FBAR有效机电耦合系数的影响因素分析  

Analysis of Influence Factors of FBAR Effective Electromechanical Coupling Coefficient

作　　者：赵坤丽 高杨[3,4] 韩超[1] 

机构地区：[1]西南科技大学信息工程学院,四川绵阳621010 [2]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,北京100049 [3]中国工程物理研究院电子工程研究所,四川绵阳621999 [4]重庆大学新型微纳器件与系统技术国防重点学科实验室,重庆400044

出　　处：《压电与声光》2017年第2期202-206,共5页Piezoelectrics & Acoustooptics

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)

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。For two species influence factors of the effective electromechanical coupling coefficient（k（eff）~2）,i.e.,the electrode/piezoelectric layer thickness ratio of FBAR and c-axis orientation of piezoelectric layer,a simulation model of three-layers composites FBAR was established focusing on the variable thickness ratio and variable degree of c-axis orientation in this paper.By using a FBAR with a resonant frequency of 2.185 GHz as a case study,it′s simulation results showed that the k（eff）~2 declined slightly when thickness ratio was 0.206,but the thickness of Mo electrodes was 0.247μm and AlN piezoelectric layer was 1.119 7μm,which resulted in good electrical properties of FBAR and reduced the process complexity and fabrication time.On the other hand,when the c-axis inclination angle was 3°,it would reduce the k（eff）2 of FBAR.A the same time,the impedance characteristics curve of FBAR would present a strong sense of spurious resonance,causing the lateral energy leakage in FBAR and deteriorating the insertion loss of FBAR filters.So the key process parameters should be strictly adjusted to fabricate the high quality AlN thin film.In addition,the appropriate relaxation of the resonant frequency increment of FBAR would enable the k（eff）~2 to have a certain redundancy,which could compensate the k（eff）~2 reduction resulted by the preparation process.

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 

分 类 号：TN713[电子电信—电路与系统] TN603