PIEZOELECTRIC THIN FILM RESONATOR AND FILTER

摘要

PROBLEM TO BE SOLVED: To provide a piezoelectric thin film resonator and a filter whose variances in resonance characteristics and filter characteristics are small, and reliability is high.

SOLUTION: The piezoelectric thin film resonator and filter are equipped with a lower electrode (12) formed on a substrate (10), a piezoelectric thin film (14) formed on the lower electrode (12), and an upper electrode (16) formed on the piezoelectric film (14). A membrane region (22) where the upper electrode (12) and the lower electrode (16) overlap interposing the piezoelectric film (14) between is elliptical, and the lower electrode (12) extends outside the membrane region in regions other than the lead out electrode portion (16b) of the upper electrode (16) and the lead out electrode (12b) of the lower electrode (12).

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