Micro-nano electro mechanical systems for practical applications

MEMS (Micro Electro Mechanical Systems) and NEMS (Nano Electro Mechanical Systems) have been developed based on silicon micromachining for practical applications. Sophisticated MEMS device used as a two-axis rotating gyroscope for navigation control system was developed. A silicon ring rotor is electrostatically levitated and rotated at 12,000rpm. The 4mm diameter ring rotor and 5_m radial gap between rotor and electrode were fabricated using deep RIE (Reactive Ion Etching) and the rotor is sandwiched between two glasses which have control electrodes. The levitation is actively controlled by force balancing in all directions using a capacitive displacement sensing and an electrostatic actuation. The rotation is based on the principle of a variable capacitance motor. The function as the high performance gyroscope and accelerometer were successfully demonstrated. Small size relays for high frequency operation are required for LSI tester. MEMS relay which uses a thermal bimetal actuator for making contact to multi-springs was developed. The springs have electrical connections to the backside using electrical feedthrough in a glass, which results in high frequency response up to 20 GHz. Excellent reliability more than 10⁷ cycles was achieved owing to the hermetic sealing performed by wafer level packaging using anodic bonding of glass and silicon. Multiprobe data storage has been developed. High density electrical feedthrough in a glass was used for the interconnection to its control IC. Electrical rewritable recording on a conductive polymer film and a ferroelectric recording were performed. Electron field emitter array for the purpose of multi-column electron beam lithography was developed using carbon nano tube emitter and electrostatic lens for focusing. It was evident that hydrogen covered carbon nano tube reduces the work function for field emission and the emission noise. Highly sensitive sensors using micro-nano structures such as thin cantilevers have been developed. Bow-tie antenna for near field optical microscope and magnetic resonant force microscope will be presented.