PIEZOELECTRIC THIN FILM RESONATOR, FILTER, COMMUNICATION MODULE, COMMUNICATION DEVICE

摘要

PROBLEM TO BE SOLVED: To suppress lateral direction leakage at a piezoelectric thin film resonator to raise a Q value.

SOLUTION: An end 2a of an upper electrode 2 is made into the shape of eaves projected from an end 4a of a piezoelectric film 4. The end 2a is made into an inverse tapered shape. A lower end 2b of the end 2a is arranged to be matched with or close to the end 4a of the piezoelectric film 4. According to the arrangement, elastic waves propagating inside of the piezoelectric film 4 can be shut up. Thereby, the Q value can be raised while loss can be reduced.

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