The importance of surface micromachining processes has increased over the last few years. After the fundamental problems of these technologies have been solved in research institutes, surface micromachined components now arrive in industrial production, e.g. inertial sensors for automotive applications. In comparison to the classical bulk micromachined components, technologies based on surface micromachining provide a wide range of advantages.
Wafer bonding is an basic process in nearly all technologies for industrial MEMS production. To the one wafer bonding is used to pre-process substrates with buried layers, to make special micromachining processes possible. On the other hand wafer bonding is necessary for zero level packaging, the encapsulation and sealing of free moveable structures and cavities on wafer level. The wafer bonding steps of industrial used technologies have to be very reproducible and safer to ensure an economical use by sufficient high yield.