# Enhancement of Quality Factors in a 6.5 GHz Resonator Using Mo/SiC Composite Microstructures

## TL;DR

This paper introduces a new Mo/SiC composite structure that improves the performance of high-frequency resonators by reducing acoustic wave leakage.

## Contribution

A novel Mo/SiC composite microstructure is proposed to enhance acoustic confinement in FBARs through multiple reflection boundaries.

## Key findings

- SiC microstructures suppress vibration amplitudes in non-resonant regions.
- The Mo/SiC composite structure increases the quality factor (Q) by 51.2% compared to basic FBARs.
- The fabricated resonator achieves a 6.488 GHz resonance frequency and a Q of 310.

## Abstract

This study addresses the critical challenge of lateral acoustic wave energy leakage in high-frequency film bulk acoustic resonators (FBARs) and elucidates the reflection mechanism of acoustic waves at acoustic reflection boundaries. Based on the theory of acoustic impedance mismatch, a novel Mo/SiC composite microstructure is designed to strategically establish multiple acoustic reflection boundaries along the lateral acoustic wave leakage paths. Finite element simulations reveal that SiC microstructures effectively suppress vibration amplitudes in non-resonant regions, thereby preventing acoustic wave leakage. By integrating Mo and SiC microstructures, the proposed composite structure significantly enhances the resonator’s acoustic confinement and energy retention capabilities. A resonator incorporating this Mo/SiC composite microstructure is fabricated, achieving a series resonance frequency of 6.488 GHz and a remarkable quality factor (Q) of 310. This represents a substantial 51.2% improvement in Q compared to the basic FBAR, confirming the effectiveness of the proposed design in mitigating lateral acoustic wave leakage and enhancing resonator performance for high-frequency, low-loss applications. This work offers valuable insights into the design of next-generation RF resonators for advanced wireless communication systems.