Brugger, Juergen

Guillaumee, Mickael

Martin, Olivier J. F.

Przybylska, Joanna

Santschi, Christian

Vazquez-Mena, Oscar

Infoscience - École polytechnique fédérale de Lausanne

Plasmonic Structures10 years ago, with the article on the extraordinary optical trans-mission through sub-wave-length hole arrays in Nature [8], Ebbesen and his colleagues triggered a tremendous ad-vancement in plasmonic re-search. Due to its suitability to write nanostructures with very high precision, FIB technique provides an ideal tool for the fabrication of plasmonic struc-tures. Noble metals containing periodical structures exhibit surface-plasmon-enhanced transmission of light through subwavelength nanoholes. Such structures have been integrated in the pixels of a commercially available CCD camera with the objective of enhancement of the signal-to-noise ratio (SNR). Fig. 1 shows a schematic illustration of the plasmonic effect on a pixel modified using FIB technique. The optically active part of the CCD has been covered with a 250 nm thick opaque gold layer where periodical slit and groove structures have been engraved. The optically sen-sitive part of the detector is sensitive to ion implantation and, therefore, protected by a Si O 2 deposit located between the active and the gold layer. Impinging ions are absorbed by the protection layer. Fig. 2 displays a SEM image of an individual pixel modified using FIB technique. According to theoretical calculations values on the order of 5 for SNR impro-vement can be expected [9].Nanodispenser (NADIS)Precise deposition of individu-al liquid nanodroplets paves the way for many applications in the fields of bio- and nano-technology. A nanodispenser (NADIS) has been developed Focused Ion Beam: A Versatile Technique for the Fabrication of Nano-DevicesChristian Santsch i 1) , Joanna Przybylsk a 2) , Mickael Guillaumé e 2) , Oscar Vazquez-Men a 3) , Jürgen Brugge r 3) , and Olivier J. F. Marti n 1) Fig. 1. Schematic illustration of the plasmonic effect leading to an enhanced transmission of the slit / groove structures. Surface plasmon polaritons are excited by the incoming light wave and reflected at the periodically arranged corruga-tions resulting in a plasmonic surface waveReceived: September 1th 2008Accepted: Dezember 5th 2008IntroductionNanostructures used in near field optics [1-3] material science [4, 5], and biological applications [6, 7] can easily be realised using Focused Ion Beam (FIB) technique. In this work three applications developed in our laboratories are presented in order to highlight the versatility of FIB technique. Sophisticated nanostructures can be written in a single step into substrates without any need of masks, stamps or other additional means and, most notably, FIB technique enables post-processing of prefabricated devices.Prakt. Metallogr. 46 (2009) x ©  Carl Hanser Verlag, München 1Short CommuniCationx using a standard AFM setup combined with a specially ad-apted cantilever. The principle of NADIS is schematically shown in Fig. 3. A microfluidic channel connecting a liquid reservoir with a nanoaperture is embedded in the NADIS can-tilever. The cantilevers have been produced using standard microfabrication technique, whereas, the nanoaperture, shown in Fig. 3, has been fabri-cated using FIB technique [10]. Square and circular apertures with dimensions down to 80 nm have been drilled into the tip apex of the hollow cantile-ver, which nicely illustrates that FIB technique is, in contrast to standard fabrication methods, not limited to flat surfaces. Prior to the FIB treatment the cantilever tips have been gold coated in order to perform thi-olisation of the perforated tips which ensures a hydrophobic confinement of the liquid in the vicinity of the aperture. As gold is easily removed by FIB mil-ling, the apex of the tips have been protected with a carbon layer prior to the milling ac-tion in order to prevent gold removal due to dispersed ions close to the location where FIB milling takes place. Individual droplets with volumes down to 200 al have been deposited and, moreover, monolayers of PS-P2VP micelles have been locally modified by deposition of glycerol using NADIS tech-nique [11].Stencil lithographyStencil lithography is a shadow mask deposition technique en-abling direct patterning with sub-micron resolution of di-verse substrates, without any need of resist processing. It can be used for local material deposition [12], reactive ion et-ching [13], and ion implantation [14] on prefabricated substra-tes. A schematic illustration of metal deposition using stencil lithography is given in Fig. 4. The whole process includes 3 steps, namely, stencil fixation and alignment, metal depositi-on, and removal of the stencil. Using stencil lithography struc-tures down to a few tens of nm have been realised [12]. Stencil lithography requires the use of nanostructured membranes. The membranes have been fabricated using standard microfabrication techniques, whereas, the nanostructures have subsequently been added using FIB technique. Due to the flexibility of FIB technique individual chips can be post-Fig. 3. Conceptual drawing of the nanodispenser and SEM image of a modified tipFig. 