Advanced Surfactant-Modified Wet Anisotropic Etching

In the area of Micro Electro Mechanical Systems (MEMS), bulk micromachining and surface micromachining are two main technologies. Bulk micromachining defines structures by selectively etching inside a substrate while surface micromachining uses a succession of thin film deposition and selective etching on top of a substrate. The two technologies are quite different, resulting in different dimensions and different mechanical properties. Although bulk micromachining is usually considered to be the older technology, the two developments run parallel. This is due to the fact that the two different approaches have trade-offs. Taking an example of MEMS capacitance accelerometers, surface micromachined structures use smaller chip area, thus leaving more space for the electronics. On the other hand, in bulk micromachining the larger mass gives greater sensitivity for accelerometers and the larger area leads to larger capacitances for easy read out, which are extremely useful in the inertial device fabrication.