MEMS电容型器件边缘效应研究

MEMS电容型器件在工作过程中,其电容通常情况下为非正对的极板,边缘效应不容忽视。为解决此问题,基于保角映射变换和复变函数相关理论,通过继承传统模型并加以修正,得出电容极板在非正对情况下的边缘效应模型。经过与有限元仿真、传统Heerens模型、Huang模型的对比,表明当电容极板从正对到完全移开的过程中,本文模型与有限元仿真的误差在10%~20%之间,优于传统Heerens模型与Huang模型。进一步,根据本文模型,当极板重合度低于40%时,边缘效应呈快速增长,此时其电容值可用本文模型进行计算。以上结论均得到了MEMS阵列电容数字式实验验证。研究对电容型MEMS器件的设计与性能分析具参考作用。

FEM Edge Effect and Capacitance Evaluation on Cylindrical Capacitors

The purpose of this paper is to show the influence of the edge-effect on the electric field distribution, and hence on the inner capacitance and outer capacitance of a cylindrical capacitor surrounded by an insulating medium. To generalize the results, a two-dimensional axisymmetric finite element model of a cylindrical capacitor has been generated and the problem has been resolved taking into account the distance between the conductors for a complete set of dimensions. The available obtained results have been compared with previous published works. Finally, using statistical tools, the mathematical expression for computing the relationship between capacitance and insulation gap and cylindrical plates dimensions has been obtained.