Handbook of Silicon Based MEMS Materials and Technologies

25.5. Formation of Silicon Microstructures

25.5.1. Structure Delineation

Three-dimensional structures in bulk silicon can be formed when the process of PS formation is confined to specified areas of the Si wafers. The most straightforward way of forming spatially confined PS sacrificial layers is to use p-type Si substrates and to confine the process of PS formation laterally by employing photo-lithographically structured masks on the wafer surface. This process is illustrated in Figure 25.14. There, it is also indicated that a wide choice of materials can be used to limit the PS formation process to the desired regions. In principle, any kind of material can be used that can be deposited onto silicon and that can withstand the aggressive chemical ...