Microelectromechanical Systems Glossary

Microelectromechanical Systems Glossary
CMP: Chemical mechanical planarization: The use of a compound to polish a wafer's surface to eliminate topological layer effects in the manufacturing of semiconductors and MEMS

CVD: Chemical vapor deposition is a means of laying down material on the top of a wafer.

Darpa: Defense Advanced Research Projects Agency. Darpa has been a significant supporter of MEMS research in the United States throughout the 1990s and up to the present time.
www.darpa.mil/mto/

EDP: Ethylene diamine pyrocatechol, a silicon etchant like KOH or TMAH, but highly toxic.

HARM: High aspect ratio micromachining.

Hydrofluoric Acid (HF): An acid (in various dilutions) commonly used to etch oxide in many MEMS fabrication processes, such as the sacrificial oxide release process.

KOH: Potassium hydroxide. An isotropic etchant that attacks silicon at different rates in different directions.

Liga: Lithographie, galvanoformung und abformung, the German words for Lithography, Electroplating and Molding. Liga is a type of HARM suitable for making parts with depths significantly greater than lateral dimensions from metals, metal alloys, plastics or ceramics. The Liga process uses synchrotron radiation to create a pattern in an X-ray resist, usually PMMA. The use of synchrotron radiation allows lateral feature sizes that are as small as a few microns in dimension, and straight, smooth vertical side walls that can be as tall as several millimeters. Once the PMMA is exposed, it is chemically developed and used as a mold for electroforming metal or metal alloys.

MCNC: Microelectronics Center of North Carolina; developer of the MUMPs process.

MEMS: Microelectromechanical systems.

MOEMS: micro-optical electro-mechanical systems, also known as optical MEMS and generally taken to include waveguides, diffraction gratings, moving mirror and moving bubble devices.

MUMPs: The Multi-user MEMS Process developed by MCNC and funded by Darpa; a process used for three-layer polysilicon surface micromachining prototyping.

MST: Microsystems technology.

Nexus: Network of Excellence in Multifunctional Microsystems. Established in 1992 with European Union funding, Nexus is now a non-profit association headquartered in Grenoble, France, with the aim of providing access to information and guidance on MEMS/Microsystems.
www.nexus-emsto.com

PMMA: Polymethylmethacrylate resist commonly used in MEMS characterization.

RIE: Reactive ion etch: A dry- etch technique capable of making silicon structures with high aspect ratios.

SOI: Silicon on insulator. Wafer type that includes a buried electrical insulator layer just below the surface. This layer is conventionally silicon dioxide. Such wafers can make a convenient starting point for some types of MEMS.

Summit: Sandia Ultra-planar, Multilevel MEMS Technology; comes in both four- and five-layer versions.

TMAH: Tetramethylammonium hydroxide: an anisotropic wet etchant.