2. SEM images showing top view and cross-section of a modified pixel. The structures have been realised using FIB techniqueFig. 4. The three main steps of stencil lithography: (1) clamp-ing, (2) deposition, and (3) re-lease. Al nanowires have been realised using a stencil contain-ing nanoslits2 Prakt. Metallogr. 46 (2009) xxprocessed and adapted to its specific need. Using this tech-nique slits of widths down to 50 nm have been achieved in a 100 nm thick SiN membrane [15]. A nanostructured memb-rane used for local aluminium deposition and resulting na-nowire are shown figure 4. Na-nostencils can be cleaned and reused. This has successfully been demonstrated for twelve times using stencils shown in the presented example [13]. Furthermore, stencil lithogra-phy is well adapted for patter-ning polymer [13] and nonpla-nar substrates.ConclusionsThe realisation of new ap-plications has successfully been demonstrated by local postprocessing of existing devices. Pixels of a CCD ca-mera and SiN membranes of nanostencils have been mo-dified. Moreover, apexes of 3-dimensional AFM tips have been adapted enabling the re-alisation a nanodispenser. The multiplicity of FIB technique and its importance in the field of nanofabrication has been illustrated on the basis of the presented applications. References [1] Y. Poujet et al., Photo-nics and Nanostructures - Fundamentals and Ap-plications 4, 47 (2006). [2] Y. Poujet et al., Journal of Microscopy 229, 203 (2008). [3] J. Dintinger, S. Klein, T. W. Ebbesen, Advanced Ma-terials 18, 1267 (2006). [4] P. Hoffmann et al., paper presented at the Procee-dings of SPIE - The Inter-national Society for Opti-cal Engineering,  2005. [5] I. Utke et al., Advanced Engineering Materials 7, 323 (2005). [6] C. Danelon, C. Santschi, J. Brugger, H. Vogel, Lang-muir 22, 10711 (2006). [7] J. Jiang, X. M. Li, W. C. Mak, D. Trau, Advanced Materials 20, 1636 (May, 2008). [8] T. W. Ebbesen, H. J. Lezec, H. F. Ghaemi, T. Thio, P. A. Wolff, Nature 391, 667 (Feb, 1998). [9] R. D. R. Bhat, N. C. Panoiu, S. R. J. Brueck, R. M. Os-good, Optics Express 16, 4588 (Mar, 2008). [10] A. Meister, M. Liley, J. Brugger, R. Pugin, H. Heinzelmann, Applied Physics Letters 85, 6260 (2004). [11] A. Meister, S. Krishna-moorthy, C. Hinderling, R. Pugin, H. Heinzelmann, Microelectronic Enginee-ring 83, 1509 (2006). [12] M. M. Deshmukh, D. C. Ralph, M. Thomas, J. Sil-cox, Applied Physics Let-ters 75, 1631 (1999). [13] K. Sidler et al., Microe-lectronic Engineering 85, 1108 (2008). [14] C. Dumas et al., physica status solidi (a) 204, 487 (2007, 2007). [15] O. Vazquez Mena, M. A. F. van den Boogaart, J. Brug-ger, D. o. T. P. In, Transdu-cers: Lyon, France, 2007; pp 195-198., Digest of Technical Papers , Trans-ducers: Lyon, France, 195 (2007).Korrespondenzanschrift: 1)  Nanophotonics and Metrology Laboratory (NAM), STI/IMT/NAM, Station 11, École Polytechnique Fédéral (EPFL), CH-1015 Lausanne, Switzerland 2)  Centre Suisse d’Électronique et de Microtechnique (CSEM), Rue Jaquet-Droz 1, CH 2002 Neuchâtel, Switzerland 3)  Microsystems Laboratory 1 (LMIS1), STI/IMT/LMIS1, Station 17, 1015 École Polytechnique Fédéral (EPFL), CH-1015 Lausanne, SwitzerlandE-Mail: Christian.Santschi@epfl.chPrakt. Metallogr. 46 (2009) xx 3Den Beitrag als PDF finden Sie unter: www.practical-metallography.comPDF of this article: Dokumenten-Nummer: PM 110006Christian SantschiStudy of physics at Swiss Federal Institute of Technology (ETH) Zürich, PhD thesis in the field of chemical physics at ETH Lausanne (EPFL), worked in the domain of nanostructuring at Centre Suisse d’Électronique et Microtechnique (CSEM) prior to the Nanophotonics & Metrology Laboratory at EPFL.4 Prakt. Metallogr. 46 (2009) xx

Focused Ion Beam: A Versatile Technique for the Fabrication of Nano-Devices

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Focused Ion Beam: A Versatile Technique for the Fabrication of Nano-Devices

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