| CPC H03H 9/0222 (2013.01) [H03H 3/02 (2013.01); H03H 3/04 (2013.01); H03H 3/08 (2013.01); H03H 3/10 (2013.01); H03H 9/02574 (2013.01); H03H 9/02834 (2013.01); H03H 9/54 (2013.01); H10N 30/01 (2023.02); H10N 30/87 (2023.02); H10N 30/877 (2023.02); H03H 2003/023 (2013.01); H03H 2003/027 (2013.01); Y10T 29/42 (2015.01); Y10T 29/49005 (2015.01); Y10T 29/49155 (2015.01)] | 15 Claims |

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1. An elastic wave device comprising:
a supporting substrate;
a first film stacked on the supporting substrate;
a piezoelectric film stacked on the first film; and
an IDT electrode disposed on a surface of the piezoelectric film; wherein
the supporting substrate includes at least one of silicon, sapphire, silicon carbide, and quartz;
the first film includes at least one of silicon oxide, silicon oxynitride, tantalum oxide, media mainly composed of these materials, and media mainly composed of mixtures of these materials;
the at least one of silicon oxide, silicon oxynitride, tantalum oxide, media mainly composed of these materials, and media mainly composed of mixtures of these materials of the first film is in direct contact with the supporting substrate;
the piezoelectric film includes lithium tantalate or lithium niobate;
a thickness of the piezoelectric film is about 1.5λ or less, and a thickness of the first film is about 2λ or less, where A is a wavelength of an elastic wave determined by an electrode period of the IDT electrode; and
a surface acoustic wave propagates in the piezoelectric film.
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