微机电系统中薄膜结构在静电力和Casimir力作用下的稳定性

研究了静电驱动的微机械薄膜的稳定性问题。当微机械构件之间的间距在亚微米尺度以下，构件会受到量子效应的影响，如Casimir效应。通过对薄膜在静电力及Casimir力共同作用下的行为进行分析，由数值计算得到了决定薄膜稳定性状态的无量纲参数K及K曲线的临界值Kc，若K值大于Kc，薄膜结构为不稳定，会引起塌陷失效，薄膜粘附在基底上，且不可恢复。Kc值大小与微机械薄膜和基底表面的距离以及外加电压相关。由此提供了设计高长厚比(L／h)的静电驱动薄膜结构的方法，使其不产生失稳塌陷的失效。

Stability of Membrane Structures Under Electrostatic and Casimir Forces in Microelectromechanical Systems

The stability of a driven electrostatically microfabricated rectangular membrane strip is nume-rically analyzed. The structure is regarded as a sub-micron capacitor together with its substrate. The attractive Casimir force between the conducting surfaces as a quantum effect over range of sub-micrometer is considered together with the electrostatic force. The stability of the membrane structure is determined by a dimensionless parameter K related with the geometrical parameters of the membrane structure. The solution for the critical value K C, on which the system is unstable and the membrane strip collapses to the substrate, is obtained. It is found that a membrane structure can be designed to avoid the potential instability with a high aspect ratio (L/h).