Handbook of Silicon Based MEMS Materials and Technologies

28.4. SOI-Wafer-Based Surface Micromachining

28.4.1. Benefits of SOI Wafers for Surface Micromachining

In addition to the sacrificial layer based surface micromachining technologies introduced so far, which use polycrystalline silicon, silicon germanium, or metals as mechanical active layers, SOI-wafer-based surface micromachining technologies are now state-of-the-art and commercially available as MEMS foundry technologies, as offered, for example, by X-FAB Semiconductor Foundries [32]. This special substrate provides many technological benefits, despite being cost intensive. However, the main advantage is that the moveable structures are made from a single crystalline device layer of 15 μm, and hence have excellent, well-defined mechanical ...