Optical metrology for microsystems inspection

Within recent years the demand for microsystems has increased significantly. Microsystems-technology has been successfully applied, for instance, in areas like telecommunication, automotion, medical technology and sensoring. Accordingly, with the rescaling of dimensions, the requirements concerning the accuracy of surface characteristics, shapes and sizes has grown steadily, resulting just as well in stronger requirements for precise metrological instruments to verify and assure a specified quality level. Since optical metrology is typically not only more flexible and faster than most tactile methods but also easier applicable to the small structures encountered in microsystems-technology, most of these inspection devices are based on optical methods (like for instance classical and confocal microscopy, interferometry, autofocus sensors, triangulation, fringe projection, etc.) or at least include optical methods (like for instance atomic force microscopy, scanning nearfield optical microscopy, or with the fiber optical stylus etc.). Optical methods provide a variety of individual solutions and confusingly many options. To manage the possibilities that optical metrology offers, a profound understanding of this complex technology is inevitable. After a brief general overview of selected metrological systems that are commonly used in microsystems-technology a new method for obtaining 3D microstructures that is subject of a current research project will be discussed in more detail.