| 摘要 |
PROBLEM TO BE SOLVED: To provide a thin-film piezoelectric resonator having such a structure as to have no change in anti-resonance frequency even if a circuit shifts in position due to a change in process, and also to provide a filter circuit equipped with the same. SOLUTION: The thin-film piezoelectric resonator comprises a substrate, cavity 14 which penetrates the substrate, bottom electrode 11 which is so formed on the principal plane of the substrate as to cover the cavity, piezoelectric film 12 formed on top of the bottom electrode 11, and top electrode 13. The top electrode 13 consists of a main body 13a which is so formed on the piezoelectric film as to partially overlap the cavity, a projector 13b which is connected to the main body and is so formed on the piezoelectric film that part of it may not overlap the cavity but overlap the bottom electrode, a pull-out piece 13d formed on the piezoelectric film on the opposite side from the projection of the main body, and a connection 13c which connects the main body and the pull-out piece and is so formed on the piezoelectric film that part of it may not overlap the cavity but overlap the bottom electrode. Since parasitic capacities 15 of the projection and the connection have the same size, there is no substantial change in parasitic capacity due to a positional deviation. COPYRIGHT: (C)2007,JPO&INPIT
|
