铁电薄膜可调微带带通滤波器的研制
发布时间：2018-10-04 20:02
【摘要】：微波滤波器作为现代通信系统必不可少的元件,广泛应用于移动通信、雷达、卫星定位与导航、电子对抗、无线遥感等领域。随着电磁环境越来越复杂和频道越来越拥挤,有限的频谱资源已无法满足人们日益增加的需求。基于BST铁电薄膜的可调滤波器因其调谐速度快、体积小、与微电子工艺兼容且适应于多频道等优点而越来越得到重视。因此,本文设计并制作了一种铁电薄膜可调微带带通滤波器。研究内容和主要结论如下:1、采用射频磁控溅射在单晶蓝宝石基片上制备了BST铁电薄膜。针对基片与薄膜热膨胀系数不同,改进了薄膜的退火工艺,避免了薄膜表面出现微裂纹的现象。利用MIM电容结构,测试了BST铁电薄膜的C-V特性曲线,确定了BST铁电薄膜的介电常数为185.5,损耗小于0.02,介电系数可调率为45%等参数。2、根据教研室已有的微波器件设计经验和方法,得出滤波器的主要设计参数。设计了5阶梳状线带通滤波器,并采用平面电路仿真软件ADS和三维电磁场仿真软件HFSS对器件进行仿真。仿真结果显示其中心频率为900MHz,3dB带宽约为10%,带内插损小于2dB(不考虑薄膜介电损耗),带外抑制小于-50dB,中心频率附近电压驻波比小于1.25。3、研究了铁电薄膜可调微带带通滤波器的详细制备工艺流程,着重分析了光刻工艺图形化BST薄膜介质层和上电极的过程及电镀加厚的工艺过程中,工艺误差对器件性能的影响。在蓝宝石基片上成功制作出了可调带通滤波器,并封装测试。对比仿真结果,器件的中心频率偏移到1.15GHz,插损大于13d B,较设计有所偏大,其他性能满足设计要求。在10V和20V直流偏压下,器件的中心频率较未加电压时分别向高频方向移动了70MHz和180MHz,调谐率为14.6%。4、优化了器件的结构,研究了器件表面电磁场分布。利用原有结构,仅改变了调谐电容部分,就几乎消除了BST铁电薄膜的损耗对器件插入损耗的影响。运用器件表面电磁场的动态分布分析了产生该现象的原因。最后,研究了如何优化器件制作工艺以提高器件的性能。
[Abstract]:As an indispensable component of modern communication system, microwave filter is widely used in the fields of mobile communication, radar, satellite positioning and navigation, electronic countermeasure, wireless remote sensing and so on. As the electromagnetic environment becomes more and more complex and channels become more and more crowded, the limited spectrum resources can no longer meet the increasing demand. The tunable filter based on BST ferroelectric thin film has been paid more and more attention because of its high tuning speed, small size, compatible with microelectronic technology and suitable for multi-channel. Therefore, a tunable microstrip band-pass filter for ferroelectric thin films is designed and fabricated. The main conclusions are as follows: 1. BST ferroelectric thin films were deposited on sapphire substrates by RF magnetron sputtering. In view of the difference of thermal expansion coefficient between substrates and thin films, the annealing process of thin films is improved to avoid the phenomenon of microcracks on the surface of the films. The C-V characteristic curves of BST ferroelectric thin films are measured by using MIM capacitor structure. The dielectric constant of BST ferroelectric thin films is 185.5, the loss is less than 0.02, and the dielectric coefficient is adjustable to 45%. According to the experience and methods of microwave device design in the teaching and research department, the dielectric constant of BST ferroelectric thin films is determined. The main design parameters of the filter are obtained. The fifth order comb line bandpass filter is designed. The planar circuit simulation software ADS and the 3D electromagnetic field simulation software HFSS are used to simulate the device. The simulation results show that the center frequency is 900MHz ~ (3) dB bandwidth is about 10, the band insertion loss is less than 2dB (without considering the dielectric loss of the film), the out-of-band suppression is less than -50 dB, and the voltage standing wave ratio near the center frequency is less than 1.25.3. The tunable microstrip bandpass filter of ferroelectric thin film is studied. The detailed preparation process of the wave device, The effect of process error on the performance of BST thin film dielectric layer and upper electrode in photolithography process and the process of electroplating thickening are emphatically analyzed. A tunable bandpass filter is successfully fabricated on sapphire substrate and tested. Compared with the simulation results, the center frequency of the device is shifted to 1.15GHz, and the insertion loss is more than 13dB, which is larger than the design, and other performances meet the design requirements. At 10V and 20V DC bias, the center frequency of the device moves to the high frequency direction 70MHz and 180MHz, respectively, and the tuning rate is 14.60.4.The structure of the device is optimized and the electromagnetic field distribution on the surface of the device is studied. The influence of the loss of the BST ferroelectric thin film on the insertion loss of the device is almost eliminated by changing the tuning capacitance part of the original structure. The cause of this phenomenon is analyzed by using the dynamic distribution of electromagnetic field on the surface of the device. Finally, how to optimize the fabrication process to improve the performance of the device is studied.
