Abstract
Today a fast growing interest in microsystems exists both in the academic research world and in commercial industrial products. One reason for this evolution is the sophisticated processing techniques and production methods associated with silicon technology. Silicon micromachining offers the possibility of low-cost highly miniaturized sensors, actuators and systems. However, the planar nature of the photolithography technique used in micromechanics makes it not easy to realize three-dimensional (3-D) structures. Batch and mass fabrication of true 3-D silicon structures is a key step in future micromachining technology that can enrich the world with new 3-D sensors, actuators and systems. Such devices have broad applications from medical, military and household equipment to pure research tools. One category of common 3-D structures used in MEMS is bilayer microstructures, such as micromachined bilayer cantilevers and micromachined bilayer plates. Although this type of 3-D microstructures has been widely integrated in various microsystems, a lot of mechanical behaviors of these microstructures are still unknown. The motivation for this work is to deeply understand the geometric effects on 3-D structures fabricated using bilayer method. The final goal is to implement the new knowledge to obtain better performance of microsystems. This dissertation presents the effect of width on the stress-induced bending of the micromachined bilayer cantilever. Following the foregoing study, a modified method for measuring the residual stress and a novel method for measuring the Poisson’s ratio have been demonstrated. This dissertation also presents the effect of thickness on the stress-induced bending of the micromachined bilayer plate. Following the conclusions, a novel focusing micromirror has been designed and fabricated. Extensive discussion on symmetry has been made to characterize the new bilayer microstructures.