Quantitative Analysis of Power Leakage in an Film Bulk Acoustic Resonator Device at the Antiresonance Frequency

Abstract

In this paper we analyze for the first time quantitatively the acoustic losses in a film bulk acoustic wave resonator (FBAR), which are expected to deteriorate the device performance. To this end, we regard the effective acoustic admittance, conduct laser probing measurements and finite element modeling (FEM). For our device under test (DUT) at the anti-resonance frequency, we compare the relative power of observable modes in the active and passive area and point out the relevant energy loss mechanism in terms of a single mode. By scattering analysis of the resonator's border region, we can identify the respective excitation mechanism within the active area and therefore can consider specific countermeasures to improve the device performance. Practically applied for the first time, the utilized methods and the overall procedure are explained in detail and are applicable to investigate acoustic energy loss as well at other frequencies as in other devices.