摘要 |
An object of the present invention is to provide a piezoelectric thin film device including a single or a plurality of film bulk acoustic resonators wherein a frequency impedance characteristic is unsusceptible to spuriousness. In a film bulk acoustic resonator, a piezoelectric thin film is supported by a support substrate via an adhesive layer. An upper electrode and a lower electrode each having predetermined pattern are formed on upper and lower surfaces of the piezoelectric thin film. Further, on the upper surface of the piezoelectric thin film, an additional film for adding a mass to an outside of an excitation region is formed as superposed on the upper electrode.
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