SiO_(2)/W反射叠层的分布电容对体波谐振器的影响  

Influence of Distributed Capacitance of SiO_(2)/W Reflection Stack Layer to Bulk Acoustic Wave Resonator

作　　者：吴兆辉 唐盘良[1,2] 李桦林[2] 米佳 鲍景富[1] WU Zhaohui;TANG Panliang;LI Hualin;MI Jia;BAO Jingfu(University of Electronic Science and Technology of China,School of Integrated Circuit Science and Engineering,Chengdu 611731,China;The 26th Institute of China Electronics Technology Group Corporation,Chongqing 400060,China)

机构地区：[1]电子科技大学集成电路科学与工程学院,四川成都611731 [2]中国电子科技集团公司第二十六研究所,重庆400060

出　　处：《压电与声光》2023年第3期346-349,354,共5页Piezoelectrics & Acoustooptics

基　　金：国家自然科学基金资助项目(U1430102);科技部科技支撑计划基金资助项目(GG22012412C)。

摘　　要：该文使用SiO_(2)和金属材料钨(W)构造布喇格反射叠层,将其应用于由横向电场激励体声波谐振器(XBAR),并分析了金属层对谐振器性能的影响。所设计的谐振器以128°YX-切铌酸锂为压电层,Al为电极,SiO_(2)和W为周期层叠结构,单晶硅作为衬底的固态装配型谐振器(SMR),利用叉指电极换能器(IDT)激发出A1模式。首先计算声阻抗层厚度对SiO_(2)/W叠层传输系数的影响,得到中心频率为3.7 GHz的布喇格阻带。横波(主模)在经过叠层时被反射,纵波(杂模)则部分地泄露到衬底。由于钨具有电导性,致使IDT与钨之间形成并联分布电容,改变了原有的电场分布,导致谐振器的耦合系数下降。通过实验测试谐振器的实际性能,获得耦合系数为12%。虽然W具有高声阻抗,但分布电容的影响恶化了电气参数。In this paper,a Bragg reflective layer is constructed by suing silicon dioxide(SiO_(2))and tungsten(W),which is used to the laterally excited bulk acoustic wave resonator(XBAR).The influence of metal layer on the performance of the resonator is investigated.The designed resonator is a solidly mounted resonator(SMR)consisting of piezoelectric layer of 128°YX cut lithium niobate,aluminum electrode,SiO_(2) and W as the periodical stack layer structure,silicon as the substrate,while A1 mode is excited by interdigital transducer(IDT).First,the influence of thickness of stack layers to the transmittance of SiO_(2)/W stack layer is investigated,and the center frequency of Bragg stop band is set at 3.7 GHz.It is found that the transverse wave(main mode)is reflected as it passes through the stack layer,while the longitudinal wave(stray wave)is partially leaked into the substrate.However,due to the conductivity of tungsten,the parallel distributed capacitor is formed between IDT and tungsten layer,which changes the original electric field distribution and leads to a decrease in the coupling coefficient of the resonator.The actual performance of the resonator is tested experimentally a coupling coefficient of 12%is obtained.Although tungsten possesses high acoustic impedance,the distributed capacitance degrades the electric parameters of the resonator.

关 键 词：SiO_(2)/W叠层反射器 铌酸锂 A1模式谐振器 传输系数 

分 类 号：TN384[电子电信—物理电子学] TN75