Chen Yoshimura LLP
Piezoelectric thin film resonator, filter, and duplexer
A piezoelectric thin film resonator includes: a piezoelectric film located on a substrate, and formed of stacked lower and upper piezoelectric films; lower and upper electrodes facing each other across at least a part of the piezoelectric film; and an insertion film inserted between the lower and upper piezoelectric films, wherein an air gap including a resonance region where the lower and upper electrodes face each other across the piezoelectric film and being larger than the resonance region is located under the lower electrode, and a multilayered film formed of the lower piezoelectric film, the insertion film, and the upper piezoelectric film is located in at least a part of a region located further out than an outer outline of the resonance region, further in than an outer outline of the air gap, and surrounding the resonance region, and is not located in a center region of the resonance region.
TAIYO YUDEN CO., LTD.
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Tsuyoshi Jiansong
Yokoyama Liu