Symposium Organizers
Graham Cross Trinity College
Andre Schirmeisen University of Muenster
Armin Knoll IBM Research-Zurich
Marco Rolandi University of Washington
FF1: Nanoimprint Fabrication Methods
Session Chairs
Graham Cross
Clivia Sotomayor Torres
Monday PM, November 28, 2011
Room 202 (Hynes)
9:30 AM - FF1.1
Deterministic Fabrication of Hierarchically Ordered, Monolithic Nanotextures by Directional Photofluidization Lithography and Example of Its Use in Superhydrophobic Surfaces.
Hong Suk Kang 1 , Seungwoo Lee 1 , Jung-Ki Park 1 2
1 Graduate school of EEWS, KAIST, Daejeon Korea (the Republic of), 2 Department of Chemical and Biomolecular Engineering, KAIST, Daejeon Korea (the Republic of)
Show AbstractOver the last decade, the fabrication of hierarchically ordered, monolithic nanotextures have attracted a great interest due to its promising application such as advanced photonics and interface sciences. Even if many impressive results have been achieved, most of established methods still suffer from several drawbacks including low throughput, inherently having defects, and multistep process. Herein, to overcome such limitations, we have suggested a new strategy for the generation of hierarchically ordered, monolithic nanotextured surfaces by directional photofluidization lithography (DPL).[1-6] DPL enable the fabrication of a variety of nanostructural motifs with precisely controlled structural features in a very unique way. The key of DPL is to use the photo-reconfigurable polymer (i.e., azopolymer) arrays instead of a conventional colloidal nanosphere, photoresist arrays, and polydimethylsiloxane (PDMS) arrays. By taking advantages of DPL, the structural features of hierarchically ordered nanotexture (i.e., shapes and modulation heights) could be precisely and simply tuned by adjusting the beam variables including polarization, irradiation time, and incident angle. Furthermore, in a more practical point of view, this method also can provide an effective tool for the control of the wettability due to its advantage of simple and deterministic tuning of the structural features. Besides the fabrication of diverse hierarchically ordered, monolithic nanotextures, we believe that this clever experimental strategy and resulting phenomenological finding can give us an important experimental clue for the better understanding of underlying mechanism of surface relief gratings formation onto photo-reconfigurable azopolymer film, which has been a long-lasting question. Therefore, this work can beat the limitation of our current understanding about photo-induced azopolymer movement during light irradiation and, in turn, will greatly extend our ability to fabricate diverse nanotextured structures.Reference1)Lee, S.; Shin, J.; Kang, H.S.; Lee, Y.-H.; Park, J.-K. Adv. Mater. 2011, DOI: 10.1002/adma.201100662.;2)Lee, S.; Kang, H.S.; Park, J.-K. Adv. Funct. Mater. 2011, 21, 1770. 3)Lee, S.; Shin, J.; Lee, Y.-H.; Park, J.-K. ACS Nano 2010, 4, 7175. 4)Lee, S.; Shin, J.; Lee, Y.-H.; Fan, S.; Park, J.-K. Nano Lett. 2010, 10, 296. 5)Lee, S.; Jeong, Y.-C.; Park, J.-K. Appl. Phys. Lett. 2008, 93, 031912. 6)Lee, S.; Jeong, Y.-C.; Park, J.-K. Opt. Express 2007, 15, 14550.
9:45 AM - FF1.2
A Thin Film Transistor on Poly(Ethylene Naphthalate) Foil Using Step-and-Flash Imprint Lithography.
Pieter Moonen 1 , Boris Vratzov 2 , Wiljan Smaal 3 , Gerwin Gelinck 3 , Erwin Meinders 3 , Jurriaan Huskens 1
1 Molecular Nanofabrication, University of Twente, Enschede Netherlands, 2 , NT&D - Nanotechnology and Devices, Aachen Germany, 3 , Holst Centre / TNO, Eindhoven Netherlands
Show AbstractAdvanced and flexible organic electronic devices demand high resolution patterning techniques that, for the sake of low-cost fabrication, can be integrated in high throughput manufacturing lines like roll-to-roll (R2R) assemblies. The low-cost, alternative lithography technique nanoimprint lithography (NIL) [1] provides high resolution patterning combined with short process times. The enhanced functionality of flexible electronic devices (bendable, rollable) combined with low-weight and possible transparency, enables integration into products such as thin-film-transistor (TFT) displays. However, the surface flatness and dimensional stability of the flexible substrates needs to be well controlled to obtain good registration accuracy for multi-layer devices, like TFTs. A new thermal imprinting technique, double layer NIL [2], has been developed to imprint multi-dimensional structures from the sub-micron to millimeter regime. It compensates the inhomogeneous residual layer thickness arising from the wavy foils by depositing resist on mold and substrate. Double layer NIL offers the unique capability of combining two heterogeneous resists with, for example, different surface energy to control wetting.In this paper, the fabrication of flexible TFTs on poly(ethylene naphthalate) foil in a bottom gate, bottom contact architecture is reported (Figure 1). All functional metal – insulator – metal layers were patterned by step-and-flash imprint lithography [3] on foil, allowing sub-micrometer alignment of the source-drain electrodes to the gate. The foils have been reversibly glued to a carrier to enhance the dimensional stability during imprinting. Flexible TFTs with channel lengths from five micron down to the sub-micrometer regime have been fabricated on PEN foil (Figure 2). The semiconductor has been deposited as a blend of TIPS pentacene and polystyrene by inkjet printing [4]. Technology challenges like overlay accuracies, dimensional stability of the flexible substrates and pattern fidelity will be addressed as well.In the future, the here developed SFIL process for the fabrication of flexible TFTs is to be further developed, allowing self-aligned patterning of the source and drain electrodes in respect to the gate, making alignment steps obsolete. The final aim is the integration into a R2R assembly, to fabricate low cost, high throughput flexible electronic devices.[1]H. Schift, J. Vac. Sci. Technol. B 2008, 26, 458-480.[2]P. F. Moonen, I. Yakimets, M. Peter, E. R. Meinders, J. Huskens, ACS Appl. Mater. Interfaces 2011, 3, 1041-1048. [3]P. Ruchhoeft, M. Colburn, B. Choi, H. Nounu, S. Johnson, T. Bailey, S. Damle, M. Stewart, J. Ekerdt, S. V. Sreenivasan, J. C. Wolfe, C. G. Willson, J. Vac. Sci. Technol. B 1999, 17, 2965-2969.[4]X. Li, W. T. T. Smaal, C. Kjellander, B. van der Putten, K. Gualandris, E. C. P. Smits, J. Anthony, D. J. Broer, P. W. M. Blom, J. Genoe, G. Gelinck, Org. Electron. 2011, 12, 1319-1327.
