Patent ID: 7626314

Claim:
A surface acoustic wave device which uses a Rayleigh wave as a surface acoustic wave, comprising: a piezoelectric substrate composed of quartz having Euler angles of (0°±5°, 0° to 140°, and 0°±40°); an IDT electrode located on the piezoelectric substrate and including a plurality of electrode fingers; and a piezoelectric film arranged on the piezoelectric substrate so as to cover the IDT electrode and which is composed of c-axis oriented ZnO, the piezoelectric film having a convex portion provided on a surface thereof corresponding to the thickness of the IDT electrode; wherein the IDT electrode is composed of a metal material primarily including at least one metal selected from the group consisting of Al, Au, Ta, W, Pt, Cu, Ni, and Mo, and when the wavelength of the surface acoustic wave is represented by λ, the primary metal of the IDT electrode, a normalized thickness of the IDT electrode normalized by the wavelength of the surface acoustic wave, and a normalized thickness of the piezoelectric film normalized by the wavelength of the surface acoustic wave are within the ranges of each combination shown in the following Table 1: TABLE 1 Normalized Primary metal of thickness of IDT Normalized ZnO IDT electrode electrode thickness Al 0.02 ≦ h/λ ≦ 0.2 0.03 ≦ h/λ ≦ 0.3 Au 0.005 ≦ h/λ ≦ 0.2 0.03 ≦ h/λ ≦ 0.3 Ta 0.005 ≦ h/λ ≦ 0.2 0.03 ≦ h/λ ≦ 0.3 W 0.005 ≦ h/λ ≦ 0.2 0.03 ≦ h/λ ≦ 0.3 Pt 0.005 ≦ h/λ ≦ 0.2 0.03 ≦ h/λ ≦ 0.3 Cu 0.02 ≦ h/λ ≦ 0.2 0.03 ≦ h/λ ≦ 0.3 Ni 0.02 ≦ h/λ ≦ 0.2 0.03 ≦ h/λ ≦ 0.3 Mo 0.01 ≦ h/λ ≦ 0.2 0.03 ≦ h/λ ≦ 0.3.