SURFACE ACOUSTIC WAVE FILTER AND PREPARATION METHOD THEREFOR, RADIO-FREQUENCY FRONT-END CHIP, AND MOBILE TERMINAL

摘要

A surface acoustic wave filter and a preparation method therefor. The filter comprises a substrate (10) and a piezoelectric material layer (20) arranged opposite each other, wherein a cavity (30) is provided between the substrate (10) and the piezoelectric material layer (20); an interdigital transducer (202) is provided on the surface of the piezoelectric material layer (20) facing the substrate (10); and the interdigital transducer (202) is located inside the cavity (30). The interior of the cavity (30) may be a vacuum environment, and may also be a gaseous environment. An acoustic wave cannot be propagated in a vacuum, and the propagation capability of the acoustic wave in a gaseous medium is lower than that in a solid medium, such that acoustic wave energy does not easily leak out from the substrate (10) via the cavity (30). Therefore, by means of the cavity (30) formed between the substrate (10) and the piezoelectric material layer (20), the occurrence of acoustic waves in a stray mode can be reduced, such that the possibility of the acoustic energy leaking from the substrate (10) is reduced, thereby increasing a Q value and the insertion loss of the SAW filter. In addition, further disclosed are a radio-frequency front-end chip including the surface acoustic wave filter, and a mobile terminal.