10:00 AM - **FF1.3
Nano-Crossbar Circuits Fabricated Using Nanoimprint Lithography.
Wei Wu 1 , Robert Walmsley 1 , Qiangfei Xia 1 , Jianhua Yang 1 , Max Zhang 1 , William Tong 1 , Warren Robinett 1 , Wen-di Li 1 , Gilberto Medeiros-Ribeiro 1 , Shih-Yuan Wang 1 , R. Stanley Williams 1
1 HP labs, Hewlett-Packard, Palo Alto, California, United States
Show AbstractSemiconductor industry has enjoyed great successes by following the “Moore’s law” for more than four decades. With the end of the roadmap looming in the horizon, great efforts have been made to look for the alternatives for “post-Si” electronics. Transition oxide based electronics (i.e. memristor) is one of the most promising candidates. Memristor is a type of resistive RAM device. It stores the information by ion movements inside the switching material, instead of charge trapping as in other conventional memory devices. I will present our work on memristor nano-crossbar circuits fabricated using nanoimprint lithography (NIL). We have fabricated several generations of nano-crossbar memory circuits, with record-high densities, and have also successfully integrated memristor and Si CMOS circuits. The key enabling technology is NIL. It is a cost-effective nano-patterning technology based on the mechanical deformation of a resist. At HP labs, we have not only designed and constructed five generations of nanoimprinters, but also invented several relating technologies to improve NIL. The latest nanoimprint machine, which is capable of both high-resolution patterning and overlay alignment, will be highlighted in the presentation too.
10:30 AM - FF1.4
Roll-to-Roll Nanoimprinting Metamaterials.
Anton Greenwald 1 , Jae Ryu 1 , Yisi Liu 1 , Rana Biswas 3 , Myung-Gyu Kang 4 , L. Guo 2
1 , Agiltron, Inc., Woburn, Massachusetts, United States, 3 Microelectronics Research Center, Iowa State University, Ames, Iowa, United States, 4 Center for Nanoscale Science and Technology, National Institute of Standards and Technology, Gaithersburg, Maryland, United States, 2 Electrical Engineering, University of Michigan, Ann Arbor, Michigan, United States
Show AbstractWe investigated continuous fabrication of large area 2-D metamaterial comprising a metal dot array on a dielectric coated substrate. We demonstrated patterning of metal dots arrays of varying patterns and shapes with diameter of about 2.5 µm and metal-to-metal spacing from 0.5 to 2.5 µm using a nano-imprinting stamp on a roller. The pattern was first fabricated on a standard photolithography mask, reproduced onto a silicon wafer master mold, and then transferred to a flexible polymer mold that was wrapped around a metal roller. The method was used to pattern a thin Al layer on top of SiO2 on a flexible polymer substrate. The aluminum was coated with a resist and the roller moved over the substrate with adjustable speed and pressure to imprint the fine pattern into the resist. The resist was cured, and a very thin layer of residual resist was removed by RIE, followed by a standard etching treatment for patterning the aluminum layer. Resist was left on some samples to test it as protection for the thin metal. The as-etched pattern had very few defects and the optical properties of the metamaterial were excellent and correlated well with simulations. Design calculations were performed with both commercial and custom software. Our achieved objective was to show that we could vary the resonance from a narrow, sharp absorption spike with FWHM 0.5µm for a central wavelength of 7 µm to a broad absorption peak with FWHM greater than 4 µm for a central wavelength of 10 µm. Infrared reflectance spectra were measured by an FTIR at different angles with or without the polymer resist coating. The coating had little effect optically and could be used to protect the thin metal film. This work has shown that low cost, rapid roll-to-roll processing of 2-D metamaterial structures is possible.This effort was partially supported by the Naval Surface Warfare Center contract No. N00178-11-C-1015 and by the Air Force Research Laboratory contract FA9551-11-C-0033.
10:45 AM - FF1.5
Nanoimprinting with Amorphous Metals.
Golden Kumar 1 , Jan Schroers 1
1 , Yale University, New Haven, Connecticut, United States
Show AbstractThe random structure in amorphous metals (AM) is homogeneous down to the atomic length scale and results in highest strength and hardness, combined with other attractive properties for a structural material. Even more unique is the softening behavior of AM; they can be considered high strength metals that can be processed like plastics. Recently, we showed that some AM can massively replicate features as small as ~10 nm through direct embossing by utilizing favorable wetting conditions between the AM and the mold material[1]. The unique softening behavior in combination with a wider range of softening temperatures, which span a range of 50C-500C among AM provides a versatile toolbox for nanoimprinting. This includes the ability to use AM as a hard mold or, alternatively, a soft imprint material. This toolbox can be used for example in nanoimprint lithography where the robust AM would replace the fragile Si mold in the imprinting process. The low softening temperature of AM and the associate low strength permits to directly write onto the AM as in nano probe lithography. Furthermore, the ability to erase multiple times (103-104 times) features through the action of the surface tension alone before crystallization sets in[2], can be combined with direct writing and used for high density data storage. 1.G. Kumar, H.X. Tang, and J. Schroers, Nanomoulding with amorphous metals. Nature, 2009. 457(7231): p. 868.2.G. Kumar and J. Schroers, Write and erase mechanisms for bulk metallic glass. Applied Physics Letters, 2008. 92(3): p. 461.
11:30 AM - **FF1.6
Development of Nanometrology Methods for Nanopatterning and Self-Assembly.
