Possible Applications of Freestanding Carbon Nanotubes in MEMS Technology

Carbon nanotubes (CNTs) are molecular-scale tubes of graphitic carbon with outstanding properties. They are among the stiffest and strongest fibers known, and have remarkable electronic properties and many other unique characteristics. In our experiment, CNTs were synthesized using plasma enhanced chemical vapor deposition on the silicon wafer with patterned iron catalytic layer. If the catalyst is only located in certain areas (patterned), then nanotubes grow only in those areas. The arrays with freestanding carbon nanotubes were created. It is possible to apply this method of CNTs preparation in many areas, such as sensor-based applications. For example, thanks to the CNTs dimensions is possible to increase the surface in capacitance pressure sensors that are one of the most using in microelectronic devices for pressure sensing. The novel MEMS structure was designed to be utilized as capacitance pressure sensor. The most applicable topology of the MEMS structure was chosen by means of electrostatic models analysis. There were proposed five structures and the best solution was selected the chessboard structure, since it provides the suitable capacity for the sensor. The computing model supposes geometric symmetry of created CNTs arrays, thanks to that it was necessary to find only two dimensions (width of CNTs array and gap between those arrays). The very first laboratory results measured on fabricated structures show very accurate values which correspond with simulated results.