【学位授予单位】：电子科技大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TN713.5
[Abstract]:As an indispensable component of modern communication system, microwave filter is widely used in the fields of mobile communication, radar, satellite positioning and navigation, electronic countermeasure, wireless remote sensing and so on. As the electromagnetic environment becomes more and more complex and channels become more and more crowded, the limited spectrum resources can no longer meet the increasing demand. The tunable filter based on BST ferroelectric thin film has been paid more and more attention because of its high tuning speed, small size, compatible with microelectronic technology and suitable for multi-channel. Therefore, a tunable microstrip band-pass filter for ferroelectric thin films is designed and fabricated. The main conclusions are as follows: 1. BST ferroelectric thin films were deposited on sapphire substrates by RF magnetron sputtering. In view of the difference of thermal expansion coefficient between substrates and thin films, the annealing process of thin films is improved to avoid the phenomenon of microcracks on the surface of the films. The C-V characteristic curves of BST ferroelectric thin films are measured by using MIM capacitor structure. The dielectric constant of BST ferroelectric thin films is 185.5, the loss is less than 0.02, and the dielectric coefficient is adjustable to 45%. According to the experience and methods of microwave device design in the teaching and research department, the dielectric constant of BST ferroelectric thin films is determined. The main design parameters of the filter are obtained. The fifth order comb line bandpass filter is designed. The planar circuit simulation software ADS and the 3D electromagnetic field simulation software HFSS are used to simulate the device. The simulation results show that the center frequency is 900MHz ~ (3) dB bandwidth is about 10, the band insertion loss is less than 2dB (without considering the dielectric loss of the film), the out-of-band suppression is less than -50 dB, and the voltage standing wave ratio near the center frequency is less than 1.25.3. The tunable microstrip bandpass filter of ferroelectric thin film is studied. The detailed preparation process of the wave device, The effect of process error on the performance of BST thin film dielectric layer and upper electrode in photolithography process and the process of electroplating thickening are emphatically analyzed. A tunable bandpass filter is successfully fabricated on sapphire substrate and tested. Compared with the simulation results, the center frequency of the device is shifted to 1.15GHz, and the insertion loss is more than 13dB, which is larger than the design, and other performances meet the design requirements. At 10V and 20V DC bias, the center frequency of the device moves to the high frequency direction 70MHz and 180MHz, respectively, and the tuning rate is 14.60.4.The structure of the device is optimized and the electromagnetic field distribution on the surface of the device is studied. The influence of the loss of the BST ferroelectric thin film on the insertion loss of the device is almost eliminated by changing the tuning capacitance part of the original structure. The cause of this phenomenon is analyzed by using the dynamic distribution of electromagnetic field on the surface of the device. Finally, how to optimize the fabrication process to improve the performance of the device is studied.
【学位授予单位】：电子科技大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TN713.5
【共引文献】
相关期刊论文 前10条
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2 赵静,李泽宏,张波,杨邦朝,翟向坤;一种低成本高密度的高速数模混合微系统集成[J];半导体技术;2004年12期
3 李树，
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