Fountain Pen Nanolithography (FPN)

Draw Chemical Structures On A Variety of Surfaces With A Fountain Pen Variety of Inks With Complete Structural & Chemical Characterization of the Drawing Process with Transparent AFM/Raman & NanoLithography Fluorescence Spectral Imaging for On -line Structural & Chemical Mapping NanoLithography of Liquids & Gases Transparent On-line Optical Viewing of the NanoDrawing Process Full Spectroscopic Characterization of the Drawing Process AFM Map of Single Gold Nanopartic les of 1.4 nm Height Deposited With FPN (Top) & Raman Map of The G+ Mode of Carbon Nanotubes Drawn As A Complex Structure (Bottom) The Next Evolution In Near-field NanoCharacterizationTM fountain pen nanochemistry The evolution of fountain pen nanolithography: Controlled multiprobe delivery of liquids and gases Talia Yeshua,1,2 Shalom Weinberger,1,2 Hesham Taha,6 Aaron Lewis,1,2 Michael Layani2,3 Shlomo Magdassi,2,3 Christian Lehmann,4 Stephanie Reich,4 Chaim Sukenik,5 Sophia Kokotov6 and Rimma Dekhter6 1. Department of Applied Physics, Selim and Rachel Benin School of Engineering and Computer Science & 2. The Krueger Center for Nanoscience and Nanotechnology, & 3. The Institute of Chemistry, Casali Center for Applied Chemistry, The Hebrew University of Jerusalem, Edmond Safra Campus, Givat Ram, Jerusalem, Israel. 4. Department of Physics, Freie Universität Berlin, Berlin, Germany. 5. The Jerusalem College of Technology, Jerusalem, Israel. 6. Nanonics Imaging Ltd, Jerusalem, Israel FIGURE 1 Introduction Schematics The field of ambient chemical of multiprobe nanolithography technologies was born fountain pen in 1999 with two papers. One paper was nanolithography system. (a) based on the dip pen concept where to Cantilevered glass achieve the smallest writing dimensions probes with AFM a dry molecular ink was coated on an sensitivity allow atomic force microscopy-like probe for a complete [1]. This method was called dip pen view of the probe tip which permits nanolithography (DPN). A second a direct view paper was based on the concept of a of the writing fountain pen [2] and fully employed with a standard atomic force microscopy (AFM) and upright optical its feedback mechanisms but the microscope. writing element used was a nanopipette. This permits transparent This paper focuses on fountain pen integration with nanolithography (FPN) and its evolution spectroscopic into a powerful generally applicable methodologies chemical writing method on many such as Raman length scales with many surfaces for chemical characterization and utilizing a wide variety of inks, of the written including gases. structures. (b) The technique in general uses a Deposition can quartz cantilevered nanopipette with occur with a a tip highly exposed to the optical axis, variety of inks and surfaces and as seen in Figure 1. Such an exposed tip evident that its generality arises from also have an influence on the writing, can be controlled has great advantages over other probe critical wetting interactions between the namely the nanopipette aperture, the with voltage or technologies where the tip is generally ink and surface that is chosen (Figure 1b). speed (see Figure 5), the imposed force pressure and with obscured from above by the cantilever For comparison, in DPN the molecules of the tip to the surface (set-point) (see other standard [3]. This geometry permits effective are delivered to the surface through a Figure 6), the mode of AFM operation AFM parameters probe placement within an already water meniscus and the deposition rate (contact or non-contact) etc. Generally also adding additional control. written structure (see Figure 2). is dependent on the diffusion rate of each humidity effects are not as critical as The wetting Another aspect of this attribute is that molecule. This process has drawbacks in DPN which depends on an aqueous interactions it allows for multiple independently since each molecular ink is limited solely bridge that arises from the surface between the controlled probes to be brought within to its corresponding substrate, so the wetting. nanopipette, touching distance of the multiple diffusion process is relative slow and the Presently, knowledge is rapidly the ink and the surface are critical tips (see Figure 1a) [4]. As a result, method only works in contact with the accumulating in the FPN field that in the generality of one can have writing nanopipettes surface. allows for the effective use of the the FPN process. in one or multiple probes, while an In FPN there are several important generality of the method in numerous alternate probe can be used for on-line parameters that readily allow for areas of fundamental and applied science. high resolution imaging and writing control of the ink deposition. One such This article is aimed at leading the reader characterization. Furthermore, other parameter is the induction of pressure by to an understanding of these advances. functional probes, such as electrical, either imposed voltages over the column thermal, electrochemical and Kelvin of liquid [6], or by the imposition of Materials and Methods