AlN薄膜压电微机械超声换能器的设计与优化

doi:10.19665/j.issn1001-2400.2020.03.002

摘要/Abstract

摘要：

由于现有的超声换能器多以锆钛酸铅$Pb(Z_{r_{1-x}}Ti_{x})O_{3})$和氧化锌(ZnO)材料为压电薄膜,而锆钛酸铅(PZT)含铅,氧化锌存在污染互补金属氧化物半导体制造的问题,对此设计了以氮化铝材料作为压电层的圆形双叠片弯曲振动压电超声微机械换能器。对换能器工作原理进行了分析,建立了有限元模型,针对换能器的尺寸参数进行了有限元仿真。研究发现,换能器谐振频率与各层厚度成正比,与换能器半径的平方成反比;当上电极半径为换能器半径的65%左右时,换能器的谐振振幅最大;当振动层硅和压电层氮化铝的厚度比为0.6左右时,其谐振振幅也最大。对优化后的换能器进行仿真,并与原模型进行了对比。结果表明,空气中的工作频率为9.21MHz,机电耦合系数在空气中从21.44%提高至27.16%,在水中从3.55%提高至11.93%。这些结论为医疗成像探头的研究提供了基础数据。

关键词: 压电微机械超声换能器, 氮化铝, 有限元分析, 性能优化

Abstract:

Because existing ultrasonic transducers mostly use PZT and ZnO materials as piezoelectric thin films, while the PZT contains lead and ZnO has the problem of contaminating CMOS manufacturing, a piezoelectric ultrasonic micromechanical transducer with circular bi-laminate bending vibration which uses the aluminium nitride as the piezoelectric layer is designed. The working principle of the transducer is analyzed, the finite element model is established, and the finite element simulation is carried out for the size parameters of the transducer. It is found that the resonant frequency of the transducer is proportional to the thickness of each layer and inversely proportional to the square of the radius of the transducer; when the radius of the upper electrode is about 65% of the radius of the transducer, the resonant amplitude of the transducer is the largest; when the thickness ratio of the silicon and the aluminum nitride of the piezoelectric layer is about 0.6, the resonant amplitude is also the largest. The optimized transducer is simulated and compared with the original model. The results show that the working frequency in air is 9.21MHz, the electromechanical coupling coefficient increases from 21.44% to 27.16% in air and from 3.55% to 11.93% in water. These conclusions provide basic data for the research on the medical imaging probe.

Key words: piezoelectric micro-machined ultrasonic transducer, AlN, finite element analysis, performance optimization

中图分类号:

TB552

娄利飞,赵建新,梁雅楠,赵明阳,安再芳. AlN薄膜压电微机械超声换能器的设计与优化[J]. 西安电子科技大学学报, 2020, 47(3): 8-13.

LOU Lifei,ZHAO Jianxin,LIANG Ya’nan,ZHAO Mingyang,AN Zaifang. Design and optimization of the piezoelectric micromechanical ultrasonic transducer with an AlN thin film[J]. Journal of Xidian University, 2020, 47(3): 8-13.

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