A novel self-sensitive SFM for nondestructive measurement of tiny vertical surfaces with restricted access

This paper presents a novel scanning force microscope (SFM) for the nondestructive measurement of tiny micromachined vertical surfaces, which conventional SFMs or other instruments cannot access without destruction. In addition to its access flexibility, our SFM uses the self-sensitive cantilever for sensing its own deflections. As a result, it can access tiny areas and restricted locations for measuring the features of microstructures; for example, the surfaces of a tiny vertical reflecting mirror, the inside walls of a small hole and the inner surfaces of a micro mold insert. The SFM has been successfully used in evaluating the vertical reflecting surfaces of silicon mirrors, the side walls of cavities in a micro mold and the vertical reflecting surfaces of embossed polymer mirrors with a dimension of 500 μm long x 100 μm wide x 200 μm deep (high). In this paper, details of the design and instrumentation of our SFM, and how it is used for monitoring the process for fabricating a polymer-based optical switch will be presented.