Characteristics Of Micro / Nanoelectromechanical Resonators

Recently years, Micro-Electro-mechanical system (MEMS) is commonly used in many kinds of field, and so it attracts much interests of researchers. Resonator is the most attractive system in the MEMS sensor. With the reducing of the device's scale, Nano-Electro-mechanical system (NEMS) resonators are also been widely researched.We choosed several kinds of resonators, which were designed and fabricated by ourselves. There are included three different structures, which are cantilever-mass system, folding beam-mass system with micrometer scale and clamped-clamped beam system with nanometer scale.Main contents and features of this thesis are as follows:The foundation theory and the structure of the MEMS/NEMS resonators were studied systematically. MEMS resonators are electrostatically driven and piezoresistively detected. The bending vibration equation of the sensor part of all the resonators were calculated, and the piezoresistively were also estimated. The current of the clamped-clamped beam of NEMS resonator, which was designed based on the theory of the MOSFET, is analysed. When the beam is vibrating, the gate voltage must be calculated to the effective gate voltage. So the equivalent gate voltage is studied, and systematically simulated.The features of all the MEMS resonators were measured, included their static state and dynamic state. The piezoresistive effect of cantilever-mass system and the folding beam-mass system is 6%o and 1.8%o respectively. And quality factor as high as 4834 when the resonator frequency is 10.635kHZ for the first system when they are measured under 16mpa vacuum. For the second system, those parameters are 258 and 20.816kHZ.The MOSFET features of the NEMS resonator were proved. The experiment results indicated that the NEMS resonators are stable in the vacuum but it's not so in the circumstance of air. In addition, resonator was easily been destroyed when the control voltage was sostenuto on . In order to eliminate the influence of the coupling signal, a down-mixing signal detection method was proposed, and then it was proved feasible.The radiation damage experiments, when the MEMS resonators were exposed to the electron and γ-rays, shows that the mechanical characteristic and the frequency spectrum of the resonators are sensitive to the radiation dose. The resonatorfrequency reduced when the dose of γ-rays increasing.Based on the research and experiments, the dynamic features of the MEMS resonators are successfully obtained. And the NEMS resonators also showed the MOSFET effects. The results could be the reference of the MOSFET effect detection. The radiation test results also provided the theory and factual gist.