采用牺牲层技术的电容式微机械超声传感器的仿真与分析  

Finite Element Simulation and Analysis of CMUT with Sacrificial Release Techniquies

作　　者：郭庆 李妍 高尚 张培玉 Guo Qing;Li Yan;Gao Shang;Zhang Peiyu(School of Physics and Electronics,Henan University,Kaifeng 475000,Henan,China)

机构地区：[1]河南大学物理与电子学院,河南开封475000

出　　处：《中国生物医学工程学报》2018年第6期705-713,共9页Chinese Journal of Biomedical Engineering

基　　金：国家自然科学基金(61774055);河南省自然科学基金(162300410033);河南省科技厅产学研项目(162107000039)

摘　　要：电容式超声传感器有可能取代压电式超声传感器,在超声成像领域受到极大的关注。目前,对采用牺牲层释放技术加工而成的电容式微机械超声传感器(CMUT)的分析,均较少将释放工艺对其结构参数的影响进行详细的分析,故拟将牺牲层释放工艺对CMUT参数的影响进行分析。采用大型工程有限元分析软件ANSYS进行有限元分析的方法,分析释放方法对CMUT性能的影响。采用激光测振仪对超声传感器的共振频率为2.5 MHz的结构进行初步测试,实验结果和仿真结果的误差为3.9%。由仿真分析可知,CMUT振动膜的长宽比对4种CMUT的分析误差变动较大,一般情况下,当振动薄膜的长宽比大于4时,CMUT的振动频率变化不大,且4种模型的相对误差变化趋于平缓。此外,CMUT薄膜的厚度越薄,百分比差异越小。由此得知,牺牲层释放工艺对CMUT的性能有较大的影响,CMUT中支撑振动薄膜的侧墙和牺牲层的释放孔及释放通道对模型仿真有较大的影响。对采用牺牲层技术制造的CMUT,在设计和构建CMUT结构时,应考虑牺牲层释放工艺对CMUT性能的影响。实验结果和仿真结果具有很好的一致性,验证所提模型的有效性。Capacitive micromachined ultrasonic transducers (CMUTs) have attracted great attentions in the field of ultrasonic imaging, because the potential of as alternative to piezoelectric ultrasonic sensors. At present, the analysis on CMUTs built by sacrificial layer release technology has less been involved in the analysis of the influence of the processing structures resulted from the releasing process. In this paper, the influence of sacrificial layer release process on CMUTs was analyzed. The finite element analysis software ANSYS was used to analyze the effect of release method on CMUTs’ performance. Moreover, the CMUT with 2.5 MHz was tested using Vibrometer. The results of both simulation and experiment are considerable consistency with an error of 3.9%. It was concluded that the ratio of length and width of membrane on property of CMUT varied much. The resonant frequency of CMUT changed less and the value of percent difference among four modes vary smoothly when the ratio was larger than 4. In addition, the thinner the thickness, the smaller the percentage difference. The effects of supporting walls on vibrating membrane, releasing holes and channels should be considered when building models on CMUT with sacrificial release technique. Finally, the CMUT with 2.5 MHz was tested using a Vibrometer. The results of both simulation and experiment were considerable consistency, which verified the validity of the model presented in this paper.

关 键 词：电容式微机械超声传感器 共振频率 有限元仿真 生物MEMS 

分 类 号：R318[医药卫生—生物医学工程]