probes, can also be on-line to investigate a defined pressure from the back of a Probes and Feedback the writing process at different time liquid column. In the case of gases, this The probes used were glass cantilevered points. A movie of FPN with multiprobe pressure can be differential between the nanopipette capillaries with diameters AFM characterization can be seen on the inside of the pipette and the surrounding that varied from 35 nm to 10 web [5]. environment (see Figure 5). In addition micrometers. These probes were used In FPN it is becoming increasingly to such control, several AFM parameters either with beam bounce amplitude MicroscopyandAnalysis | April 2014 Scanning Probe Microscopy Supplement 11 fountain pen nanochemistry sodium cholate. In Figures 2a and 2b the writing could be accomplished on n-type silicon and silicon oxide surfaces. In Figure 2c, the CNTs are written on an organic electron beam photoresist layer. In Figure 2d an aqueous salt solution with 20% wt. silver nitrate is the ink while in Figures 2e and 2f a silver nanoparticle (50 nm dimension) in Downol DB suspension (Gift from Xjet Solar Ltd, Israel) is written. In Figures 2d and 2e, the solution and the suspension, respectively, were written on gold lines. In Figure 2d the previously written lithographic structures had dimensions and separations that were too small to see in the optical microscope as resolved features but were clearly visible in the scanning electron microscope image shown. In Figure 2e even previously written structures by other lithographic processes on the 1.5 µm level could be targeted and written on, due to the completely free axis from above as a FIGURE 2 result of the probe and SPM system A generality of results feedback or complexed to tuning than that achieved by the best beam- geometry. In Figure 2f, the writing with FPN. (a,b,c) Deposition of CNTs forks for implementing tapping-mode bounce technologies available today across an interface between the gold and in aqueous solution normal force tuning fork operation. Tip [7]. Therefore, the ultimate in force the SiO2 allowed for an AFM electrical with surfactants. (a) approach, feedback and scanning are microscopy can be readily integrated probe to be placed on the SiO2 end of the Deposition on an under atomic force microscope control. with the chemical writing process and written structures for the measurement n-type silicon substrate. In all the experiments described in this this is presently in its infancy in FPN. of conductivity of the line with a counter (b) Deposition on SiO2 substrate demonstrating article the SPM instruments employed Both this aspect of sensitive force electrode on the gold pad. the capability of writing for the FPN process were the Nanonics detection with no jump-to-contact and on previously deposited MultiView 1000 and 4000 series adhesion ringing allow for relatively Control of the Writing lines by FPN. (c) SEM (Nanonics Imaging Ltd., Jerusalem, difficult tasks such as writing on, for Process: Voltage image of deposition Israel). example, thin carbon membranes The control of the writing process with of carbon nanotubes As noted above, both contact and non- that are found in certain transmission FPN by imposed force of voltage or on an organic PMMA contact AFM can be used with FPN. The electron microscopy grids. pressure is seen next in Figures 3-5. For layer covering an SiO2 substrate. The line advantage of non-contact is that one can the voltage control the nanopipette with widths are 170-250 nm consider writing on very soft surfaces Surfaces and Inks its insulating glass walls allows for a and cannot be seen which would be difficult to access with Table I summarizes the surfaces and variety of voltage options to be provided, by a regular optical contact mode operation. In addition, inks that have been used in various as indicated in Figure 3a. microscope. (d) SEM image of depostion tuning forks allow for true non-contact combinations in the writing process with Figures 3b-d and 4d-g show deposition of 20% wt. of silver operation. This is difficult to achieve FPN. Many of these examples are shown of a 1.4 nm gold nanoparticle suspension nitride in aqueous with beam bounce silicon cantilever in this article, or are in the published (Nanogold, Nanoprobes, Yaphank, solution on 200 nm methodologies due to jump-to-contact literature, and will be explained below. NY, USA) in an organic solvent, which width gold structures instabilities in AFM silicon probes when in this case was methanol (1 mM/ml). lithographically they approach to less than ~10 nm above Results Voltage was shown to work even with imprinted on an SiO2 subtrate. (e, f) Writing the surface. The results shown in the Figures such an organic solvent. The voltage lines of 40% wt. 50 nm In tuning forks, this unique behaviour demonstrate the generality of inks and control allows for the use of pipettes with silver particles in Donol of no jump-to-contact and no-adhesion surfaces in the FPN writing process, as dimensions as small as 35 nm that are DB suspension.

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