鐵電薄膜可調(diào)微帶帶通濾波器的研制
發(fā)布時間：2018-10-04 20:02
【摘要】：微波濾波器作為現(xiàn)代通信系統(tǒng)必不可少的元件,廣泛應(yīng)用于移動通信、雷達、衛(wèi)星定位與導航、電子對抗、無線遙感等領(lǐng)域。隨著電磁環(huán)境越來越復(fù)雜和頻道越來越擁擠,有限的頻譜資源已無法滿足人們?nèi)找嬖黾拥男枨蟆；贐ST鐵電薄膜的可調(diào)濾波器因其調(diào)諧速度快、體積小、與微電子工藝兼容且適應(yīng)于多頻道等優(yōu)點而越來越得到重視。因此,本文設(shè)計并制作了一種鐵電薄膜可調(diào)微帶帶通濾波器。研究內(nèi)容和主要結(jié)論如下:1、采用射頻磁控濺射在單晶藍寶石基片上制備了BST鐵電薄膜。針對基片與薄膜熱膨脹系數(shù)不同,改進了薄膜的退火工藝,避免了薄膜表面出現(xiàn)微裂紋的現(xiàn)象。利用MIM電容結(jié)構(gòu),測試了BST鐵電薄膜的C-V特性曲線,確定了BST鐵電薄膜的介電常數(shù)為185.5,損耗小于0.02,介電系數(shù)可調(diào)率為45%等參數(shù)。2、根據(jù)教研室已有的微波器件設(shè)計經(jīng)驗和方法,得出濾波器的主要設(shè)計參數(shù)。設(shè)計了5階梳狀線帶通濾波器,并采用平面電路仿真軟件ADS和三維電磁場仿真軟件HFSS對器件進行仿真。仿真結(jié)果顯示其中心頻率為900MHz,3dB帶寬約為10%,帶內(nèi)插損小于2dB(不考慮薄膜介電損耗),帶外抑制小于-50dB,中心頻率附近電壓駐波比小于1.25。3、研究了鐵電薄膜可調(diào)微帶帶通濾波器的詳細制備工藝流程,著重分析了光刻工藝圖形化BST薄膜介質(zhì)層和上電極的過程及電鍍加厚的工藝過程中,工藝誤差對器件性能的影響。在藍寶石基片上成功制作出了可調(diào)帶通濾波器,并封裝測試。對比仿真結(jié)果,器件的中心頻率偏移到1.15GHz,插損大于13d B,較設(shè)計有所偏大,其他性能滿足設(shè)計要求。在10V和20V直流偏壓下,器件的中心頻率較未加電壓時分別向高頻方向移動了70MHz和180MHz,調(diào)諧率為14.6%。4、優(yōu)化了器件的結(jié)構(gòu),研究了器件表面電磁場分布。利用原有結(jié)構(gòu),僅改變了調(diào)諧電容部分,就幾乎消除了BST鐵電薄膜的損耗對器件插入損耗的影響。運用器件表面電磁場的動態(tài)分布分析了產(chǎn)生該現(xiàn)象的原因。最后,研究了如何優(yōu)化器件制作工藝以提高器件的性能。
[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.
【學位授予單位】：電子科技大學
【學位級別】：碩士
【學位授予年份】：2015
【分類號】：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.
【學位授予單位】：電子科技大學
【學位級別】：碩士
【學位授予年份】：2015
【分類號】：TN713.5
【共引文獻】
相關(guān)期刊論文 前10條
1 鐘福如;陳鳳;田敏;張衛(wèi)東;;超寬帶1∶4Wilkinson功率分配器的設(shè)計[J];半導體光電;2010年05期
2 趙靜,李澤宏,張波,楊邦朝,翟向坤;一種低成本高密度的高速數(shù)模混合微系統(tǒng)集成[J];半導體技術(shù);2004年12期
3 李樹，
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