Elastic wave device including a high acoustic velocity film and a low acoustic velocity film

摘要

An elastic wave device includes a high acoustic velocity film configured such that a bulk wave propagates at a higher acoustic velocity than an elastic wave that propagates in a piezoelectric film, a low acoustic velocity film configured such that a bulk wave propagates at a lower acoustic velocity than a bulk wave that propagates in the piezoelectric film is laminated on the high acoustic velocity film, the piezoelectric film is laminated on the low acoustic velocity film, and an IDT electrode is laminated on one surface of the piezoelectric film. In an upper structure section, an energy concentration ratio of a main mode which is an elastic wave is not less than about 99.9% and an energy concentration ratio of a high order mode which is spurious is not more than about 99.5%.