Clivia Sotomayor Torres 1 3 4 , Timothy Kehoe 1 , Nikolaos Kehagias 2
1 Phononic and Photonic Nanostructures, Catalan Institute of Nanotechnology, Bellaterra Spain, 3 , Institució Catalana de Recerca i Estudis Avançats (ICREA), , Barcelona Spain, 4 Dept. of Physics, UAB, Barcelona Spain, 2 Nanofabrication Division, Catalan Institute of Nanotechnology, (Bellaterra) Barcelona Spain
Show AbstractOne of the major research needs to enable the transfer of novel nanomaterials and nanodevices to end users is in the field of nanometrology methods compatible with a production environment, capable of sub 20 nm feature size resolution in the first instance and eventually capable of chemical and biological metrology.We will address issues of tracebility and methods to establish metrology methods in the nanoscale that will assist in setting standards to enable comparison and reliability studies of nanostrutcures.We will discuss in particular two methods: sub-wavelength optical diffraction applied to nanoimprinted materials and image analysis for ordering in self assembled arrays of nanoparticles.Furthermore, we will discuss emerging methods based on acoustic phonons for sub-5 nm dimensional metrology.
12:00 PM - FF1.7
Continuous Patterning of Nanogratings by Nanochannel-Guided Lithography on Liquid Resists.
Jong G. Ok 1 , Hui Joon Park 2 , Moon Kyu Kwak 3 , Carlos Pina-Hernandez 3 , Se Hyun Ahn 1 , L. Jay Guo 2 3
1 Mechanical Engineering, University of Michigan, Ann Arbor, Michigan, United States, 2 Macromolecular Science and Engineering, University of Michigan, Ann Arbor, Michigan, United States, 3 Electrical Engineering and Computer Science, University of Michigan, Ann Arbor, Michigan, United States
Show AbstractNanoscale grating structures have drawn significant research interest as they can be utilized in various practical devices such as optics, displays, and biosensors. In particular, the new Dynamic Nanoinscribing (DNI) can create seamless large-area nanograting structures at high speed [1]. DNI uses a slice of rigid (e.g., Si) grating mold to mechanically inscribe a solid metal or polymer surface at ambient or heated conditions to create nanostructures. However, the elastic recovery of the plastically deformed solid surfaces after the release of mechanical force limits the aspect ratio of the inscribed structure, especially for small period gratings. This cannot satisfy the need for many applications such as metal wire-grid polarizers where higher aspect-ratio and well-defined cross-sectional profiles are highly desirable.To address these issues, we have developed a nanopatterning technique by adopting liquid resist materials to a high-throughput nanoinscribing process, aiming to achieve high-speed and low-cost fabrication of continuous nanograting structures for large-area optoelectronic applications. Whereas a relatively large force is required to ‘inscribe’ nanopatterns on a solid substrate by plastically deforming the material, a liquid resist can readily ‘infiltrate’ the openings in the mold grating upon contact under slight mechanical force. These nanochannel-guided liquid streaks are continuously extruded from the contact region as the mold moves along the substrate surface. We used UV-curable epoxy-silsesquioxane (SSQ) [2], a viscous liquid polymer that can be cross-linked to form high-modulus material upon UV curing in this process, which enables continuous formation of nanograting patterns without elastic recovery. To ensure the success of the nanopatterning process by this “NanoChannel-guided Lithography (NCL)”, the substrate material should have non-wetting property with respect to the liquid resist used in the process. The shallow but plastically deformed groove features on the substrate along with its non-wetting characteristics prevent the immediate reflow of the as-formed liquid nanograting structures until the pattern is fully cured by UV light. The final nanograting geometry can be readily tuned by the substrate surface modification that adjusts its non-wetting property to the liquid resist, and also by the processing temperature that controls the viscosity of the liquid resist and therefore the nanochannel filling height during the process.Such a ‘direct-write’ NCL patterning of liquid resists is a gentler process than the previous DNI technique and result in much more faithful pattern replication for small period and high aspect ratio structures. This new technique may open a way to mass-produce large-area, high-quality nanogratings at low cost.[1] S.-H. Ahn and L. J. Guo, Nano Lett. 9, 4392-4397, 2009.[2] C. Pina-Hernandez, L. J. Guo, and P.-F. Fu, ACS Nano 4, 4776–4784, 2010.
12:15 PM - FF1.8
Nanoimprint Lithography of PS-PDMS Block Copolymers for Extreme Resolution Nanofabrication.
Brett Helms 1 , Vincent Voet 1 , Teresa Pick 1 , Sang-Min Park 1 , Deirdre Olynick 1
1 The Molecular Foundry, Lawrence Berkeley national Laboratory, Berkeley, California, United States
Show AbstractBlock copolymer (BCP) lithography is a powerful technique to write periodic arrays of nanoscale features into substrates at exceptionally high densities. In order to place these features at will on substrates, nanoimprint offers a deceptively clear path toward high throughput production: nanoimprint molds are reusable, promote graphoepitaxial alignment of BCP microdomains within their topography, and are efficiently aligned with respect to the substrate using interferometry. Unfortunately, when thin films of BCPs are subjected to thermal nanoimprint, there is an overwhelming degree of adhesion at the mold−polymer interface, which compromises the entire process. Here we report the synthesis of additives to mitigate adhesion based on either PS or PDMS with short, interface-active fluoroalkyl chains. When blended with PS-b-PDMS BCPs and subjected to a thermal nanoimprint, fluoroalkyl-modified PS in particular is observed to substantially reduce film adhesion to the mold, resulting in a nearly defect-free nanoimprint. Subsequent lithographic procedures revealed excellent graphoepitaxial alignment of sub-10 nm BCP microdomains, a critical step toward lower-cost, high-throughput nanofabrication.
12:30 PM - FF1.9
Microcontact Printing of Self-Assembled Chitin Nanofibers.
