| 摘要 |
PROBLEM TO BE SOLVED: To enhance characteristics of a piezoelectric thin film device including a piezoelectric thin film resonator by suppressing the sub-resonance of the piezoelectric thin film resonator. SOLUTION: In the piezoelectric thin film device, a piezoelectric thin film resonator 1 has such a structure as an adhesive layer 12, a cavity forming film 13, a lower surface electrode 14, a piezoelectric thin film 15 and upper surface electrodes 16(161, 162) are laminated in this order on a supporting substrate 11. After the piezoelectric thin film 15 is secured to the supporting substrate 11 at the outside of the opposite region 181 and a cavity 135 is made larger than a drive portion 1611, a weighting part 1615 is arranged at the periphery of the drive portion 1611 and a reduction part 1616 is arranged closer to the central portion than the weighting part 1615. Consequently, sub-resonance superimposed between the resonance frequency and the anti-resonance frequency of main resonance or sub-resonance superimposed to the side of a lower frequency than the resonance frequency of main resonance can be suppressed to such a level as causing no practical problem and the Q value of main resonance can be increased sharply. COPYRIGHT: (C)2008,JPO&INPIT
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