ABSTRACT
Micromachining is a process to fabricate the micromechanical parts using silicon. To make a microelectromechanical system (MEMS) device, micromachining is an essential step. There are several positive aspects of silicon micromachining. Micromachining of the silicon substrate is done by selective etching of the substrate to leave behind the desired geometries for the micromechanical structures. Depending on the chemicals used and materials to be etched, wet etching can be divided into two groups: isotropic and anisotropic. Isotropic etching is generally avoided in bulk micromachining as it is not direction dependent. Structures with rounded side walls are produced using this etching. Bulk micromachining creates devices by etching of the wafer and termed as subtractive process, whereas surface micromachining builds devices on top of the wafer, maybe in multilayer, and can be termed as additive process. Surface micromachining is used to fabricate mechanical features such as cantilevers, membranes or free-moving structures on top of a wafer surface.
