摘要:
A thin film bulk acoustic resonator (FBAR) includes a first electrode, a first piezoelectric layer having a first c-axis orientation and on the first electrode, a second piezoelectric layer having a second c-axis orientation over the first piezoelectric layer, and a second electrode on the second piezoelectric layer. The first and second piezoelectric layers are made of respective different piezoelectric materials. The FBAR can be set to have different resonance frequencies by selecting the first and second c-axis orientations to be respectively the same or different. The high and low frequency range of the FBAR can thus be extended.