Patent ID: 9621128
Date: 2017-04-11
CPC Classifications: H01L,H03H

Claim:
1. An elastic wave device including a piezoelectric film, the elastic wave device comprising: a support substrate; a high acoustic velocity film located on the support substrate and configured such that a bulk wave propagates at a higher acoustic velocity than an elastic wave that propagates in the piezoelectric film; a low acoustic velocity film located on the high acoustic velocity film and configured such that a bulk wave propagates at a lower acoustic velocity than a bulk wave that propagates in the piezoelectric film; the piezoelectric film located on the low acoustic velocity film; and an IDT electrode located on one surface of the piezoelectric film; wherein an acoustic velocity of a main mode which is an elastic wave in use at an anti-resonant frequency is V1 [m/s], an acoustic velocity in the high acoustic velocity film is Vh [m/s], a film thickness of the high acoustic velocity film normalized with a wavelength λ [m] of the elastic wave is Th, and V1 and Th satisfy for each value of Vh relationships including: when 4200≦Vh<4400: when 4400≦Vh<4600: when 4600≦Vh<4800: when 4800≦Vh<5000: when 5000≦Vh<5200: when 5200≦Vh<5400: when 5400≦Vh<5600: when 5600≦Vh<5800: when 5800≦Vh<6000: when 6000≦Vh: