Fabrication of MEMS Components Based on Ultrananocrystalline Diamond Thin Films and Characterization of Mechanical Prope
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Fabrication of MEMS Components Based on Ultrananocrystalline Diamond Thin Films and Characterization of Mechanical Properties* A. V. Sumant1 O. Auciello1, A. R. Krauss1, D. M. Gruen1, D. Ersoy2, J. Tucek1, A. Jayatissa1, E. Stach3, N. Moldovan4, D. Mancini4, H. G. Busmann5, E. M. Meyer6 1
Materials Science Division, Argonne National Laboratory, Argonne, IL. University of Illinois-Chicago, IL. 3 National Center for Electron Microscopy, Lawrence Berkeley Laboratory, Berkeley, CA. 4 Experimental Facility Division, Argonne National Laboratory, Argonne, IL. 5 Fraunhofer Institute for Applied Materials Science, Bremen, Germany. 6 Institute for Microsensors, Actuators, and Systems, University of Bremen, Germany. 2
ABSTRACT The mechanical, thermal, chemical, and tribological properties of diamond make it an ideal material for the fabrication of MEMS components. However, conventional CVD diamond deposition methods result in either a coarse-grained pure diamond structure that prevents highresolution patterning, or in a fine-grained diamond film with a significant amount of intergranular non-diamond carbon. At Argonne National Laboratory, we are able to produce phase-pure ultrananocrystalline diamond (UNCD) films for the fabrication of MEMS components. UNCD is grown by microwave plasma CVD using C60-Ar or CH4-Ar plasmas, resulting in films that have 3-5 nm grain size, are 10-20 times smoother than conventionally grown diamond films, and can have mechanical properties similar to that of single crystal diamond. We used lithographic patterning, lift-off, and etching, in conjunction with the capability for growing UNCD on SiO2 to fabricate 2-D and 3-D UNCD-MEMS structures. We have performed initial characterization of mechanical properties by using nanoindentation and in-situ TEM indentor techniques. The values of Hardness (~88 GPa) and Young's modulus (~ 864 GPa) measured are very close to those of single crystal diamond (100 GPa and 1000 GPa respectively). The results show that UNCD is a promising material for future high performance MEMS devices.
INTRODUCTION Over the past few years, there has been considerable progress in the area of MEMS technology. Most of the research in this area is centered around finding suitable material with superior physical, chemical and mechanical properties [1-4] and this basically stems from the ever increasing demands on the operating limits of MEMS devices. Diamond, because of its outstanding physical, chemical and mechanical properties is being considered as a possible substitute material over conventional silicon. Therefore, various groups are exploring diamond coatings to produce MEMS devices capable of performing useful work. A large number of MEMS structures have been reported [5-9], using conventional CH4/(98-99%) H2 plasma chemistry [10] to grow diamond films EE5.33.1
by chemical vapor deposition (CVD) on Si and SiO2 patterned structures. However, fabricating MEMS components out of diamond at length scales relevant to MEMS applications is still a challenging task because the current
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