Temperature-compensated film bulk acoustic resonator above 2 GHz

Two different types of temperature-compensated film bulk acoustic resonators (FBARs) are designed, fabricated, and tested. One is formed by integrating FBAR with a surface-micromachined air-gap capacitor, which passively reduces the FBAR's temperature coefficient of frequency (TCF) by about 40 ppm//spl deg/C at 2.8 GHz. With this approach, zero TCF would easily have been achieved if the FBARs were built on AlN rather than ZnO. The other type of temperature compensated FBAR is built on a surface-micromachined SiO/sub 2/ cantilever that is released by XeF/sub 2/ vapor etching of silicon. The Al-ZnO-Al-SiO/sub 2/ FBAR is measured to have a TCF of -0.45 ppm//spl deg/C (between 85/spl deg/C and 110/spl deg/C) at 4.4 GHz.     

薄膜体声波谐振器有限元仿真与设计

为了抑制薄膜体声波谐振器的寄生谐振,建立了薄膜体声波谐振器的二、三维有限元模型。通过频率响应仿真,分析了不同电极结构的谐振器在中心频率处的振动位移分布情况和频率响应曲线,评估了不同电极结构对谐振器寄生振动的影响,并完成谐振器电极结构的优化设计,实现了谐振器寄生振动抑制。根据仿真优化结果表明,设计并制作了工作频率在1.873GHz的薄膜体声波谐振器,谐振器插入损耗0.7dB,无明显寄生谐振,对设计进行了验证。     

掺镁ZnO基薄膜体声波谐振器的制备和性能研究

固体装配型薄膜体声波谐振器(FBAR)机械强度好,尺寸小,可在硅片上三维立体集成,灵敏度大,在未来的通信设备制作高带通滤波器和物联网传感器中展现出广泛的应用前景。通过射频磁控溅射系统制备了以掺镁ZnO(MgxZn1-xO)作为压电层的固体装配型薄膜体声波谐振器,研究了掺镁ZnO对薄膜体声波谐振器谐振性能的影响。利用场发射扫描电镜(FESEM)对FBAR的结构进行了微观表征。比较了不同掺镁ZnO靶材对于晶向和谐振性能的影响。通过优化条件,制备出了性能优越的FBAR,其谐振频率在1.8~2.4GHz,品质因数(Q)可达800,回波损耗可达-30dB。     

In-Liquid Quality Factor Improvement for Film Bulk Acoustic Resonators by Integration of Microfluidic Channels

We demonstrate a significant improvement in the quality factor $(Q)$ of film bulk acoustic resonators (FBARs) in liquid environments via the integration of microfluidic channels. Our device consists of a longitudinal-mode excited zinc oxide (ZnO) FBAR and parylene-encapsulated microfluidic channels. Considerable enhancement in the $Q$ of the resonant system is obtained by confining the liquid in the microfluidic channels of thickness comparable to the acoustic wavelength. The improved FBAR achieves $Q$ values of up to 120, which represents an improvement of a factor of eight over those of current state-of-the-art devices.      

基于薄膜体声波谐振器的高灵敏度质量传感器

提出了一种针对于生物传感应用的薄膜体声波谐振(Thin film bulk acoustic resonator,FBAR)质量传感器。薄膜体声波谐振器谐振频率非常高(GHz数量级),同时具有很高的品质因数,因此基于这种器件的质量传感器具有非常高的质量灵敏度。提出了三对全金属Al-W层作为布拉格声学反射层的FBAR,采用AlN作为压电层,制备出了固态装配型FBAR传感器。通过淀积不同厚度Al层顶电极,对器件的质量灵敏度进行了分析,得到质量传感器串联谐振频率在2.8GHz附近,质量响应度达到5×10-4ng/Hz/cm2,可以实现分子量级的质量传感。     

Solidly Mounted Resonators with Ultra-High Operating Frequencies Based on 3R-MoS2 Atomic Flakes

Conventional bulk and thin piezoelectric materials based film bulk acoustic resonators (FBARs) are facing an insurmountable challenge for millimetric frequency applications due to the poor piezoelectric properties of the materials when their thickness reaches the sub-micron regime. Novel FBARs for ultra-high working frequencies are in urgent demand to meet the requirements of the fast-growing 5/6G telecommunication techniques. Recent advances in 2D piezoelectric nanomaterials create an opportunity in this perspective. Here, the first FBAR chip based on 2D 3R-MoS₂ ultrathin piezoelectric flakes with a solidly mounted resonator (SMR) architecture is reported. The typical resonant frequency for an SMR device based on ≈200 nm 3R-MoS₂ flake reaches over 25 GHz with high reproducibility. Theoretical and finite element analysis suggest that the observed resonance is of longitudinal acoustic modes. This study demonstrates for the first time that the access to 2D piezoelectric nanomaterials makes high performance piezoelectric devices feasible for various promising applications including high-speed telecommunication, acousto-optic, and sensor fields,etc.     

