MEMS动平板的切向静电阻力

Electrostatic Resistance for the Moving Plate in MEMS

由于微机械的表面积与体积之比远大于宏机械,所以微机械中的表面阻力难以忽略,为了改善MEMS器件的性能和可靠性,必须对其影响进行研究.基于能量守衡法,本文建立了光滑平板和正方形、四棱锥两种微凸体粗糙表面平板的切向静电阻力模型,讨论了微小尺度、表面形貌、外加电压以及因流片制造工艺而产生的微凸体、凹坑或孔对两个相对运动的带电平板间的切向静电阻力的影响.分析表明:当平板宽度与两平板之间的距离之比、表面形貌因数和外加电压增大时,切向静电阻力也将随之增加;表面形貌因数则与微凸体在平板的总投影面积与平板面积之比成正比,随相对表面粗糙度增加而非线性增加.

Friction force is present in most microelectromechanical systems （MEMS）, since they have a large surface area to volume ratio. Understanding of friction is necessary to improve the performance and reliability of MEMS. A model of electrostatic tangential force for smooth and two kinds roughness plates, which are square and pyramid asperities, was established based on the energy balance method. The factors of the microscale, superficial appearance, applied voltage, micro asperities or dents or holes needed by fabrication were considered to discuss the electrostatic tangential resistance between two charged moving plates with respect to each other. As the rate of the plate width over the gap between two plates increased or the superficial appearance factor increased, or the applied voltage increased, the electrostatic tangential resistance increased accordingly. The superficial appearance factor was directly proportional to the rate of all micro asperities projective area to the plate area, and nonlinearly increased with increase of the relative surface roughness.