| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a piezoelectric thin film resonator which is hardly broken, suppresses impedance reduction at an anti-resonant frequency, has a high factor Q factor and suppresses generation of a spurious mode. <P>SOLUTION: The present invention relates to a piezoelectric thin film resonator including a piezoelectric resonant stack 14 comprising a piezoelectric layer 2, an upper electrode 12 and a lower electrode 10, a gap 4 formed thereunder, and a substrate 8 supporting the piezoelectric resonant stack. The piezoelectric resonant stack 14 comprises a vibrating area 20 in which the upper electrode 12 and the lower electrode 10 face each other via the piezoelectric layer 2 and which is positioned in accordance with the gap 4, a supporting area 24 in contact with the substrate 8, and a buffering area 22 which is positioned between the vibrating area 20 and the supporting area 24. Thickness (t) of the piezoelectric layer 2 in the buffering area 22 and thickness T of the piezoelectric layer 2 in the vibrating area 20 fulfills a relation of T/8≤t≤T/2, and a wavelength λ of a standing wave existent in a direction parallel to the substrate 8 and a dimension (x) of the buffering area 20 with respect to a direction of the standing wave fulfills a relation of λ/200≤x≤λ/20. <P>COPYRIGHT: (C)2008,JPO&INPIT |
