Abstract
As the research passion for micro-electromechanical systems (MEMS) continues, many devices have been unveiled in practical industrial applications such as high resolution projection displays, multi-axis accelerometers, high density data-storage disks, ink-jet printing heads, and micro-fluidic control devices. Most of them have been either commercialized or thoroughly reported in the literatures. Among the prominent actuation principles employed in MEMS device, electrostatic actuation has been the dominant method that relies on the forces generated between two conducting electrodes separated by appropriate dielectrics. In this dissertation, fundamental mechanisms for electric breakdown in dielectrics under micron separations have been explored and experimentally investigated. In addition, systematic analysis has been conducted on the basic design and fabrication of micro-electrodes for exploration of electrical breakdown to provide the design guidelines to the industry. In the study, the fundamental approach has been based upon the Paschen’s Law which states the essential parameters on gas pressure and distance of electrodes. For the MEMS applications, single-crystal silicon and impurity-doped silicon were chosen for serving as the basis of design and fabrication of micro-electrodes with various geometric shapes. Initially, experimental results have shown that when the surface roughness was negligible, field emission effects will gradually dominate the breakdown voltage when the gap is smaller than 5 micron on metal electrodes. On the contrary, the breakdown voltage will go higher when the gap is smaller than 5 micron on both pure and doped silicon-electrodes. Not until the surface roughness of the electrodes starts to pick up electric field concentration, the breakdown voltage gradually decrease in a linear manner as the gap shrinks. In conclusions, this study has proposed the design guidelines for electrostatic actuated MEMS devices as well as elucidated a consolidated experimental method for the study of electric breakdown of dielectric gases with micron separations.