Fabrication of filter having FBAR resonators

摘要

A resonator includes a piezoelectric thin-film provided on a main surface of a substrate, a first electrode film provided on a first surface of the piezoelectric thin-film, a second electrode film provided on a second surface of the piezoelectric thin-film, a frequency adjustment film provided on one of the first and second electrode films, the frequency adjustment film comprising a film laminate including a first adjustment film provided on said one of the first and second electrode films, and a second adjustment film provided on the first adjustment film. The first adjustment film is used for Deltaf adjustment, and the second adjustment film is used for correcting frequency deviations generated in the filter manufacturing process. Thus, it is possible to accurately control the center frequency of the filter in which the multiple resonators are connected.