横向场激励的压电体声波器件高频振动研究及其应用

The piezoelectric bulk acoustic wave (BAW) devices based on lateral field excitation have obvious advantages on highly sensitive piezoelectric sensors over the traditional thickness field excited devices. However, the exciting pattern results in complicated electric field and displacement distributions. The lack of the vibration analysis methods has influenced directly the determination of the optimal design parameters. As a result, spurious vibration modes and vibration couples between the array elements influnce obviously the performance improvement of the devices.The equations of high frequency vibrations of piezoelectric substrates under lateral field excitation will be established by taking the electric field gradient into account. The model of energy trapping structure for lateral field excited devices will be established to suppress the spurious vibration modes by investigating the energy trapping effect. Besides, the model of the array structure will be established to suppress the vibration couples between the array elements of lateral field excited devices by investigating the coupling mechanism. Then, experimental verifications for the theory results will be done by designing, manufacturing, and testing the piezoelectric sensors under lateral field excitation. The research results will provide reliable analysis method for lateral field excited devices. The new thinkings and methods of suppressing spurious modes will be also provided for the bulk acoustic wave devices with complicated electrode structure. The research is of important significance in promoting the applications of the lateral field excited devices on high-performance piezoelectric sensors.

和传统的厚度场激励体声波器件相比，横向场激励体声波器件在高灵敏压电传感器领域具有独特的优势。然而，其激励模式导致了复杂的电场和位移分布，振动分析方法的缺乏直接影响到最佳设计参数的确定，由此导致的寄生振动模态的出现和阵列器件单元间振动耦合等问题，显著影响到器件性能的提高。本课题通过引入电场梯度效应建立横向场激励压电板的高频振动方程；在此基础上通过研究横向场器件的能陷效应建立抑制器件寄生振动模态的能陷结构模型，并通过探索横向场阵列器件单元间的声波振动耦合机制，建立能抑制单元间振动耦合的阵列结构模型，从而发展横向场激励体声波器件的高频振动分析方法；然后通过设计、制作及测试横向场压电传感器对理论分析方法进行实验验证。研究成果将为横向场激励器件提供可靠的振动分析方法，也可为复杂电极结构声波器件的寄生模态抑制提供新的思路和途径，对促进横向场器件在高性能压电传感器中的应用具有重要意义。

横向场激励体声波器件在高灵敏压电传感器领域具有独特的优势。然而相对于厚度场激励模式，横向场激励模式具有更复杂的电场和位移分布，振动分析方法的缺乏直接影响到最佳设计参数的确定。本课题发展了横向场激励体声波器件的高频振动分析方法，通过设计、制作及测试横向场压电传感器对理论分析方法进行了实验验证。具体完成了以下工作：（1）基于Mindlin板理论，推导出了横向场激励压电板的高频振动方程。（2）通过对横向场激励器件的高频振动特性分析，找到了提高横向场器件能陷效果的方法，发现了极性反转层技术能有效抑制横向场器件的寄生振动模态。（3）通过建立横向场激励阵列器件的高频振动分析模型，研究了横向场阵列器件阵元间声波振动耦合的机制，并有效抑制了阵元间的振动耦合。（4）利用石英、硅酸镓镧、铌酸锂等压电晶体设计制作了横向场压电单体器件和阵列器件。然后对器件谐振特性进行了测试，验证了能陷结构模型对抑制寄生模态、提高谐振特性的有效性。利用阵列器件构建体声波传感器，测试阵列单元间的频率干涉，并与理论结果进行对比，验证了横向场阵列器件高频振动分析方法的有效性。研究成果为横向场激励器件提供了可靠的振动分析方法，也为复杂电极结构声波器件的寄生模态抑制提供了新的思路和途径，对促进横向场器件在高性能压电传感器中的应用具有重要意义。