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Journal of Micro/Nanolithography, MEMS, and MOEMS

Maskless fabrication of nanogap electrodes by using Ga-focused ion beam etching
Author(s): Takashi Nagase; Kenji Gamo; Rieko Ueda; Tohru Kubota; Shinro Mashiko
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Paper Abstract

We develop maskless fabrication methods using sputter etching with Ga-focused ion beams (FIBs) to obtain nanogap electrodes with high reproducibility. This method is based on in situ monitoring of etching steps by measuring current through patterned electrode films. The etching steps are terminated electrically at a predetermined current level. In the present experiment, 30-keV Ga FIBs with beam size of ~12 nm is irradiated, and the effect of film structures and monitoring current is investigated to obtain reliable fabrication methods. We find that electrode gaps much narrower than the beam size can be reproducibly fabricated. The controllability of the fabrication steps is significantly improved by using triple-layered films consisting of a thin Ti top, an Au electrode, and a bottom Ti adhesion layer. The minimum gap width achieved is ~3 nm, and the fabrication yield reached ~90% for ~3- to 6-nm-wide gaps. Most of the fabricated nanogap electrodes show high insulating resistance ranging from 1 GΩ to 1 TΩ.

Paper Details

Date Published: 1 January 2006
PDF: 6 pages
J. Micro/Nanolith. 5(1) 011006 doi: 10.1117/1.2172614
Published in: Journal of Micro/Nanolithography, MEMS, and MOEMS Volume 5, Issue 1
Show Author Affiliations
Takashi Nagase, National Institute of Information and Communications Technology (Japan)
Kenji Gamo, Osaka Univ. (Japan)
Rieko Ueda, National Institute of Information and Communications Technology (Japan)
Tohru Kubota, National Institute of Information and Communications Technology (Japan)
Shinro Mashiko, National Institute of Information and Communications Technology (Japan)


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