Experimental investigation of acoustic substrate losses in 1850-MHz thin film BAW resonators
Experimental investigation of acoustic substrate losses in 1850-MHz thin film BAW resonators
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1850 MHz 薄膜体声波谐振器中声学基板损耗的实验研究
DOI：
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发表时间：
2009
期刊：
影响因子：
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通讯作者：
J. Kaitila
中科院分区：
文献类型：
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作者：
T. Pensala;R. Thalhammer;James Dekker;J. Kaitila
在对机电耦合系数K2进行优化后，薄膜体声波谐振器和滤波器的主要性能改进可以通过提高Q值来实现，即使损耗最小化。在基于bragg反射器的固体安装谐振器技术中，通过优化反射器，不仅可以针对预期的工作模式纵波，还可以针对横波，实现了Q的显著改进。我们通过去除谐振器下方的衬底，并通过去除衬底前后的电学特性比较有衬底和没有衬底的器件，研究了如此优化的1850-MHz AlN谐振器中衬底的剩余声辐射损失。比较了几种提取谐振器q值的方法。在谐振器的行为中观察到衬底去除引起的变化，但可以确认q值没有显着改善。除衬底泄漏外，损耗机制是影响谐振腔q值的主要因素。还讨论了检测谐振器q值微小变化的困难。
After optimizing for electromechanical coupling coefficient K2, the main performance improvement in the thin film bulk acoustic wave resonators and filters can be achieved by improving the Q value, i.e., minimizing the losses. In Bragg-reflector-based solidly mounted resonator technology, a significant improvement of Q has been achieved by optimizing the reflector not only for longitudinal wave, the intended operation mode, but also for shear waves. We have investigated the remaining acoustic radiation losses to the substrate in so-optimized 1850-MHz AlN resonators by removing the substrate underneath the resonators and comparing the devices with and without substrate by electrical characterization before and after the substrate removal. Several methods to extract Q-values of the resonators are compared. Changes caused by substrate removal are observed in resonator behavior, but no significant improvement in Q-values can be confirmed. Loss mechanisms other than substrate leakage are concluded to dominate the resonator Q-value. Difficulties of detecting small changes in the Q-values of the resonators are also discussed.