Simulation And Study Of A New-type Micro-electromechanical Systems Resonator

One of the best features of Micro-electromechanical Systems(MEMS) resonator is the high quality factor. A new kind of resonator, thin-film piezoelectric on silicon(TPoS) MEMS resonators utilize piezoelectric effect to drive and doped single silicon to conduct. Because thick single silicon layer could provide high energy density, so it owns higher quality factor than the other kinds of piezoelectric resonators. But there comes a lot of questions waiting to be solved.In this thesis, a 10 MHz TPoS resonator that works at length-extensional mode is designed, simulated and fabricated. The working mechanisms and characteristics of TPoS resonators are analyzed as well. The innovation point part of this thesis is to improve the resonator’s supporting structure to reduce the anchor loss. And some other relevant works including modeling the equivalent circuit, test and package are also presented.It has been acknowledged that the detailed theoretical model is indispensable to for the TPoS resonator’s simulation and analysis. Importantly the equivalent circuit model of the resonator is firstly built in this work. Then some important parameters, such as sensitivity, are proposed and discussed based on the theoretical model. And, the feasible analysis of the resonator is verified by the simulation tool(Automation Device Specification). All of these works form the solid foundation for the next.To enhance the performance of the resonator, the mechanism of several kinds of energy dissipation in the resonator are discussed. It has been confirmed that the anchor loss has been the main stream. The finite element analysis software COMSOL Multiphysics is employed in simulating the anchor loss of different kinds of supporting structures. And etching trenches as reflectors is proposed to reduce the anchor loss. All dimensions of this novel structure are discussed and optimized by combining the simulated results. The simulation results also further verify the source and mechanism of the anchor loss.The fabricating processes are discussed in details and determined finally based on the simulation result of the whole device. The device is fabricated successfully. Considering the influence of bonding and package, the transmission loss of the resonator has been measured twice before and after packaging.The final test result shows that the fabricated resonator works at 10.0175 MHz. The quality factor and insertion loss are 3130 and-31.2 dB respectively. The phase shifting at the peak is-185 degree. All the parameters meet the requirements. At the same time, a series of important points has been clarified, like: How to design and demonstrate? How to enhance the efficiency more deep? What is revolutionary fabrication? What is the best testing methods and capsulation. By solving these questions, our word have made a basis foundation for next job.