FBAR有效机电耦合系数的影响因素分析

发布时间：2018-02-04 18:15

本文关键词： 薄膜体声波谐振器(FBAR) 有效机电耦合系数厚度比 c轴取向寄生谐振横向能量泄漏　出处：《压电与声光》2017年02期 　论文类型：期刊论文

【摘要】：针对有效机电耦合系数(k2eff)的两种影响因素-薄膜体声波谐振器(FBAR)的电极/压电层厚度比与压电层薄膜的c轴取向,分别建立了厚度比可变与c轴取向可变的三层复合结构的FBAR三维仿真模型。以一个谐振频率为2.185GHz的FBAR谐振器作为分析案例,通过仿真得出,设计得到的膜层厚度比为0.206时,虽然FBAR的k2eff略有下降,但此时Mo电极厚为0.247μm,AlN压电层厚为1.119 7μm,使得FBAR电学性能较好,工艺制备复杂度及时间降低。另外,c轴倾斜角度为3°时,会使FBAR的k2eff下降,同时FBAR阻抗特性曲线产生较强的寄生谐振,这会引起FBAR横向能量泄露,恶化FBAR滤波器的带内插损。因此,在制备AlN薄膜时应该严格把握各项工艺参数。此外,通过适当放宽FBAR谐振器谐振频率增量能使k2eff具有一定冗余量来弥补工艺制备引起的k2eff下降。
[Abstract]:The electrode / piezoelectric layer thickness ratio of the thin film bulk acoustic resonator FBARs and the c-axis orientation of the piezoelectric layer film are studied in view of the two influencing factors of the effective electromechanical coupling coefficient k2eff. A three-layer FBAR simulation model with variable thickness ratio and variable c-axis orientation is established respectively. A FBAR resonator with a resonant frequency of 2.185GHz is used as an analysis case. The simulation results show that the thickness ratio of the film is 0.206, and the thickness of Mo electrode is 0.247 渭 m, although the K2eff of FBAR decreases slightly. The piezoelectric layer thickness of AlN is 1.119 7 渭 m, which makes the electrical properties of FBAR better, and the preparation complexity and time are reduced. In addition, when the tilt angle of C axis is 3 掳, the piezoelectric layer thickness is 1.119 7 渭 m. K2eff of FBAR will decrease, and the characteristic curve of FBAR impedance will produce strong parasitic resonance, which will cause the lateral energy leakage of FBAR and worsen the band interpolation loss of FBAR filter. In the preparation of AlN thin films, we should strictly grasp the process parameters. By loosening the resonant frequency increment of FBAR resonator properly, the k _ 2eff has some redundancy to compensate for the decrease of k _ 2eff caused by the process preparation.
【作者单位】：西南科技大学信息工程学院;中国科学院高能物理研究所核探测与核电子学国家重点实验室;中国工程物理研究院电子工程研究所;重庆大学新型微纳器件与系统技术国防重点学科实验室;
【基金】：国家自然科学基金资助项目(61574131) 中国工程物理研究院超精密加工技术重点实验室基金资助项目(2014ZA001) 核探测与核电子学国家重点实验室开放课题基金资助项目(2016KF-02) 西南科技大学特殊环境机器人技术四川省重点实验室开放基金资助项目(14ZXTK01)
【分类号】：TN65
【正文快照】： 0 引言有效机电耦合系数(k2eff)是评价薄膜体声波谐振器(FBAR)声学性能的一个重要指标。k2eff决定FBAR串、并联谐振点间的频率增量[1],进而决定了FBAR滤波器的带宽,过低的k2eff会限制FBAR在宽带滤波器中的应用[2]。其次,针对某一设计指标,如果实测出来的k2eff低于设计值会导

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