Influence of Etching Trench on Keff2 of Film Bulk Acoustic Resonator

Micromachines

Jie Zhou¹  Yan Liu¹  Yang Zou¹  Chengliang Sun¹  Wenjuan Liu¹  Yao Cai¹  Chao Gao¹ 

[1] The Institute of Technological Sciences, Wuhan University, Wuhan 430072, China;

关键词: radio frequency (RF);    MEMS;    FBAR;    effective electromechanical coupling coefficient;   

DOI  :  10.3390/mi13010102

来源: DOAJ

【 摘 要 】

As radio-frequency (RF) communication becomes more ubiquitous globally, film bulk acoustic resonators (FBAR) have attracted great attention for their superior performance. One of the key parameters of an FBAR, the effective electromechanical coupling coefficient ($K_{eff}^2$), has a great influence on the bandwidth of RF filters. In this work, we propose a feasible method to tune the $K_{eff}^2$ of the FBAR by etching the piezoelectric material to form a trench around the active area of the FBAR. The influence of the position of the etching trench on the $K_{eff}^2$ of the FBAR was investigated by 3D finite element modeling and experimental fabricating. Meanwhile, a theoretical electrical model was presented to test and verify the simulated and measured results. The $K_{eff}^2$ of the FBAR tended to be reduced when the distance between the edge of the top electrode and the edge of the trench was increased, but the Q value of the FBAR was not degraded. This work provides a new possibility for tuning the $K_{eff}^2$ of resonators to meet the requirements of different filter bandwidths.

【 授权许可】

Unknown