A bilayer structure laterally excited bulk acoustic resonator with enhanced heat dissipation and acoustic properties

The poor heat dissipation of the laterally excited bulk acoustic resonator (XBAR) based on a single-layer piezoelectric film prevents it from sustaining operation under high-power conditions. Consequently, it is critical to improve the heat dissipation and enhance the power handling capability of the device. To address the limitation of poor heat dissipation, this study proposes a bilayer XBAR consisting of a piezoelectric layer and a thermally conductive layer (Si, SiC, or diamond), which possesses excellent acoustic properties and heat dissipation performance. The finite element simulation results indicate that the bilayer XBAR has higher operating frequencies and excellent electromechanical coupling coefficients. The bilayer structures feature lower thermal resistance and more uniform heat distribution. A maximum device temperature rise of only 2.8 °C was obtained with a diamond thermally conductive layer at an input power of 26 dBm and the temperature reduction efficiency reached 85%. More importantly, the maximum temperature rise is only 19.3 °C at an input power of 30 dBm. The approach of using the bilayer structure provides a solution for designing XBARs with high-power handling capability.