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Nishi-Tokyo-shi, Japan

Tomizawa Y.,3nter
Nihon Kikai Gakkai Ronbunshu, C Hen/Transactions of the Japan Society of Mechanical Engineers, Part C | Year: 2012

In order to bring the nano processing technology using SPM (scanning probe microscope) probes from R&D stage to practical use, it is indispensable to improve its throughput drastically. One way to achieve higher throughput is fabricating an array of multiple probes and using these probes simultaneously. In this case, deviation of electric contact characteristics among probe tips may disturb the optimal processing action. In this study, the authors are focusing on the relation between the contact resistance and the contact force of nanoscale probe tips. We used an AFM (atomic force microscope) which can apply a bias voltage to a substrate holder and measured the contact resistance between an AFM probe tip coated with a conductive film and a surface of conductive substrates. The substrate surface condition should resemble the practical use. Therefore, we employed a cleaning process feasible in the actual manufacturing environment. By investigating the effects of the several factors such as the surface condition of substrates, the tip radius of probes, the authors studied the quantitative deviation and dispersion of the actual contact characteristics from the traditional contact theory. © 2012 The Japan Society of Mechanical Engineers.

Kubota T.,Tohoku University | Kubota T.,3nter | Watanabe N.,Mizuho Information and Research Institute | Ohtsuka S.,Mizuho Information and Research Institute | And 5 more authors.
Journal of Physics D: Applied Physics | Year: 2012

We investigated the neutralization mechanism of ions created by collisions with a graphite surface by numerical simulations using an efficient and stable simulator developed by us based on time-dependent density functional theory (TD-DFT) to clarify the mechanism responsible for generating neutral beams in a highly efficient neutral beam source developed by Samukawa et al (2001 Japan. J. Appl. Phys. 40 L779). The results from the simulations revealed that negative ions (Cl -) have higher neutralization efficiency than positive ions C1 + 2, which was consistent with previous experimental results. The origin of this difference was investigated in terms of the energy alignment between electronic states participating in the charge transfer process. We found that the electronic states of Cl - have similar energies with those of graphite, while those of C1 + 2 and graphite have large differences in energies. This could be interpreted as resonant charge transfer occurring in the neutralization process of negative ions, while Auger charge transfer is dominant in that of positive ions. This interpretation was also strengthened by results where electron transfer probability to the excited states was much larger for collisions of graphite with C1 + 2 than with Cl -. This suggested that the different mechanisms are the reason for the difference in neutralization efficiency between negative and positive ions. © 2012 IOP Publishing Ltd.

Kubota T.,Tohoku University | Kubota T.,3nter | Watanabe N.,Mizuho Information and Research Institute | Ohtsuka S.,Mizuho Information and Research Institute | And 5 more authors.
Journal of Physics D: Applied Physics | Year: 2014

The charge transfer process between chlorine particles (ions or neutrals) and a graphite surface on collision was investigated by using a highly stable numerical simulator based on time-dependent density functional theory to understand the generation mechanism of a high-efficiency neutral beam developed by Samukawa et al (2001 Japan. J. Appl. Phys. 40 L779). A straightforward calculation was achieved by adopting a large enough unit cell. The dependence of the neutralization efficiency on the incident energy of the particle was investigated, and the trend of the experimental result was reproduced. It was also found that doping the electrons and holes into graphite could change the charge transfer process and neutralization probability. This result suggests that it is possible to develop a neutral beam source that has high neutralization efficiency for both positive and negative ions. © 2014 IOP Publishing Ltd.

Abasaki M.,3nter | Abasaki M.,Fuji Electric Co. | Souma S.,Fuji Electric Co. | Takeda M.,3nter | And 4 more authors.
Proceedings of the IEEE International Conference on Micro Electro Mechanical Systems (MEMS) | Year: 2011

Self-assembly of colloidal particles has an advantage of low cost, high productivity and applicability to various devices. The capability of assembling nano-scale particles on three dimensional structures can extend the fields of application, such as high-sensitivity gas sensors and bioassay devices with surface-functionalized particles. We demonstrate such assembly where monolayer polystyrene particles were assembled only on the sidewall of trenches etched on a silicon wafer. Moreover, it was found that the assembly structure can be controlled by the scallops when its periodicity is nearly the same as the particle diameter.

Tomizawa Y.,3nter | Tomizawa Y.,Toshiba Corporation | Ando Y.,3nter | Ando Y.,Tokyo University of Agriculture and Technology | And 2 more authors.
Journal of Advanced Mechanical Design, Systems and Manufacturing | Year: 2013

Precise processes or devices utilizing scanning nanoprobes, e.g., probe-based nanolithography and probe-based data storage, are state-of-the-art technologies that can handle nm-sized tiny patterns. To transfer these technologies from the research and development stage to practical implementation, a significant improvement in the wear resistance of the probe tip is required for reliable and long-term operation of the system. On the other hand, to remove the unevenness of the size of drawn patterns or recorded bits, the electric contact resistance at the nanoscale sliding contact area of the probe tip must be stable even when the scanning speed of the probe increases to achieve higher throughput. To solve these dilemmatic problems, tribological investigation of the probe tip is very important. In this study, the influence of the material properties on the relations among electric contact resistance, friction force, and wear durability of nanoprobe tips was examined in detail to clarify the tribological phenomena that occur at the nanoscale contact area of the probe tips. From the results, the authors discussed the key material properties that are dominant for the abovementioned three tribological factors. In conclusion, management of the surface oxide thickness of metal electrodes was the key among all the three factors. Copyright © 2013 by JSME.

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