Design And Optimization For Structure Parameters Of MEMS Device On Process Deviation

As performance of MEMS device has greater dependence on the manufacturing process, so it is necessary to apply the idea of DFM into the design and manufacture of MEMS. DFM is short of design for manufacture, which takes the process deviation affecting the performance and yield into comprehensive consideration. The effects of process deviation can be offset in the way of making compensation design of structure parameters in advance. Then, the synchronism between process and design is achieved.This paper chooses the beam and comb structure of MEMS device as the research objects, which are important basic functional unit in MEMS. Their properties, such as resonant frequency value, are function of physical parameters, structural parameters and cross-section shape, which are very important to engineering design. Except for the physical parameter deviation, the main process deviation is the structural parameter deviation and the deformation of cross-section shape. This paper studied the effect of process on the resonance frequency, including the inclination profiles in DRIE process (trapezium effect), over etching by Footing effects and corrugated profiles in TDME process (ripple effect). Aimming at the effects caused by these processes, this paper has built the modified model of the resonance frequency.For beam structure of MEMS devices, the modified model of the beam in the longitudinal or lateral movement has been built, respectively, based on single process effect and multiple effects. On the platform of ANSYS workbench 14.5, clamped beam was simulated to verify the modified model of the beam in longitudinal motion under different process deviation. Similarly, cantilever beam was simulated to verify the modified model of the beam in lateral motion. In conclusion, the modified model of different motion is suitable for both clamped and cantilever beam.For comb structure of MEMS devices, the modified model of comb resonator has been built based on the model of beam in lateral movement. Also, the results were verified by the simulation results of ANSYS workbench 14.5.With the modified model, the ideal SPICE equivalent circuit model of the three types of devices has been modified and the results was turn out to be true. Besides, the way to reduce the influence of the uncertainty factors has been put forward according to the process effects and the compensation design has been realized by making use of the existing design optimization algorithm. The software for interface’s design from devices’ parameters to corresponding optimization algorithms is developed with C++, which is introduced in detail in this paper.This paper has briefly showed the method of DFM applied into the automatic optimization for resonance frequency of MEMS device, which provided the thought and basis for the design of MEMS.