Acoustic dispersion of solidly mounted resonators with an optimized reflector stack for dual wave reflection

2010 IEEE International Ultrasonics Symposium Pub Date : 2010-10-11 DOI:10.1109/ULTSYM.2010.5935642

S. Jose, R. Hueting, A. Jansman

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引用次数: 2

Abstract

Spurious resonance suppression in Bulk Acoustic Wave (BAW) resonators is essential for achieving excellent filter characteristics. These spurious resonances are undesired resonances caused by the finite device edges. The type I mode is the preferred dispersion response for "spurious modes" suppression, since it allows for the direct use of the frame region as the edge termination of the device. In this work we present a novel analytical approach to adjust the dispersion response in a desired way for various material combinations. By employing the diffraction grating method (DGM), which provides dual wave reflection after tailoring the layer stack thickness analytically, we obtain a type I dispersion curve despite the use of a type II piezoelectric material for the resonator. The dispersion response was verified from analytical impedance curves and FEM simulations. The reason for this type of response can be the inherent thicker top-oxide layer. A transmission of −37dB is maintained for longitudinal waves whereas shear waves reach value below −22 dB for a five layer SiO2/W stack, while for a three layer SiOC/Pt (935/555nm) stack −36dB and −24dB is obtained, respectively.

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具有优化的双波反射器堆栈的固体安装谐振器的声色散

体声波(BAW)谐振器中的杂散共振抑制是实现良好滤波特性的必要条件。这些伪共振是由有限的器件边缘引起的不希望的共振。I型模式是“杂散模式”抑制的首选色散响应，因为它允许直接使用帧区域作为设备的边缘终止。在这项工作中，我们提出了一种新的分析方法来调整色散响应在不同的材料组合所需的方式。采用衍射光栅法(DGM)，在解析地调整层堆叠厚度后提供双波反射，尽管使用II型压电材料作为谐振器，但我们获得了I型色散曲线。通过分析阻抗曲线和有限元模拟验证了色散响应。这种响应的原因可能是固有的较厚的顶部氧化层。在5层SiO2/W叠加下，纵波的透射率为- 37dB，而横波的透射率为- 22 dB以下，而在3层SiOC/Pt (935/555nm)叠加下，纵波的透射率分别为- 36dB和- 24dB。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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2010 IEEE International Ultrasonics Symposium

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