Ultrananocrystalline diamond thin films for MEMS and moving mechanical assembly devices.
MEMS devices are currently fabricated primarily in silicon because of the available surface machining technology. A major problem with the Si-based MEMS technology is that Si has poor mechanical and tribological properties [J.J. Sniegowski, in: B. Bushan (Ed.), Tribology Issues and Opportunities in MEMS, Kluwer Academic Publisher, The Netherlands, 1998, p. 325; A.P. Lee, A.P. Pisano, M.G. Lim, Mater. Res. Soc. Symp. Proc. 276 (1992) 67.], and practical MEMS devices are currently limited primarily to applications involving only bending and flexural motion, such as cantilever accelerometers and vibration sensors. However, because of the poor flexural strength and fracture toughness of Si, and the tendency of Si to adhere to hydrophilic surfaces, even these simple devices have limited dynamic range. Future MEMS applications that involve significant rolling or sliding contact will require the use of new materials with significantly improved mechanical and tribological properties, and the ability to perform well in harsh environments, Diamond is a superhard material of high mechanical strength, exceptional chemical inertness, and outstanding thermal stability. The brittle fracture strength is 23 times that of Si, and the projected wear life of diamond MEMS moving mechanical assemblies (MEMS MMAs) is 10 000 times greater than that of Si MMAs. However, as the hardest known material, diamond is notoriously difficult to fabricate. Conventional CVD thin film deposition methods offer an approach to the fabrication of ultra-small diamond structures, but the films have large grain size, high internal stress, poor intergranular adhesion, and very rough surfaces, and are consequently ill-suited for MEMS MMA applications. Diamond-like films are also being investigated for application to MEMS devices. However, they involve mainly physical vapor deposition methods that are not suitable for good conformal deposition on high aspect ratio features, and generally they do not exhibit the outstanding mechanical properties of diamond. We demonstrate here the application of a novel microwave plasma technique using a unique C{sub 60}/Ar or CH{sub 4}/Ar chemistry that produces phase-pure ultrananocrystalline diamond (UNCD) coatings with morphological and mechanical properties that are ideally suited for MEMS applications in general, and MMA use in particular. We have developed lithographic techniques for the fabrication of UNCD-MEMS components, including cantilevers and multi-level devices, acting as precursors to microbearings and gears, making UNCD a promising material for the development of high performance MEMS devices.
- Research Organization:
- Argonne National Lab. (ANL), Argonne, IL (United States)
- Sponsoring Organization:
- USDOE Office of Science (SC); EE
- DOE Contract Number:
- DE-AC02-06CH11357
- OSTI ID:
- 943255
- Report Number(s):
- ANL/CHM/JA-38646; TRN: US200916%%682
- Journal Information:
- Diamond Related Mater., Vol. 10, Issue 11 ; Nov. 2001; ISSN 0925-9635
- Country of Publication:
- United States
- Language:
- ENGLISH
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Related Subjects
47 OTHER INSTRUMENTATION
ACCELEROMETERS
ADHESION
ASPECT RATIO
BENDING
CHEMISTRY
COATINGS
DEPOSITION
DIAMONDS
DYNAMICS
EQUIPMENT
FABRICATION
FILMS
FLEXURAL STRENGTH
FRACTURE PROPERTIES
GEARS
GRAIN SIZE
MACHINING
MATERIALS
MECHANICAL PROPERTIES
MOTION
NETHERLANDS
PERFORMANCE
PHYSICAL VAPOR DEPOSITION
PLASMA
RANGE
ROLLING
SILICON
STABILITY
SURFACES
THIN FILMS
TRIBOLOGY
WEAR
WELLS