Chao Zhong 1 , Adnan Kapetanovic 1 , Yingxin Deng 1 , Marco Rolandi 1
1 , University of Washington, seattle, Seattle, Washington, United States
Show AbstractChitin is an ideal biopolymer for fabrication of biocompatible devices. It is naturally abundant, and has many appealing properties including high mechanical strength, biocompatibility, biodegradability and anti-microbial properties. In nature, chitin is often weaved into well-ordered fibril bundles or arrays. However, integration of chitin nanofibers at the micro and nanoscale is a difficult task because of chitin poor solubility. In our previous work, we have developed a bottom-up approach for producing self-assembled chitin nanofibers (3nm) from hexafluoro 2-propanol (HFIP) solution. Here, we integrate the simple self-assembly strategy with microcontact printing. Patterned self-assembled chitin nanofiber structures with sub 100 nm features are achieved. Chitin self-assembly in the confined environment of the elastomeric stamp is concentration, aging time and geometry dependent. As a result, these factors can be used to control both the direction and geometry of the resulting nanofiber-based structures.
12:45 PM - FF1.10
Chemical and Rheological Control over Hybrid Silica Coatings during Nanoimprint: Application for Light Extraction.
Alban Letailleur 1 2 3 , Cedric Boissiere 2 , Francois Ribot 2 , Clement Sanchez 2 , Jeremie Teisseire 1 , Etienne Barthel 1 , Elin Sondergard 1 , Christophe Couteau 3 , Gilles Lerondel 3 , Nicolas Chemin 4
1 Surface du Verre et Interfaces, Saint-Gobain Recherche - CNRS, Aubervilliers France, 2 Chimie de la Matière Condensée de Paris, Collège de France - Université Pierre et Marie Curie, Paris France, 3 ICD - Laboratoire de Nanotechnologies et d'Instrumentation Optique, Université de Technologies de troyes, Troyes France, 4 Composites and Coatings, Saint-Gobain Recherche, Aubervilliers France
Show AbstractIn light emitting devices, a large amount of the light produced by the active layer is trapped inside the device because of internal reflection. Patterning the different interfaces induces an index gradient and light scattering and can therefore lead to an increase of the light output. Among the existing methods, Nanoimprint Lithography (NIL) emerges as a simple route for surface patterning at the sub-micrometer scale over large areas. To avoid multiple step processing and the poor stability of polymers resins, imprint of functional materials is required.Hybrid sol-gel materials form an innovative class of resists for NIL. They are based on the solution processing of organic precursors to obtain metal oxide. For instance we previously demonstrated the replication of patterns with sub-100 nm lateral size and aspect ratio greater than 1 into hybrids sol-gel silica, using low temperature processing. Fully inorganic silica structures can be obtained after thermal annealing (1). Due to their low dielectric constant, nanopatterned silica coatings are very suitable for applications in photonics, and integration in displays.To achieve high resolution in nanoimprinting, it is crucial to understand the rheological properties of these new resists. Using a combination of dynamic mechanical and electric analysis, we demonstrate that these silicates exhibit a glass transition below room temperature and that the fast increase of this Tg leads to the vitrification and provides long-term stability to the coating. In terms of material structure, we further demonstrate by Infrared spectroscopy that the vitrification is connected to a condensation threshold. (2) This combination of low viscosity and high reactivity enables fast and conformal imprint over several tens of cm2. Furthermore, we demonstrate how the initial material viscosity can be adjusted by changing the elaboration chemistry and how the cavity filling is modified in the imprint process.(3) Finally, we used the solution processing to introduce colloidal quantum dots inside the silica layer, and successfully imprinted the resulting layer.(4) These systems are suitable for light conversion and extraction. As it absorbs around 400 nm and emits light in the visible range, such a layer can act as a conversion layer in LED devices. Furthermore, the light output in the patterned area increased 60 % compared to the flat surfaces.References: 1) Peroz, C.; Chauveau, V.; Barthel, E.; Sondergard, E. Advanced materials 2009, 21, 5552) Letailleur, A.; Teisseire, J.; Chemin, N.; Barthel, E.; Sondergard, E. Chem. Mater. 2010, 22, 31433) A. A. Letailleur, F. Ribot,, C. Boissière, C. Sanchez, J. Teisseire , E. Barthel, N. Chemin, J Am Chem Soc, submitted.4) A. A. Letailleur, Th. Richardot, C. Boissière, C. Sanchez, C. Couteau, G. Lérondel, E. Barthel, E. Søndergård, N. Chemin, and François Ribot, Advanced materials, submitted.
FF2: Assembly by Adhesive Transfer and Other Mechanical Techniques
Session Chairs
John Rogers
Kenneth Shull
Monday PM, November 28, 2011
Room 202 (Hynes)
2:30 PM - **FF2.1
Mechanics of Nanotransfer Printing for Applications in Electronics and Metamaterials.
John Rogers 1
1 , University of Illinois, Urbana, Illinois, United States
Show AbstractSoft, viscoelastic stamps provide useful vehicles for selective transfer of nanostructures from one substrate to another, in a way that can be exploited both for heterogeneous integration and nanofabrication. We describe the mechanics of advanced forms of transfer printing, and then outline the use of these methods in the construction of flexible/stretchable electronic devices, and large-area three dimensional metamaterials.
3:00 PM - FF2.2
Shear-Enhanced Adhesiveless Transfer Printing Techniques for Nanoscale Materials Assembly.
Andrew Carlson 1 , Hyun-Joon Kim-Lee 2 , Jian Wu 3 , Paulius Elvikis 4 , Placid Ferreira 4 , Yonggang Huang 3 , Kevin Turner 2 , John Rogers 1 4
1 Materials Science and Engineering, University of Illinois, Urbana-Champaign, Urbana, Illinois, United States, 2 Mechanical Engineering, University of Wisconsin-Madison, Madison, Wisconsin, United States, 3 Civil and Environmental Engineering, Northwestern University, Evanston, Illinois, United States, 4 Mechanical Science and Engineering, University of Illinois, Urbana-Champaign, Urbana, Illinois, United States
Show AbstractMeeting the performance demands of many emerging microelectronic and optoelectronic technologies often require devices fabricated by large-scale integration of disparate classes of nanomaterials into spatially organized, functional arrangements. Transfer printing, a recently developed process which utilizes an elastomeric stamp to mediate transfer of prepatterned micro/nano-objects (i.e., ‘inks’, semiconducting nanomaterials and others) between a donor and receiver substrate, provides a scalable route for direct integration of diverse nanostructures and materials into single, unified systems. Transfer printing efficiency, particularly separation of the nanomaterial ‘ink layer’ from the viscoelastic stamp element, can be enhanced by engineering the stamp/ink interface to support mechanical loads that alter its effective adhesive strength. We demonstrate how targeted shear loading of single-post polydimethylsiloxane (PDMS) stamps can be used to reduce normal direction forces necessary to separate the stamp from silicon membranes in a controlled, repeatable manner during printing. Experimental studies combined with Finite Element (FE) modeling reveal critical factors influencing the shear printing process including geometrical constraints on stamp design and local stress distributions at the stamp/ink interface. Additionally, analytical expressions for shear strain in the stamp are developed. Systematic adhesiveless transfer printing yield studies and examples of partially suspended, overhanging structures and multilevel configurations of silicon membranes provide key practical demonstrations of shear-assisted printing capabilities.
