Effect of Electric Fields Generated by Microactuators on the Imaging in Electron Microscopy

In this paper we are investigating the potential to employ small devices in crucial areas with limited volumes in electron microscopes. We present the analysis of the electric fields that are present in an electrostatically actuated micro electro mechanical systems (MEMS) device. The electric fields are modeled using finite elements methods (FEM). Preliminary results are shown from scanning electron microscope (SEM) measurements of an electrostatically actuated two degrees of freedom (2DOF) nanometer precision table. From the FEM results the influence of the electric fields on an electron beam traversing the devices can be calculated. This influence is calculated to be a trajectory displacement in the order of tens of nanometers for typical acceleration voltages. SEM measurements show significant vibrations in the images of nonmovable parts of the devices when applying actuation voltages to the devices. This shows an effect of actuation on the detected electrons while imaging. Deflections up to 2.2 μm have been observed for a voltage of 80 Vpp. This deflection cannot be fully attributed to deflections of the incoming beam. Therefore we include in a qualitative analysis the trajectory of emitted secondary electrons that are detected.