Novel Bulk acoustic wave resonator structure for reducing electrical loss of electrodes

A Bulk acoustic wave (BAW) resonator is an essential component in the RF filter and duplexer of mobile devices. The BAW resonator consists of a piezoelectric layer sandwiched between a top electrode and a bottom electrode. In this paper, a novel BAW resonator structure is presented to reduce the electrical loss of electrodes and thereby lower insertion loss which is important to achieve low loss RF filter and duplexer. For that, the resonator is designed to have a gold band of 12 um wide and 2 um high on its perimeter in which half region is connected to the top electrode and the other half the bottom electrode near the perimeter, respectively. As results, insertion loss of the resonator is reduced from -0.05dB to -0.03dB at resonance frequency. Q-factor and electrode resistance are also improved from 995 to 1360 and 1.07Ω to 0.81Ω, respectively.