3:15 PM - FF2.3
Measuring Micromechanical Adhesive Inking and Printing of Carbon Nanotube and Silver Nanowire Transparent Thin Films Using a Nanoindenter.
Evelyn Doherty 1 , Graham Cross 1
1 Crann, Trinity College Dublin, Dublin Ireland
Show AbstractAn emerging technique in nanofabrication is the use of the micro-contact adhesion of an elastomeric stamp to transfer nano-objects between source and target substrates. This technique has many outstanding advantages including the precise inking and printing of nano or micro objects of varied complexity1 for electronics, optical and medical applications, without the use of additional chemicals or processes such as etching. We have conducted a local mechanical analysis of the inking and printing of thin films of transparent silver nanowire and carbon nanotube networks (nano-networks). A nanoindenter was used with a novel micrometer scale elastomeric polydimethylsiloxane (PDMS) transfer tool to record and correlate displacement, load and dynamic stiffness with video microscopy analysis of transfer processes. The viscoelastic contact dynamics of our thin film PDMS transfer tool is tuned by varying parameters such as PDMS surface energy, complex modulus, film thickness, peak load, and unloading rate to influence interfacial energy release rates and detailed contact stress distributions. The mechanical analysis is enhanced by the establishment of a relationship between small amplitude dynamic contact stiffness and true contact size. Control of these parameters facilitates realization of transfer functions including seeding, inking and printing over a wide process space. The mechanisms of rupture and peeling of the nano-network films are thus investigated in terms of interfacial fracture due to these tuned parameters. Our results indicate that the detailed stress distribution in the contact is responsible for controlled and symmetric peeling and tearing of the nano-networks. We investigate the role of cavitation and cohesive failure of the PDMS with the underlying substrate and its role in the inking effect. We report on the transfer as a function of both PDMS tool and nano-network characteristics such as thickness and porosity. Comparisons and analysis will be presented with existing literature2,3 for systems of a similar configuration which have examined the inking and printing of elastic, continuous thin films. References: 1.Onoe, Shimoyama et al Three-dimensional integration of heterogeneous silicon micro-structures by liftoff and stamping transfer J. Micromechanics & Microengineering (2007) 2.Feng, Rogers et al Competing fracture in kinetically controlled transfer printing, Langmuir 23 (2007)3.Shull et al Adhesive Transfer of Thin Viscoelastic Films Langmuir (2004)
3:30 PM - **FF2.4
Adhesion Issues in Pattern Transfer.
Kenneth Shull 1
1 Materials Science and Eng., Northwestern University, Evanston, Illinois, United States
Show AbstractContact transfer of a thin layer from one surface to another forms the basis of a variety of pattern transfer processes. In these processes material transfer is controlled by the relative adhesion of the layer to a supporting surface and to a second surface that is brought into contact with it. The relevant transfer criterion can be posed as a fracture mechanics problem, where a contact line moves at a velocity that is determined by the applied energy release rate. Polymeric materials generally have a viscoelastic character, in which case the full functional relationship between the energy release rate and the crack velocity must be specified in order to quantify the adhesive behavior. In this talk the factors affecting this relationship will be summarized, and fracture mechanics concepts will be used to illustrate the factors enabling a thin film supported on a flexible substrate to be cleanly transferred from one surface to another.
4:30 PM - FF2.5
Electroplate-and-Lift (E&L) Lithography on Reusable, Patterned Ultrananocrystalline Diamond (UNCD) Templates for Rapid Prototyping of Micro- and Nanowires.
Lori Lepak 1 , Anirudha Sumant 2 , Ralu Divan 2 , Daniel Rosenmann 2 , Orlando Auciello 2 3 , David Seley 1 , Daniel Dissing 1 , Suzanne Miller 2 , Julia Weber 1 , Jessica Nordstrom 1 , Dylan Jones 1 , Corina Grodek 1 , Timea Hohl 1 4 , Bradley Stroik 1 , Morgan O'Connell 1 , John Knauf 1 , Michael Zach 1
1 Department of Chemistry, University of Wisconsin -- Stevens Point, Stevens Point, Wisconsin, United States, 2 Center for Nanoscale Materials, Argonne National Laboratory, Argonne, Illinois, United States, 3 Materials Science Division, Argonne National Laboratory, Argonne, Illinois, United States, 4 Department of Experimental Physics, University of Debrecen, Debrecen Hungary
Show AbstractElectroplate-and-Lift (E&L) lithography has been developed as fast, simple, scalable technique for the controlled, solution-based, electrochemical synthesis of patterned metallic and semiconducting nano- and microwires. The wires are electrodeposited onto a reusable, non-sacrificial, multi-layered, lithographically patterned ultrananocrystalline diamond (UNCD)TM template. The template is made from alternating layers of UNCD, which is insulating, and nitrogen-incorporated UNCD (N-UNCD), which has nearly metallic conductivity. UNCD is used to isolate the top and bottom surfaces of the N-UNCD layer from the electrochemical bath. The diamond layers are lithographically patterned and dry etched to expose only edges of the N-UNCD layer, which is 80 nm thick. The initial nucleation of the nanowire is thus confined to the patterned edges of the N-UNCD. While the thickness of the N-UNCD layer establishes the minimum wire thickness, the maximum wire diameter is determined solely by the deposition time, independent of feature sizes in the template. Following electrodeposition, the nanowires may be removed by mechanically lifting them away from the template with scotch tape or other polymers, thus regenerating the template surface for subsequent depositions. Wires of the same or a different diameter, composed of any desired electrochemically depositable material, may subsequently be plated. Unlike all other methods of patterning nanowires, E&L lithography allows patterned nanowires to be quickly mass-produced, without requiring any additional vacuum or clean room processing after the initial fabrication of the template. This permits the study of nanoscale phenomena with minimal equipment and entry-level personnel. As a consequence, E&L lithography greatly expands the breadth of micro- and nanomaterials research projects which may be feasible at primarily undergraduate institutions, small companies without access to state-of-the-art clean rooms, and even institutions well-equipped with extensive fabrication facilities.
