基于 CMOS 兼容的 AlN/SiO₂/Si 多层结构的基于 VOC 的 Sezawa 模式 SAW 传感器的有限元分析。
FEM Analysis of Sezawa Mode SAW Sensor for VOC Based on CMOS Compatible AlN/SiO₂/Si Multilayer Structure.
机构信息
Department of Electrical and Electronics Engineering, Universiti Teknologi PETRONAS, 32610 Seri Iskandar, Perak, Malaysia.
Department of Mechanical Engineering, Universiti Teknologi PETRONAS, 32610 Seri Iskandar, Perak, Malaysia.
出版信息
Sensors (Basel). 2018 May 24;18(6):1687. doi: 10.3390/s18061687.
A Finite Element Method (FEM) simulation study is conducted, aiming to scrutinize the sensitivity of Sezawa wave mode in a multilayer AlN/SiO₂/Si Surface Acoustic Wave (SAW) sensor to low concentrations of Volatile Organic Compounds (VOCs), that is, trichloromethane, trichloroethylene, carbon tetrachloride and tetrachloroethene. A Complimentary Metal-Oxide Semiconductor (CMOS) compatible AlN/SiO₂/Si based multilayer SAW resonator structure is taken into account for this purpose. In this study, first, the influence of AlN and SiO₂ layers’ thicknesses over phase velocities and electromechanical coupling coefficients (²) of two SAW modes (i.e., Rayleigh and Sezawa) is analyzed and the optimal thicknesses of AlN and SiO₂ layers are opted for best propagation characteristics. Next, the study is further extended to analyze the mass loading effect on resonance frequencies of SAW modes by coating a thin Polyisobutylene (PIB) polymer film over the AlN surface. Finally, the sensitivity of the two SAW modes is examined for VOCs. This study concluded that the sensitivity of Sezawa wave mode for 1 ppm of selected volatile organic gases is twice that of the Rayleigh wave mode.
进行了有限元方法（FEM）模拟研究，旨在研究多层 AlN/SiO₂/Si 声表面波（SAW）传感器中 Sezawa 波模式对低浓度挥发性有机化合物（VOC）的敏感性，即三氯甲烷、三氯乙烯、四氯化碳和四氯乙烯。为此，考虑了一种互补金属氧化物半导体（CMOS）兼容的 AlN/SiO₂/Si 基多层 SAW 谐振器结构。在这项研究中，首先分析了 AlN 和 SiO₂ 层厚度对两种 SAW 模式（即瑞利波和 Sezawa 波）的相速度和机电耦合系数（²）的影响，并选择了最佳的 AlN 和 SiO₂ 层厚度以获得最佳的传播特性。然后，通过在 AlN 表面涂覆一层薄的聚异丁烯（PIB）聚合物膜，进一步扩展了研究以分析 SAW 模式的共振频率对质量负载的影响。最后，研究了两种 SAW 模式对 VOC 的灵敏度。这项研究得出的结论是，所选挥发性有机气体的 1ppm 浓度下，Sezawa 波模式的灵敏度是瑞利波模式的两倍。
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