Patent ID: 7902718

Claim:
A boundary acoustic wave device comprising: a LiNbO 3 substrate including a plurality of grooves provided in an upper surface thereof and having Euler angles (0°, θ, −45° to +45°); electrodes defined by metal material filled in the grooves; and a silicon dioxide layer arranged over the LiNbO 3 substrate and the electrodes; wherein the upper surface of the silicon dioxide layer is flat or substantially flat; the metal material defining the electrodes is Au; and a thickness of the electrodes made of Au, θ of the Euler angles of the LiNbO 3 substrate, and the thickness of the silicon dioxide layer are within any of the ranges shown in the table below: α ≦ 0.1 θ of Euler angles (0°, θ, −45° to 45°) 0.01 ≦ Thickness of (0, 61 to 112, −45 to 45) 0.8 ≦ Thickness of Au electrode < 0.02 silicon dioxide layer ≦ 4.0 0.02 ≦ Thickness of (0, 60 to 122, −45 to 45) 0.8 ≦ Thickness of Au electrode < 0.06 silicon dioxide layer ≦ 4.0 0.06 ≦ Thickness of (0, 56 to 132, −45 to 45) 0.8 ≦ Thickness of Au electrode < 0.08 silicon dioxide layer ≦ 4.0 0.08 ≦ Thickness of (0, 51 to 136, −45 to 45) 0.8 ≦ Thickness of Au electrode ≦ 0.10 silicon dioxide layer ≦ 4.0 The thickness of each electrode and the thickness of a silicon dioxide layer are normalized thickness H/λ (λ is the wavelength of a boundary acoustic wave).