Research On System-Level Modeling And Simulation Of Microelectromechanical Systems

Microelectromechancial systems is a manufacturing technology of multi- discipline which develops rapidly. At present, the high cost and long design cycle of MEMS products restrict the growing due to the comparatively low design level. Thus, the design of methodology MEMS and CAD tools have been great significances in international MEMS researches with important theoretical and applied value. System-level modeling and simulations are the key issues to realize computer-aid virtual design of MEMS. This thesis presents a NODAS (Nodal Design of Acutators and Sensors) library for simulation and design of suspended MEMS. NODAS is a library of a series of low-level elements (2D, 3D beams, nonlinear beams, anchors, plate masses, electrostatic gaps, combs, eletrothermal beams, et al). The lumped parameterized behavioral models are implemented in MAST, which is an analog hardware description language. All the detail model dervations and verification simulations are given. The NODAS simulation of element models showed more than 95% accuracy of ANSYS simulation. In an EDA simulator SABER, system-level simulations of MEMS devices are based on the schematics composed of the MAST elements. A structural parameterized design flow and verification methodology of MEMS based on the MAST elements library are presented. The key issues of this thesis include modeling physics, schematic representation, accuracy verification, application examples. Modeling and system-level simulation based on the MEMS behavioral models enable the structural, electrostatic and thermal multi-field analysis and are compatible with circuit design. With high simulation accuracy and speed, the methodology supports iterative design and evaluation, provides an high-level efficient verification for MEMS design, and ease the optimization of large systems. Study is also made on the the deflection and stability of membrane structures under electrostatic and Casimir forces in MEMS. The effect of the Casimir force on the deflection is analysized. The static stability of the membrane structure can be determined by a dimensionless parameter K related with the geometrical parameters of the membrane. The critical value K C is obtained through numerical calculations and a design method of elelctrostatically driven membrane with a high aspect ratio ( L / h )is presented avoiding the potential instability.