Patent ID: 7982365

Claim:
An elastic wave device comprising: a piezoelectric substrate; an IDT electrode disposed on an upper side of the piezoelectric substrate; a first dielectric layer made of silicon oxide and disposed on an upper side of the IDT electrode; a second dielectric layer made of silicon nitride or aluminum nitride and disposed on an upper side of the first dielectric layer; and an acoustical layer disposed on an upper side of the second dielectric layer, wherein the second dielectric layer has a film thickness in a range of 0.4λ to 0.7λ, where λ represents a wavelength at an operation center frequency of an elastic wave in the piezoelectric substrate, and wherein the piezoelectric substrate is a Y-cut LiNbO 3 substrate with a cut angle ranging from −10 degrees to +30 degrees in which an elastic wave propagates in an X-axis direction or in a direction having a range of ±5 degrees with respect to the X axis.