4:45 PM - FF2.6
PRINT: A Roll-to-Roll Method for the Fabrication of Shape and Size Specific NanoParticles.
Kevin Herlihy 1 , Mary Napier 1 , Marc Kai 2 , Jillian Perry 1 , Joseph DeSimone 1 2 3
1 Lineberger Comprehensive Cancer Center, UNC Chapel Hill, Chapel Hill, North Carolina, United States, 2 Chemical and Biomolecular Engineering, North Carolina State University, Raleigh, North Carolina, United States, 3 Chemistry, University of North Carolina, Chapel Hill, North Carolina, United States
Show AbstractA variety of top-down particle fabrication methods currently exist. These methods are unique in that they sculpt bulk materials to make nanomaterials with sizes, shapes and other interesting properties. Using the Particle Replication In Non-wetting Templates (PRINT®) process, we use elastomeric molds to gently fabricate micro- and nanoparticles. Molds are secured to a robust yet flexible poly(ethylene terephthalate) backing which gives the ability to scale up particle fabrication using a continuous roll-to-roll process, something that is not easily translated to other top-down fabrication techniques. The ability to control particle size, shape and composition is demonstrated. Particles are fabricated using a variety of matrices from pure drug to biologics to biodegradable polymers. Janus particles fabricated via multilayer filling steps or surface modification steps will also be discussed.
5:00 PM - FF2.7
Monolithic Integration of Continuously-Tunable Metallic Bumps, Grooves, and Apertures for Plasmonics and Nanophotonics.
Nathan Lindquist 1 , Timothy Johnson 1 , David Norris 2 , Sang-Hyun Oh 1
1 Electrical and Computer Engineering, University of Minnesota, Minneapolis, Minnesota, United States, 2 Optical Materials Engineering Laboratory, ETH Zürich, Zürich Switzerland
Show AbstractPrecise fabrication of metallic nanostructures is critical for the emerging field of plasmonics and nanophotonics. Indeed, advances in nanofabrication technologies have to a large degree driven the rapid development of surface plasmon optics. To build a functional device and to carefully study surface plasmon physics, the precise engineering of metallic nanostructures is necessary. However, the integration of arbitrary arrangements of smoothly patterned bumps, grooves, and apertures over large areas remains a significant challenge. These implementation difficulties are compounded because as-deposited metal films are typically rough—which can limit surface plasmon propagation, degrade the performance of the device, and lead to sample-to-sample variations. In this abstract, we present a fabrication technique that uses template stripping of patterned metals for the large-scale, monolithic integration of bumps above, grooves into, and apertures through an optically-thick, ultrasmooth metallic film. We first fabricate a high-quality, reusable silicon template with focused ion beam (FIB) milling and FIB-induced deposition. Then, via template stripping, we show high-throughput, repeatable fabrication of metallic nanostructures with features that vary smoothly from ~100 nm above the metal surface to ~100 nm into the metal surface with 1-2 nm geometric tuning precision. Nanometric apertures through the metallic film are also possible. Such continuously-tunable plasmonic structures display spatially-dependent surface plasmon excitation and sharp spectral resonances. Using these same templates, we also demonstrate a unique "in situ" template stripping process with a mechanical nano-manipulator in the FIB chamber, giving the capability to arbitrarily "copy," “cut,” and “paste” these patterned metallic nanostructures. These methods will allow the development of high-quality plasmonic devices with minimal sample-to-sample variation, ultrasmooth patterned metallic surfaces, and many degrees of design freedom.
5:15 PM - FF2.8
Highly Stretchable Organic Electronics: Real-Device Fabrication by Three-Dimensional Writing.
Ji Tae Kim 1 , Jaeyeon Pyo 1 , Jonghyun Rho 2 , Jong-Hyun Ahn 2 , Jung Ho Je 1 , G. Margaritondo 3
1 Materials science and engineering, Pohang University of Science and Technology, Pohang Korea (the Republic of), 2 School of Advanced Materials Science and Engineering, Sungkyunkwan University, Suwon Korea (the Republic of), 3 Faculté des Sciences de Base, Ecole Polytechnique Fédérale, Lausanne Switzerland
Show AbstractThe development of stretchable electronic devices is one of the most interesting challenges in modern technology (1). A substantial amount of research was focused on the realization of stretchable electrical interconnections. Recently, two innovative approaches to realize stretchable interconnections were developed, based on rubber-like elastomer/carbon nanotube composites (2) and wavy thin metals (3). Both strategies reach stretchability over 100 %, but are limited to passive interconnections – whereas stretchable devices require active components. Here, we demonstrate a variety of active electronic devices with extreme (>270%) stretchability using the organic conjugated polymer poly (3, 4 – ethylenedioxythiophene): poly (styrenesulfonate) (PEDOT:PSS).PEDOT:PSS was already used for electronics and optoelectronics devices such as transparent electrodes, electrochemical transistors and electrochromic systems. The patterning techniques included soft lithography and inkjet printing. However, these methods are limited to two-dimensional structures with tensile fracture strain < 5 % (4), insufficient for stretchable electronics. We overcame this obstacle by implementing a versatile our 3D technique (5, 6) based on accurately 3D guiding of a PEDOT:PSS meniscus by pulling a solution-filled micropipette. We thus obtained 3D microwires with controlled dimensions, site-specific positioning and tunable electrical transport properties. These structures included 3D microarches with excellent stretchability above 270 % and no compromise on the electrical characteristics. Such microarches were then successfully tested as components of different active microdevices such as electrochemical transistors and photo-switches operating under extreme stretching conditions. The impact of these successful tests goes well beyond these specific devices and opens the way to many different classes of stretchable microdevices based on organic materials.*Email: jhje@postech.ac.kr; giorgio.margaritondo@epfl.ch References(1) J. A. Rogers, T. Someya, Y. Huang, Science 327, 1603 (2010).(2) K. -Y. Chun et al., Nature Nanotech. 5, 853 (2010).(3) B. Y. Ahn et al., Science 323, 1590 (2009).(4) U. Lang, J. Dual, Key Eng. Mater. 345, 1189 (2007). (5) J. T. Kim et al., Adv. Mater. 23, 1968 (2011) [Inside front cover](6) J. T. Kim et al., Adv. Mater. (submitted)
5:30 PM - FF2.9
Fabrication of Metallic Nanocomponents by Forging of Ni3Al-Nanoparticles.
