Characterization of MEMS devices on the basis of their frequency response function (FRF)

A characterization method for MEMS devices based on the combination of measurement and simulation results is introduced with an example of an electrostatically actuated micro mirror array. The aim of this method is to determine geometrical parameters and built-in mechanical stress is on the basis of the measured Eigen frequencies. A Laser Doppler interferometer and a signal analyzer are used to determine the frequency response function of the micro mechanical structure to calculate the Eigen frequencies. For the numerical simulation of the micro mirrors behavior the finite element model is used and a series of nonlinear coupled-field analysis and pre-stressed modal non linear analysis have been performed. The dependence of the Eigen frequencies on geometrical parameters and built-in mechanical stress is obtained. The method investigated in this thesis is very efficient because it determines several characteristics of a MEMS device on the base of only one measured frequency response function. The work in this thesis demonstrates that a sufficient accuracy is achieved in the measurement of MEMS parameters that cannot be obtained from common measurements methods.