Patent ID: 7705515

Claim:
A surface acoustic wave device utilizing a Rayleigh wave comprising: a LiNbO 3 substrate having Euler angles of (0°±5°, θ±5°, 0°±10°); an electrode disposed on the LiNbO 3 substrate and including an IDT electrode primarily including Cu; a first silicon oxide film disposed in a region other than a region in which the electrode is disposed, the first silicon oxide film having a film thickness substantially equal to the thickness of the electrode; and a second silicon oxide film arranged to cover the electrode and the first silicon oxide film; wherein the film thickness of the electrode is in a range of 0.12λ to 0.18λ, where λ represents the wavelength of a surface acoustic wave, and θ of the Euler angles of (0°±5°, θ±5°, 0°±10°) is specified to be within a range satisfying the following Formula (1): θ=32.01−351.92×exp(− T Cu /0.0187) Formula (1) where T Cu is a value of the Cu electrode film thickness normalized with the wavelength λ.