RF NEMS and applications
II-7: RF NEMS and Applications |
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Dr. Ma Jian-Guo, |
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Abstract |
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Because of the advances of semiconductor manufacturing technologies, the scale of electromachanic system (EMS) shrinks from micro-scale (MEMS) to nano-scale (NEMS). Basically, EMS have three types of applications: EMS element can simply deflect under the applied force (mechanical, electronic, etc), EMS device amplitudes of oscillation can change, or EMS process can be used to fabricate some parts of electronic circuits. MEMS has demonstrated its powerfulness and promising applications in the three areas such as MEMS-based sensors, MEMS-based biochips, RF MEMS etc.
NEMS devices promise to revolutionize measurements of extremely small displacements and extremely weak forces, particularly at the molecular scale. Indeed with surface and bulk NEMS techniques, NEMS can now be built with masses approaching a few attograms (10-18 g) and with cross-sections of about 10 nm. Resonators with fundamental frequencies above 10 GHz (1010 Hz) can now be built using NEMS processes involving state-of-the-art nanolithography at the 10 nm scale. These techniques apply to bulk silicon, epitaxial silicon and silicon-on-insulator heterostructures, as well as to systems based on gallium arsenide and indium arsenide. A second important attribute of NEMS is that they dissipate very little energy, a feature that is characterized by the high quality or Q factor of resonance. As a result, NEMS are extremely sensitive to external mechanisms. High Q values are therefore an important attribute for both resonant and deflection sensors as well as RF circuit applications. That forms the fundamental of RF NEMS and applications. Conventional approaches thus appear to hold little promise for high-efficiency transduction with the smallest of NEMS devices. Therefore, one can not just simply follow the MEMS approaches for NEMS, especially for RF NEMS due to the small size and high-frequency. Nonetheless, we have a host of intriguing new concepts in the pipeline. One of the most stylish materials resulting from nanotechnology is the stable phase of carbon known as carbon nanotubes. However, most efforts now under-going in the literature are in the materials and the processes how to make them. |
