Micro Electro-Mechanical Systems
Micro Electro-Mechanical Systems (MEMS) is the integration of mechanical elements, sensors, actuators and electronics on a common silicon substrate using microfabrication techniques. MEMS are a hot area of research because they integrate sensing, analyzing and responding on the same silicon substrate hence promising realization of complete systems-on-a-chip. As MEMS are manufactured using batch fabrication techniques similar to IC technology, MEMS are expected to deliver high functionality at low prices.
Current systems are limited by the capability of sensors and actuators, as these are bulkier and less reliable than the microelectronic circuit. In a MEM system the sensors act as the eyes' and gather 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 modify the environment suitably. The electronics on the MEMS are manufactured using IC techniques while micro machining techniques are used to produce the mechanical and electromechanical parts. MEMS Fabrication:
There are number of methods to fabricate MEMS like silicon surface micromachining, silicon bulk machining, electro discharge machining, LIGA (in German, Lithographie, Galvanoformung(Electro Plating), Abformung(Injection Moulding)) .Only silicon surface micromachining is discussed here.
Silicon Surface Micromachining
Silicon surface micromachining uses the same equipment and processes as the electronics semiconductor industry. There are three basic building blocks in this technology, which are the ability to deposit thin films of material on a substrate, to apply a patterned mask on top of the films by photolithographic imaging, and to etch the films selectively to the mask. A MEMS process is usually a structured sequence of these operations to form actual devices.
1. Deposition Processes: One of the basic building blocks in MEMS...
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