What is MEMS/Microsystems?

MEMS-based pressure sensors

Microelectromechanical systems (MEMS) is the technology of very small devices. MEMS are also referred to as micromachines in Japan, or micro systems technology (MST) in Europe.

MEMS are made up of components between 1 to 100 micrometres in size (i.e. 0.001 to 0.1 mm), and MEMS devices generally range in size from 20 micrometres to a millimetre (i.e. 0.02 to 1.0 mm). At these size scales, the standard constructs of classical physics are not always useful. Because of the large surface area to volume ratio of MEMS, surface effects such as electrostatics and wetting dominate over volume effects such as inertia or thermal mass. The potential of very small machines was appreciated before the technology existed that could make them (see, for example, Richard Feynman's famous 1959 lecture There's Plenty of Room at the Bottom). MEMS became practical once they could be fabricated using modified semiconductor device fabricationtechnologies, normally used to make electronics. These include molding and plating, wet etching (KOH,TMAH) and dry etching (RIE and DRIE), electro discharge machining (EDM), and other technologies capable of manufacturing small devices. An early example of a MEMS device is the resonistor – an electromechanical monolithic resonator.

In the cleanroom

This type of research requires access to advanced equipment, processes and clean-room facilities of the same type as used for the fabrication of microelectronics. The MST research group fabricates their polymer structures at the MST Polymer lab on KTH campus, and their silicon structures at KTH Semiconductor Laboratory (ELAB) located in Kista, 12 km outside of Stockholm, which comprises of 1000 square meters of clean-room area ranging from class 100 to class 10, 000.

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