| AVS 62nd International Symposium & Exhibition | |
| Helium Ion Microscopy Focus Topic | Thursday Sessions |
| Session HI+AS+NS-ThA |
| Session: | Imaging and Milling with He and Ne Ion Beams |
| Presenter: | Shinichi Ogawa, AIST, Japan |
| Authors: | S. Ogawa, AIST, Japan T. Iijima, AIST, Japan Y. Naitou, AIST, Japan |
| Correspondent: | Click to Email |
The helium ion microscopy is a unique technology for observation of soft materials such as low-k materials and photo resist patterns for LSI fabrication [1] and for nm order etch patterning. Graphene, a two-dimensional sheet of carbon atoms [2], is a promising channel material for next-generation transistors, and we have shown an on-off gating of current through a graphene nano-ribbon which was etched down by the helium ion beam using the helium ion microscope [3] and by controlling electrical properties of the graphene films themselves by the nano-scale helium ion irradiations generating defects [4]. This study precisely shows a nano-scale direct electrical patterning of the graphene film from a point of view of the irradiation conditions.
Helium ion beams of 0.3 nm diameter were 500 X 500 nm2 regions scanned on single-layer graphene films on Si/SiO2 substrates at doses of 0.62 - 10 1016 cm-2 at 30 kV. A spatial resolution of the helium ion microscope patterning on the single-layer graphene was investigated by fabricating nano-ribbons of lines of 100 - 5 nm width. Dynamic force microscopy and scanning capacitance microscopy measurements revealed that helium ionirradiated regions appeared as depressed about 1 nm in topography image at above conditions, while a darker image was acquired at 2.0 1016 cm-2 than those at less dose conditions which means transition to dielectric from metal occurred at the higher dose. A spatial resolution of the helium ion microscope patterning non-monotonically depended on the dosage of the helium ions. Increasing the dose to 5.0 1016 cm-2 improved the spatial resolution to several tens of nanometers. However, doses of more than 1.0 1017 cm-2 degraded the patterning characteristics.
Those results are discussed precisely changing irradiated beam conditions followed by structural analyses by such as CS-TEM.
[1] S. Ogawa, et al., Jpn. J. Appl. Phys., 49 (2010) 04DB12, [2] K. Novoselov, et al., Science 306, 666 (2004), [3] S. Nakaharai, et al., Appl. Phys. Express 5 015101 (2012), [4] S. Nakaharai, et al., 2012 IEEE International Electron Devices Meeting (IEDM), Technical Digest p.72 (2012), [5] Y. Naitou, et al., Appl. Phys. Lett. 106, 033103 (2015)