ELASTIC SURFACE WAVE DEVICE

摘要

A surface acoustic wave device utilizing a Rayleigh wave is provided. The surface acoustic wave device can reduce the generation of ripples and the influence of a spurious component due to an SH wave. Thus, the surface acoustic wave device has excellent frequency characteristics, as well as excellent temperature characteristics. A surface acoustic wave device (1) includes a LiNbO 3 substrate (2) having Euler angles (0° ± 5°, ¸, 0° ± 10°); electrodes that are disposed on the LiNbO 3 substrate (2), are mainly composed of Cu, and include an IDT electrode (3); a first silicon oxide film (6) having the same thickness as the electrodes and disposed in an area other than an area on which the electrodes including the IDT electrode (3) are disposed; and a second silicon oxide film (7) disposed on the electrodes and the first silicon oxide film (6), wherein the Euler angle ¸ and the normalized thickness H of the second silicon oxide film (7) are selected to satisfy the formula (1) or (2). - 50 × H 2 - 3.5 × H + 38.275 ‰ ¸ ‰ 10 �¢ H + 35 wherein H < 0.25 - 50 × H 2 - 3.5 × H + 38.275 ‰ ¸ ‰ 37.5 wherein H ‰¥ 0.25