Surface acoustic wave device

Abstract

A surface acoustic wave device includes a Y-cut, X-propagation LiTaO3 substrate, at least one interdigital transducer provided on the LiTaO3 substrate and made of Al or a metal containing Al as a major component, and an SiO2 film provided on the surface of the LiTaO3 substrate so as to cover the interdigital transducer, wherein the thickness Hs of the SiO2 film normalized by the wavelength λ of a surface acoustic wave and the cut angle θ of the LiTaO3 substrate are set to be in any one of the ranges represented by formulae (1) to (8): in the case of 0.00 <Hs≦0.05, 30°<θ<36°  (1) in the case of 0.05<Hs≦0.10, 29°<θ<36°  (2) in the case of 0.10<Hs≦0.15, 28°<θ<36°  (3) in the case of 0.15<Hs≦0.20, 27°<θ<36°  (4) in the case of 0.20<Hs≦0.25, 26°<θ<36°  (5) in the case of 0.25<Hs≦0.30, 25°<θ<35°  (6) in the case of 0.30<Hs≦0.35, 23°<θ<34°  (7) in the case of 0.35<Hs≦0.40, 21°<θ<31°  (8).

Dependencies are inferred from the claim text.