压电和铁电薄膜及其应用的发展趋势

本文讨论了压电和铁电薄膜材料及其在固体器件中应用的发展趋势。薄膜生长技术的进展,为压电和铁电薄膜集成固体器件在各个领域的应用开辟了广阔的前景。ZnO和AIN薄膜将广泛地用于SAW和BAW器件。特别是成功地制作了薄膜体声波谐振器和高次谐波体波谐振器。以PbTiO_3为基的PZT和PLZT固溶体外延薄膜将应用于热电探测器和SAW器件。在实现了对多层薄膜的界面结构及其特性的成功控制之后,铁电薄膜将在铁电存储和集成光学领域发挥重要作用。     

薄膜体声波谐振器及其应用

综合阐述薄膜体声波谐振器技术,简要介绍了薄膜体声波谐振器技术及其发展历程,对其物理模型和等效电路模型进行了回顾,对该器件的三种结构和及其制作方法进行了分析,并讨论了其使用的压电材料和电极材料,最后给出了该器件在微波领域的典型应用和相关指标.     

DGS resonator with interdigital capacitor and application to bandpass filter design

A novel defected ground structure (DGS) microstrip resonator is proposed. The proposed DGS resonator has the resonant and anti-resonant characteristic that is very similar to those of a surface acoustic wave resonator or a film bulk acoustic resonator (FBAR). To confirm the validity of the proposed resonator, bandpass filters were designed and implemented using series and parallel resonators.     

薄膜体声波谐振器电极效应研究

运用传输线路法推导了薄膜体声波谐振器(Thin Film Bulk Acoustic Resonator,FBAR)的输入阻抗公式.利用输入阻抗公式,研究了不同材料FBAR构成中电极材料和厚度对FBAR有效机电耦合系数的影响,FBAR最大有效机电耦合系数优化理论.由结论可知,FBAR的有效机电耦合系数随电极的厚度和密度变化明显,在低密度电极材料时,电极厚度增大明显降低了FBAR的有效机电耦合系数;同时,在电极厚度较厚时,电极密度越大越有利于获取高的有效机电耦合系数.所得结论,可应用于FBAR设计与优化中.     

薄膜体声波谐振器调频工艺研究

薄膜体声波器件具有体积小及性能高等优势,相关产品已被广泛应用于移动通信市场。薄膜体声波谐振器(FBAR)电极层和压电层等声学层的厚度、材料是影响谐振频率的主要因素。该文分析了FBAR调频的必要性、原理及扫描刻蚀的工作方式,研究了调频层薄膜在不同刻蚀功率时对器件频率的影响。通过对FBAR器件进行调频,频率均匀性提高了6.5倍,频率分散性得到显著改善。     

An Intrinsically Switchable FBAR Filter Based on Barium Titanate Thin Films

A switchable thin film bulk acoustic wave resonator (FBAR) filter based on barium titanate (BTO) thin films is reported for the first time. BTO is a ferroelectric material which possesses electrostriction, giving the filter the ability to be placed in either an on state or an off state by changing the applied dc bias voltage. A 1.5 stage ladder type bandpass filter using BTO FBARs has been designed, fabricated, and measured. The application of a 15 V dc bias results in the filter being place in an on state with a center frequency of 2.14 GHz, a 40 MHz bandwidth and 6.2 dB of insertion loss. Conversely, the application of a $-$ 3 V dc bias results in the filter being placed in an off state with 15 dB of rejection. This filter is very compact with dimensions of 40 $mu{rm m}$ by 80 $mu{rm m}$.      

Closed-Form Expressions for the Design of Ladder-Type FBAR Filters

Filters based on film bulk acoustic resonators (FBARs) promise to improve the performance of actual filters, however, to the authors' knowledge, their systematic implementation is not straightforward. This letter presents a collection of closed-form expressions for the systematic design of ladder-type filters using FBARs. The procedure is validated against the work of other authors, finding a very good agreement between results     

氧化锌薄膜体声波谐振器的研制

介绍了一种薄膜体声波谐振器和它的制备流程.该谐振器采用氧化锌压电薄膜作为压电材料,通过从硅片背部体刻蚀硅衬底的方法得到谐振器的支持层.为了避免残余应力引起的支持层起皱现象,采用氮化硅/二氧化硅/氮化硅复合膜作为支持层.采用直流磁控溅射的方法制备氧化锌压电薄膜,X射线衍射结果显示,氧化锌压电薄膜C轴择优取向明显,衍射峰半高宽为0.227 3°,显示出较好的结晶质量;扫描电镜观察到氧化锌垂直于薄膜表面的柱形晶粒结构,薄膜表面平整、致密.采用HP8753D射频网络分析仪对该薄膜体声波谐振器样品进行了测试,结果表明,谐振器具有明显的厚度伸缩振动模式,其基频在750 MHz左右,二次谐频在1.5 GHz左右.进一步提高氧化锌压电薄膜的性能,该谐振器可用于射频振荡源和射频前端滤波器中.     

