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.

Elastic constant of dielectric nano-thin films using three-layer resonance studied by picosecond ultrasonics

“…Elastic constants and sound velocities of thin films are essential parameters of surface acoustic wave (SAW) filters, [1][2][3][4] film bulk acoustic resonators (FBAR), [5][6][7] and acoustic mirrors 8,9) for wireless communication. Next-generation communication uses much higher frequency band-pass filters, 10,11) which are composed of much thinner films.…”

Bulk acoustic wave resonator with suppressed energy loss using improved lateral structure

“…As BAW resonator shows low vertical acoustic leakage due to air-gap structure or alternating acoustic mirror stacks implemented underneath the resonator, it performs lower losses and higher Q-factors than surface acoustic wave (SAW) resonators. Although BAW resonators utilize longitudinal acoustic waves, lateral acoustic waves are also generated in a large amount especially during anti-resonance [4,5,6,7]. Suppression of this lateral acoustic wave leakage is important for its antiresonance performances such as Q a and kt 2 .…”

Suppression of Brillouin oscillation in transparent free-standing diamond thin films in picosecond ultrasound

“…This technique is highly promising for evaluating ultrasound attenuation in thin films, [5][6][7][8] which is an important parameter for designing ultrahigh-frequency ultrasonic-resonator devices such as bulk-acoustic-wave resonators. [9][10][11] The most reliable attenuation measurement can be made on a freestanding thin film because of no energy leakage to the substrate. The free-standing thin film is also suitable for sensor applications, including mass-sensitive biosensors.…”