| 摘要 |
In the boundary acoustic wave device, an IDT electrode, a first dielectric layer, and a second dielectric layer are provided on a piezoelectric substrate. The first dielectric layer is made of a deposited film. A thickness of the IDT electrode is about 10% or more of lambda. A difference between a height of the first dielectric layer, measured from an upper surface of the piezoelectric substrate, above a center of an electrode finger of the IDT electrode and a height of the first dielectric layer, measured from the upper surface of the piezoelectric substrate, above a center of a gap between adjacent electrode fingers, i.e., a magnitude of unevenness in an upper surface of the first dielectric layer, is about 5% or less of lambda.
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