A Way to Increase Q of FBARs Using Supporting Column

This paper presents a thin film bulk acoustic resonator (FBAR) with a supporting column structure. The supporting column structure is placed at the vertex of each side of the resonator. The area around the active area of the resonator can be etched to form a trench structure. This structure can reduce the transmission of the lateral acoustic wave to the inactive area and increase the quality factor (Q-factor) of the resonator. Different dimensions of the square supporting column structure are compared in this paper and results show that as the width of the square supporting column increases, the Q-factor of the resonator increases accordingly. Because of the influence of the coupling capacitance at the supporting column, the effective coupling coefficient
$(\boldsymbol{K}_{eff}^{2})$
of the resonator gradually decreases as the width of the supporting column increases.