Microelectromechanical SystemsMicroelectromechanical systems (MEMS) are the integration of mechanical elements, sensors, actuators, and electronics on a common silicon substrate using microfabrication techniques. MEMS represent a very interesting area of ​​research because they integrate sensing, analysis and response on the same silicon substrate, thus promising the realization of complete systems on chips. Since MEMS are produced using batch manufacturing techniques similar to IC technology, MEMS are expected to provide high functionality at low prices. Current systems are limited by the capacity of sensors and actuators, as they are bulkier and less reliable than microelectronic circuitry. In a MEM system, sensors act as "eyes" and collect data about the environment. The microelectronic circuit, which is the "brain", processes the data and accordingly controls the mechanical systems, the "arms" of the MEMS, to appropriately modify the environment. The electronics on MEMS are manufactured using IC techniques while micromachining techniques are used to produce the mechanical and electromechanical parts.MEMS Fabrication: There are numerous methods to fabricate MEMS such as micromachining of the silicon surface, bulk machining of silicon, electric discharge processing, LIGA (in German, Lithographie, Galvanoformung (electroplating), Abformung (injection molding)). Only micromachining of the silicon surface is discussed here. Silicon Surface MicromachiningSilicon surface micromachining uses the same equipment and processes as the electronic semiconductor industry. There are three key elements to this technology, namely the ability to deposit thin films of material onto a substrate, to apply a patterned mask on top of the films using photolithographic imaging, and to selectively etch the films onto the mask. A MEMS process is usually a structured sequence of these operations to form actual devices.1. Deposition processes: One of the fundamental elements of MEMS processing is the ability to deposit thin films of material. This is achieved through processes such as PVD or CVD.2. Lithography: Lithography in the MEMS context is typically the transfer of a pattern onto a photosensitive material by selective exposure to a radiation source such as light. In micromachining lithography, the photosensitive material used is typically a photoresist. When the resist is exposed to a radiation source of a specific wavelength, the chemical resistance of the resist to the developing solution changes.3. Etching: If the resist is placed in a developing solution after selective exposure to a light source, it will etch away one of two regions (exposed or unexposed). Then another layer of material is deposited and the first layer is selectively removed with an etch as shown in the figure, obtaining the required MEMS.