摘要 |
The present invention is directed to improving characteristics of a piezoelectric thin film device. A piezoelectric thin film filter including four film bulk acoustic resonators has a configuration where a filter section and a base substrate are bonded to each other via an adhesive layer, the filter section including a piezoelectric thin film which cannot stand up individually under its own weight, the flat base substrate mechanically supporting the filter section. As a piezoelectric material constructing the piezoelectric thin film, it is desirable to use a single-crystal material including no grain boundary, selected from crystal, lithium niobate, lithium tantalite, lithium tetraborate, zinc oxide, potassium niobate, and langasite. |