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Two- and three-dimensional ultrananocrystalline diamond (UNCD) structures for a high resolution diamond-based MEMS technology

: Auciello, O.; Krauss, A.R.; Gruen, D.M.; Meyer, E.M.; Busmann, H.G.; Tucek, J.; Sumant, A.; Jayatissa, A.; Moldovan, N.; Mancini, D.C.; Gardos, M.N.

Boer, M. de:
Materials science of microelectromechanical systems (MEMS) devices II
Warrendale, PA, United States: Materials Research Society, 2000 (Materials Research Society Symposium Proceedings 605)
ISBN: 1-558-99513-7
ISSN: 0272-9172
Symposium "Materials science of microelectromechanical systems (MEMS) devices" <2, 1999, Boston>
Conference Paper
Fraunhofer IFAM ()

Silicon is currently the most commonly used material for the fabrication of microelectromechanical systems (MEMS). However, silicon-based MEMS will not be suitable for long-endurance devices involving components rotating at high speed, where friction and wear need to be minimized, components such as 2-D cantilevers that may be subjected to very large flexural displacements, where stiction is a problem, or components that will be exposed to corrosive environments. The mechanical, thermal, chemical, and tribological properties of diamond make it an ideal material for the fabrication of long-endurance MEMS components. Cost-effective fabrication of these components could in principle be achieved by coating Si with diamond films and using conventional lithographic patterning methods in conjunction with e.g. sacrificial Ti or SiO2 layers. However, diamond coatings grown by conventional chemical vapor deposition (CVD) methods exhibit a coarse-grained structure that prevents hi gh-resolution patterning, or a fine-grained microstructure with a significant amount of intergranular non-diamond carbon. We demonstrate here the fabrication of 2-D and 3-D phase-pure ultrananocrystalline diamond (UNCD) MEMS components by coating Si with UNCD films, coupled with lithographic patterning methods involving sacrificial release layers. UNCD films are grown by microwave plasma VCD using C60-Ar or CH4-Ar gas mixtures, which result in films that have 3-5 nm grain size, are 10-20 times smoother than conventionally grown diamond films, are extremely resistant to corrosive environments, and are predicted to have a brittle fracture strength similar to that of single crystal diamond.