Andreas Landefeld 1 , Joachim Roesler 1
1 Technische Universität Braunschweig, Institute for Materials, Braunschweig, Lower Saxony, Germany
Show AbstractThe trend to manufacture size reduced components at the micro- and nanoscale is obvious and becomes more and more state of the art in designing actuators, sensors and chips. In recent years, nanoscale fabrication has developed considerably, but the fabrication of freestanding nanosize components is still a great challenge. The fabrication of metallic nanocomponents utilizing three basic steps is demonstrated here. First, metallic alloys are used as factories to produce a metallic raw stock of nano-objects/nanoparticles in large numbers. These objects are then isolated from the powder containing thousands of such objects inside a scanning electron microscope using manipulators, and placed on a micro-anvil or a die. Finally, the shape of the individual nano-object is changed by nanoforging using a microhammer to get specific geometries such as discs and more complex components such as gears and wheels in the near future. The almost cubic particles are essentially defect-free, therefore, provide very high strength (σ>2500 MPa) in combination with excellent formability (|φ|>1,6). There are two approaches for forming these small particles. Upset forging is used to forge small discs (height<100 nm) and to shape the nanoparticle in specific areas. Press forging into nano-dies is used to forge more complex structures. In this way free-standing, high-strength, metallic nano-objects may be shaped into components with dimensions in the 100 nm range. By assembling such nanocomponents, high-performance microsystems can be fabricated, which are truly in the micrometre scale (the size ratio of a system to its component is typically 10:1).
5:45 PM - FF2.10
Comparative Assessment of High Performance Nanostructured Wicks for Phase-Change Heatspreaders.
Shakti Chauhan 1 , Matthew Misner 1 , Tao Deng 1
1 , GE Global Research, Niskayuna, New York, United States
Show AbstractAdvanced thermal management solutions are required to keep up with the dramatic increase in power density in electronic/optoelectronic systems. Heatpipe-based thermal heatspreaders are devices that address this issue by utilizing two-phase heat transfer to achieve considerably greater effective thermal conductivities than conventional solid conduction heatspreaders (e.g. Copper). The porus wick structure in such devices typically drives not only the fluid transport but also the effectiveness of evaporation/condensation phenomena. In this paper, various wick fabrication methods are developed and compared via experimental testing. The methods are compared based on thermal characteristics of the wick and wick-substrate interface, effective pore size and porosity measurements, chemical stability in aqueous environments and the thermal performance of fully packaged heatpipes. In addition, trade-offs related to manufacturability, including uniformity of wick properties and scalability are assessed.
Symposium Organizers
Graham Cross Trinity College
Andre Schirmeisen University of Muenster
Armin Knoll IBM Research-Zurich
Marco Rolandi University of Washington
FF3: Scanning Probe Fabrication I
Session Chairs
Tuesday AM, November 29, 2011
Room 202 (Hynes)
9:30 AM - **FF3.1
Using Heatable AFM Probes for the Nanolithography of Graphene, Polymers, and Nanoparticles.
Paul Sheehan 1
1 U.S. Naval Research Laboratory, U.S. Naval Research Laboratory, Washington, District of Columbia, United States
Show AbstractHeatable AFM probes have proven to be a powerful means of shaping advanced materials on the nanometer scale. We have used these probes in two ways—as a stylus for directly writing material [1,2] or as a heater to react small regions of existing films [3]. When used for deposition, the heat from the probe regulates the viscosity of an ink coated on its surface, a technique we call thermal Dip Pen Nanolithography (tDPN). Control over writing is exceptional—deposition may be turned on or off and the deposition rate easily changed without breaking surface contact. Moreover, the technique may be performed in UHV and is compatible with standard CMOS processing. tDPN has been successful at depositing metal, polymers, semiconducting and magnetic nanoparticles, quantum dots, etc. at speeds up to 200 µm/s. Importantly, the ability to shear and anneal the deposited material can engender new properties not present in the bulk such as conduction anisotropy in conducting polymers or to force alignment of nanoparticles into rows narrower than 10 nm.The heatable probes can also focus heat to localize chemical reactions. Of recent interest has been using this heat to convert chemically-modified graphenes back to pristine graphene. For example, the heatable probe can directly write graphene nanoribbons by locally reducing graphene oxide back to graphene. The reduced GO nanostructures show an increase in conductivity up to four orders of magnitude as compared to pristine GO. No sign of tip wear or sample tearing was observed. Variably conductive nanoribbons with dimensions down to ~12 nm have been produced in oxidized graphene films in a single step that is clean, rapid and reliable. The method is fast, applies both to conducting and insulating substrates, and is reproducible.[1] Nano Letters (2010) 1: 129[2] Soft Matter (2008) 4:1844–1847[3] Science (2010) 328:1373
10:00 AM - FF3.2
Nanoscale Tunable Reduction of Graphene Oxide.
