Research On Aluminum Nitride Lamb Wave MEMS Resonators For Filters And Sensors Applications

This paper reports on the design and fabrication of MEMS Lamb wave resonators(LWRs), band-pass filters and sensors that are based on the resonators. MEMS Lamb wave resonators are novel type piezoelectric resonators, which are compatible with the integrated circuits and are promising to achieve multi-frequency devices on a single wafer. They have high quality factors and can be employed for oscillators, filters and sensors applications. Therefore, research on them is widely developed.Firstly, this work presents the principle of operation of Lamb wave resonators, after which the design and fabrication of them are investigated. It discloses that the resonator geometry has a great impact on the Figure of Merit and there exists an optimized value of the geometric parameters for the best design. Based on this principle, this work designs and fabricates intermediate frequency narrow band filters, which present a low insertion loss and steep roll-off.Next, this work further optimizes the filter design. Cascaded with a pair of capacitors and inductors, the filters succeed in being well matched to 50 ohm radio frequency(RF) systems. Furthermore, Lamb wave filters are integrated with the capacitors, thus contributing to greater size savings and circuit simplification.In addition, this work investigates the resonators for sensors applications, especially their response in liquid environment. In order to alleviate the deterioration of the resonator performance induced by the liquid, we integrated the resonators with micro channels. This technique not only contributes to significant sample savings, but also preserves the quality factor of the resonators, which means a much smaller detection of limit and higher sensitivity can be guaranteed.