Special Section on Nanopatterning

Maskless fabrication of nanogap electrodes by using Ga-focused ion beam etching

[+] Author Affiliations
Takashi Nagase

National Institute of Information and Communications Technology, Kansai Advanced Research Center, 588-2 Iwaoka, Nishi-ku, Kobe 651-2492, Japan

Kenji Gamo

National Institute of Information and Communications Technology, Kansai Advanced Research Center, 588-2 Iwaoka, Nishi-ku, Kobe 651-2492, Japan

Rieko Ueda

National Institute of Information and Communications Technology, Kansai Advanced Research Center, 588-2 Iwaoka, Nishi-ku, Kobe 651-2492, Japan

Tohru Kubota

National Institute of Information and Communications Technology, Kansai Advanced Research Center, 588-2 Iwaoka, Nishi-ku, Kobe 651-2492, Japan

Shinro Mashiko

National Institute of Information and Communications Technology, Kansai Advanced Research Center, 588-2 Iwaoka, Nishi-ku, Kobe 651-2492, Japan

J. Micro/Nanolith. MEMS MOEMS. 5(1), 011006 (February 13, 2006). doi:10.1117/1.2172614
History: Received December 07, 2004; Revised July 25, 2005; Accepted September 01, 2005; Published February 13, 2006
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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 12nm 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 3nm, and the fabrication yield reached 90% for 3to 6-nm-wide gaps. Most of the fabricated nanogap electrodes show high insulating resistance ranging from 1GΩ to 1TΩ.

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© 2006 Society of Photo-Optical Instrumentation Engineers

Citation

Takashi Nagase ; Kenji Gamo ; Rieko Ueda ; Tohru Kubota and Shinro Mashiko
"Maskless fabrication of nanogap electrodes by using Ga-focused ion beam etching", J. Micro/Nanolith. MEMS MOEMS. 5(1), 011006 (February 13, 2006). ; http://dx.doi.org/10.1117/1.2172614


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