperature characteristic that is achieved by forming a SiO₂ film on an IDT so as to prevent cracking from occurring on a surface of the SiO₂ film so that desired properties can be reliably obtained. The surface acoustic wave device includes at least one IDT, which is composed of a metal or an alloy having a density higher than that of Al and is formed on a 25° to 55° rotation-Y plate X propagation LiTaO₃ substrate, and a SiO₂ film disposed on the LiTaO₃ substrate so as to cover the at least one IDT for improving the frequency-temperature characteristic.