Extraction of material parameters in film bulk acoustic resonator (FBAR) using genetic algorithm

The extraction of material parameters from the given (or measured) input impedance of film bulk acoustic resonators (FBARs) using a genetic algorithm (GA) is proposed. After studying the effect of material parameter changes on impedance responses, resonance characteristics of FBARs are used to extract the material parameters. The extracted result agrees very well with the given material parameters.     

Al薄膜对(002)ZnO/Al/Si结构基片中ZnO薄膜特性影响的实验研究

采用射频磁控溅射法沉积制备了(002)ZnO/A l/Si复合结构。研究了Al薄膜对(002) ZnO/Al/Si复合结构的声表面波器件(SAWD)基片性能影响以及当ZnO 薄膜厚度一定时的Al膜最佳厚度。采用X射线衍射(XRD)对Al和ZnO薄膜进行了结构表征 ,采用 扫描电镜(SEM)对ZnO薄膜进行表面形貌表征,并从薄膜生长机理角度进行了分析。结果 表明,加Al薄膜有利于ZnO薄膜按(002)择优取向生长,并且ZnO 薄膜的结晶性能提高;与(002)ZnO/Si结构基片相比,当Al薄膜 厚为100nm时,(002)ZnO/Al/Si结构中ZnO薄 膜的机电耦合系数提高 了65%。     

Design and Fabrication of ZnO-Based FBAR Microwave Devices for Mobile WiMAX Applications

In this letter, we present the design and fabrication of a novel ZnO-based film bulk acoustic wave resonator (FBAR) microwave devices. The novel FBAR devices employ a new-type of Bragg reflector with very thin chromium (Cr) layer formed between SiO₂ and W films. The Cr layer seems to enhance the adhesion between SiO₂ and W layers. The novel FBAR devices show good return losses (S₁₁) and high Q-factors at the frequency range of 2.7-3.0 GHz. This approach will be very helpful for mobile worldwide interoperability for microwave access applications.     

薄膜体声波谐振器技术

以微加工技术制作的薄膜体声波谐振器以及由它连接组成的滤波器为重点,介绍了其工作原理、结构模型以及相关参数,提出了一种薄膜体声波谐振器设计,并模拟了其构成射频带通滤波器的频率特性。     

体声波滤波器自动布局工具的设计开发

为了实现体声波（BAW）滤波器版图的自动排布和构建滤波器的三维模型,开发了一款体声波滤波器自动布局工具。根据文献提出的BAW梯形滤波器布局设计流程,基于.NET平台,使用C#语言,创建生成滤波器版图的功能界面。根据输入的薄膜体声波谐振器(FBAR)个数和面积大小生成对应的多边形外接圆,通过FBARs的串并联连接情况,生成放置外接圆的位置,并生成多边形。生成多边形后,用户只需对其进行微调(拖动、旋转等),即可在保证滤波器性能的情况下,得到面积尽可能小的版图。在所完成的滤波器版图基础上,根据滤波器的结构参数和建模方式, 在AutoCAD中导入写好的动态链接库,创建生成滤波器三维模型的功能界面。输入FBAR膜层厚度等参数后,软件自动生成滤波器的三维模型。并自动保存为可导入电磁仿真软件的dwg文件或sat文件,方便滤波器的电磁仿真。设计开发过程中所用滤波器的结构参数等即为该文验证所设计软件的案例。证明了所开发软件的可行性。即软件在保证滤波器性能的情况下,最大限度地缩小版图面积,提高滤波器在晶圆上的面积利用率,且节省了滤波器设计人员的时间和精力。     

LiNbO_3单晶薄膜体声波谐振器的研制

该文介绍了一种采用智能截割(Smart Cut~(TM))技术制备的单晶铌酸锂(LiNbO_3)薄膜体声波谐振器。采用COMSOL有限元仿真软件从材料和结构两方面对LiNbO_3薄膜体声波谐振器进行优化设计,以实现高机电耦合系数,并通过Smart Cut~(TM)工艺方法制备了高性能Z切-LiNbO_3单晶薄膜作为谐振器的压电层,最终得到LiNbO_3薄膜体声波谐振器的谐振频率为3 847.5 MHz,反谐振频率为3 986.25 MHz,插入损耗为1.81 dB,谐振器有效机电耦合系数达到8.3%。