Patent ID: 8723396

Claim:
A surface acoustic wave device comprising: a quartz crystal substrate having Euler angles (−1.5°≦φ≦1.5°, 117°≦θ≦142°, ψ); and an IDT which has a plurality of electrode fingers on the principal surface of the quartz crystal substrate and excites a surface acoustic wave in a stopband upper end mode, wherein inter-electrode-finger grooves are recessed in the surface of the quartz crystal substrate between adjacent electrode fingers of the IDT, the wavelength λ of the surface acoustic wave and the depth G of the inter-electrode-finger grooves satisfy the relationship 0.01λ≦G, an IDT line occupancy η and the depth G of the inter-electrode-finger groove satisfy the following relationships: −2.0000 ×G/λ+ 0.7200≦η≦−2.5000 ×G/λ+ 0.7775 where 0.0100 λ≦G≦ 0.0500λ; −3.5898 ×G/λ+ 0.7995≦η≦−2.5000 ×G/λ+ 0.7775 where 0.0500 λ≦G≦ 0.0695λ; the Euler angle ψ satisfies |ψ|≠90°×n (where n=0, 1, 2, 3), and the thickness H of the electrode fingers is within a range of 0.05 μm≦H≦0.20 μm.