Fabrication of MEMS Components Based on Ultrananocrystalline Diamond Thin Films and Characterization of Mechanical Properties

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 high- resolution 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 andin-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.