Measurement And Mode Analysis Of Microvibration Based On Heterodyne Interferometry

MEMS devices feature a variety of good qualities such as high Q value at high frequencies,low power consumption and high sensitivity,which allow them to fulfill the demanding specifications for today’s electronic applications and drive a great number of researchers to devote themselves to this field.High performance film bulk acoustic resonators and micro-cantilevers are significant MEMS devices with very good application prospects in RF and sensing areas.The design,fabrication and characterization of MEMS devices demand the support of MEMS testing technology.However the existing testing methods are not yet perfect,the accuracy,measuring speed,measuring bandwidth and measurement range still need to be optimized.To address the need for the characterization of nano-scale vibrations,a testing method with high sensitivity should be developed.The research summarized in this thesis focuses on the following key points:1.The background and development status of MEMS dynamic characterization at home and abroad are reviewed,and the measurement methods are discussed and summarized carefully.Accordingly the research methods and the testing system in this project are determined.2.A MEMS vibration mode measurement system with the frequency range from several tens of hertz to 12 GHz and the amplitude range from about 1pm to 10 nm is presented on the basis of heterodyne interferometry.3.Vibration mode test is conducted on FBAR and micro-cantilever.The role of dynamic testing in studying the mechanical characteristics of MEMS devices is discussed.The first 6 resonances of the micro-cantilever are simulated using ANSYS finite element analysis software which show good consistency with the testing result.The reason why some torsional modes with an antisymmetrical displacement referred to the line of symmetry along the longest side of t he cantilever are excited is also discussed in this thesis.Compared with the previous measurement methods,the MEMS vibration modal measurement system presented in this project can fulfill the measure ment requirements of high measurement bandwidth and high sensitivity,which is a progress in testing technology.