Abstract
This paper presents an Aluminum Nitride (AlN) Lamb-wave resonator with high series-resonance quality factors (Qs) and good spectral purity. The influence of the interdigitated (IDT) electrode width and electrical boundary condition was theoretically analyzed to improve effective electro-mechanical coupling coefficient (k2eff) and spectral purity. According to the structural characteristic of the designed resonators, an advanced micro-manufacturing process was designed. A thermal oxide layer was employed to avoid the etching of inactive regions, which contributes to achieving the high Qs and high-yield fabrication. The measured results show the IDT-ground resonators with 12 μm and 6 μm electrode periods exhibit Qs values as high as 4457.1 and 2625.1, and k2eff of 0.61% and 0.33%, respectively. The IDT-IDT resonators have higher k2eff, but their Qs values are severely attenuated. Through observing their section morphologies, the measured shear angles of the bottom IDT electrodes with 12 μm and 6 μm periods are 54.95° and 65.7° respectively, and the surface AlN film has tiny cracks, which induces the performance deterioration of the IDT-IDT resonators. Moreover, the influence of the IDT material on the resonator’s performance was also analyzed.
Published Version
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