Meguro-ku, Japan
Meguro-ku, Japan

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Nishimori Y.,University of Shizuoka | Nishimori Y.,Project 3D Center | Ueki S.,Omron Corporation | Ueki S.,Project 3D Center | And 9 more authors.
Journal of Vacuum Science and Technology B:Nanotechnology and Microelectronics | Year: 2013

As an effective application of neutral beam etching (NBE) to microelectromechanical systems (MEMS), here we propose a combination of conventional plasma processes and NBE to remove plasma-induced damage. To evaluate the effect of the combined approach quantitatively, we measured the resonance properties of a microcantilever before and after NBE treatment and compared them with a characteristic quantity. The thickness of the damage layer times the imaginary part of the complex Youngs modulus (δEds), which is a parameter of surface damage. Although a plasma process makes the damaged surface of the microcantilevers during their fabrication, the removal of that damage by NBE is confirmed as a reduction in δEds. NBE can provide a damage-free surface for MEMS devices without a high-temperature annealing process. © 2013 American Vacuum Society.

Ueki S.,Project 3D Center | Ueki S.,Project vice Center | Ueki S.,Omron Corporation | Nishimori Y.,Project vice Center | And 11 more authors.
Japanese Journal of Applied Physics | Year: 2011

We propose a method to evaluate the effect of process damage on microcantilever surfaces, introduced by processes such as plasma etching, on their mechanical properties. Using this method, we can compare the mechanical properties before and after etching even if the process changes the microcantilever thickness. Defects at the microcantilever surface affect the quality (Q) factor of the microcantilever, but the Q factor cannot be used as an indicator to evaluate process damage because it also depends on the microcantilever thickness. On the basis of theoretical considerations, we propose using Q=f (f : resonance frequency) as an indicator because both Q and f are proportional to the thickness for very thin microcantilevers. We verified our method experimentally by etching microcantilever surfaces using conventional plasma etching and neutral beam etching, which can etch silicon without damage. As a result, the Q=f value markedly decreased after plasma etching but stayed nearly the same after neutral beam etching. © 2011 The Japan Society of Applied Physics.

Ueki S.,Project 3D Center | Ueki S.,Omron Corporation | Nishimori Y.,University of Shizuoka | Imamoto H.,Omron Corporation | And 8 more authors.
IEEJ Transactions on Sensors and Micromachines | Year: 2010

We have analyzed the effect of penetration of the electric fieldinto the semiconductor on the electrical and mechanical characteristics of comb-drive actuators. In this study we found two specific effects due to the depletion layer: (1) the electro-mechanical conversion factor is a function of the depletion layer and becomes smaller than that for the "ideal conductor" assumption, and (2) an additional stiffness appears in the mechanical system. Following the change in the electro-mechanical conversion factor, the resonance peak becomes lower than that of an ideal conductor. These effects are relatively small when the gap between the comb-fingers and the substrate is of the order of a micrometer. However if the gap is 0.1 μm, the electromechanical conversion factor decreases by about 2.8%. In this analysis, we have taken only the depletion effect into account; howeverfor a more complete analysis we should also consider the surface traps induced by unpassivated surface bonds. © 2010 The Institute ofElectrical Engineers of Japan.

Chikamoto T.,Project 3D Center | Shimada Y.,Project 3D Center | Umetsu M.,Tohoku University | Sugiyama M.,University of Tokyo
Proceedings of the IEEE International Conference on Micro Electro Mechanical Systems (MEMS) | Year: 2013

We report on the assembly process for single-walled carbon nanotubes (SW-CNTs) bundle on the tip of cantilever for atomic force microscopy (AFM) by dielectrophoresis (DEP). In DEP process, an ac electric field (20 V p-p, 5 MHz) was applied between a tungsten probe and the cantilever tip to form the SW-CNTs bundle bridge. We can monitor the SW-CNTs bridging process in real time under an optical microscope and successfully assembled SW-CNTs bundle with a diameter of approximately 100 nm on the tip. To compare the performance of our fablicated CNT cantilever with conventional cantilevers, we scanned a porous aluminum surface using AFM. From AFM measurements, we confirmed that our cantilever by DEP allowed us to obtain high resolution images similarly to conventional cantilevers with strong mechanical strength and good stability of scanning. © 2013 IEEE.

Wakioka H.,Project 3D Center | Yamamoto S.,Fujikura Ltd | Tabata K.V.,University of Tokyo | Tabata K.V.,Japan Science and Technology Agency | And 2 more authors.
Proceedings of the IEEE International Conference on Micro Electro Mechanical Systems (MEMS) | Year: 2013

This paper reports a droplet formation device having nanochannels fabricated with femtosecond-laser-assisted etching. With the combination of nanochannels embedded in a substrate and microchannels on the substrate surface, approximately 650 nm diameter water phase liquid droplets (approximately 150 aL in volume) have been produced. In addition, we confirmed that enzyme reaction inside a femtoliter or attoliter droplet was digitally observed by fluorescence for the first time. Such droplets can be used for single-molecule enzymology instead of conventional arrays of femtoliter chambers [1]. © 2013 IEEE.

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