Nanocomposite thin film for bioMEMS applications
II-3: Nanocomposite Thin Films for bioMEMS applications |
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Sam Zhang and Hejun Du |
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Abstract |
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Diamond-like carbon, or amorphous carbon, is biocompatible, has very low surface roughness and good mechanical properties, and thus have big potential to be used in microdevices in medical applications. However, high residual stresses proved to be the major challenge for any practical usage. This project is to develop a stress-free film for use in BioMEMS (biological microelectromechanical systems) devices.
Nanocompoiste films of nc-SiC/a-C or nanocrystalline silicon carbide embedded in amorphous carbon (diamond-like carbon) matrix is identified as a very promising candidate. Magnetron sputtering is used to deposit the films, and thermal annealing is performed to induce nc-SiC formation. X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy are carried out to determine the bonding characteristics in the amorphous material. The intrinsic stress and hardness are determined by wafer curvature measurement and nanoindentation respectively. X-ray Diffractometry is used to study the SiC nanocrystals. The initial results show a reduction in the as-deposited stress and increase in thermal stability. Micro-fabrication of cantilevers has been demonstrated using both wet and dry etching methods. Studies will be carried out on understanding of the bonding characteristics, surface energy, stress-relieve mechanisms, effect of nanocrystal and nanostructured surface on mechanical and biological properties, compatibility of the nanocomposite film with the current MEMS micromachining techniques. Low-stress or no-stress films or coatings have extensive applications in microfluidic channels, nanoporous membrane for immunoisolation, and other bioMEMS fields. |