Elisa Riedo 1 , Paul Sheehan 2 , Debin Wang 1 , William King 2 , Walt der Heer 1 , Claire Berger 1 , Seth Marder 1 , Suenne Kim 1
1 Physics, Georgia Tech, Atlanta, Georgia, United States, 2 , Naval Research Laboratory, Washington, District of Columbia, United States
Show AbstractGraphene’s high electronic mobility has been harnessed in devices such as transistors operating at gigahertz frequency; however, the zero band gap of graphene leads to high leakage currents in many applications. The reduced form of graphene oxide (GO) is an attractive alternative to graphene for producing large-scale flexible conductors and for creating devices that require an electronic gap. We present a tip-based thermochemical nanolithography (TCNL) method to control the extent of reduction of GO and pattern nanoscale regions of rGO within a GO sheet at speeds of several um/s. The relative increase in conductivity is as high as four orders of magnitude compared to pristine GO. GO was converted to rGO with a 100% yield in dozens of structures patterned on random locations in the GO film. No sign of tip wear or sample tearing was observed, indicating that the “carbon skeleton” is continuous across the GO/rGO junction. Variably conductive nanoribbons with dimensions down to 12 nanometers could be produced in oxidized epitaxial graphene films in a single step that is clean, rapid, and reliable.TCNL does not require any solvents or lithographic resists that could contaminate the sample. This is especially important because the electronic properties of graphene and graphene oxide vary strongly with surface doping. Fabrication of graphene-based transistors by TCNL will be demonstrated.References:Z. Wei, D. Wang, S. Kim, S.-Y., Kim, C. Berger, Y. Hu, A. R. Laracuente, S. R. Marder, W. P. King, W. A. de Heer, P. E. Sheehan, E. Riedo, Science, 328, 1373 (2010).R. Szoszkiewicz, T. Okada, S. C. Jones, T.-D. Li, W. P. King, S. R. Marder, and E. Riedo, Nano Lett. 7, 1064 (2007).D. Wang, T. Okada, R. Szoszkiewicz, S. C. Jones, M. Lucas, J. Lee, W. P. King, S. R. Marder and E. Riedo, Applied Physics Letters 91, 243104 (2007).D. Wang, V. K. Kodali, W. D. Underwood, J. Jarvholm, T. Okada, S. C. Jones, M. Rumi, Z. Dai, W. P. King, S. R. Marder, J. E. Curtis, E. Riedo, Advanced Functional Materials, 19, 3696 (2009).D. Wang, S. Kim, W. D. Underwood, W. P. King, C. L. Henderson, S. R. Marder, E. Riedo, Applied Physics Letters, 95, 233108 (2009)
10:15 AM - **FF3.3
Direct Write 3-Dimensional Nanopatterning Using Probes.
Urs Duerig 1 , Felix Holzner 1 , Philip Paul 1 , Michel Despont 1 , Armin Knoll 1
1 , IBM Reserach - Zurich, Rueschlikon Switzerland
Show AbstractA novel probe patterning method based on the local evaporation of organic resist materials been developed at the IBM Research Laboratory in Zurich [1-3]. A three dimensional relief pattern is written directly into the resist without the need for a development step. The technology has a number of unique attributes: High resolution patterning capability compatible with the requirements of future transistor technology; high patterning speed comparable to high resolution electron beam lithography, and direct writing of three dimensional relief structures with nm precision, which is not possible with any other technology. The resist material is decomposed and evaporated locally pixel by pixel using a hot tip. This can be done with high speed (500000 pixels per second, 20 mm/s scan speed), high accuracy (<10 nm) and excellent control of the patterning depth. Our scanning-probe-based patterning method also allows high-resolution imaging and hence accurate in-situ detection of features on the target substrate prior to the patterning process. For example, the natural roughness of the resist surface provides a unique marker for high-resolution stitching enabling the seamless writing of arbitrarily large fields. An other important aspect for lithographic applications is the ability to transfer the written patterns into Si using standard technology. We showed that 40x overall depth amplification can be achieved using an intermediate hard mask transfer step. The control of the third dimension in patterning is a novel feature which has been rarely explored in nano-technology. By combining our patterning technology with reactive ion etching, we demonstrated multilevel bit data recording at 99Gbit/in2 density in a poly-Si/SiO2 carrier for ultra-long retention archival data preservation. The relief structures written in the resist can also be used as template for the guided assembly of nano-particles. The interesting feature is that the temperature sensitive resist can be easily removed after the assembly step, and as a result, the particles are directly transferred to the target substrate preserving their position and orientation as demonstrated in an assembly experiment using 75 nm long and 25 nm diameter Au nano-rods. Combining in-situ imaging with the removable template strategy allows the precise registry of the assembled particles with functional elements on the target substrate, which is a unique asset for future applications. [1] David Pires, James L. Hedrick, Anuja De Silva, Jane Frommer, Bernd Gotsmann, Heiko Wolf, Michel Despont, Urs Duerig, and Armin W. Knoll, Science 328, 732-735 (7 May 2010)[2] Armin W. Knoll, David Pires, Olivier Coulembier, Philippe Dubois, James L. Hedrick, Jane Frommer, Urs Duerig, Adv. Materials 22, 3361-3365 (2010)[3] Philip C. Paul, ArminW. Knoll, Felix Holzner, Michel Despont andUrs Duerig, Nanotechnology 22, 275306 (2011).
10:45 AM - FF3.4
Thermochemical Nanolithography of Arbitrary-Shaped Ferroelectric Structures on Plastic, Glass and Silicon Substrates.
Suenne Kim 1 , Yaser Bastani 1 , Haidong Lu 2 , William King 3 , Seth Marder 1 , Kenneth Sandhage 1 , Alexei Gruverman 2 , Elisa Riedo 1 , Nazanin Bassiri-Gharb 1
1 , Georgia Institute of Technilogy, Atlanta, Georgia, United States, 2 , University of Nebraska-Lincoln, Lincoln, Nebraska, United States, 3 , University of Illinois Urbana-Champaign, Urbana, Illinois, United States
Show AbstractFerroelectric oxides are versatile smart materials that are attractive for a variety of nanometer scale applications owing to their switchable spontaneous polarization, pyroelectricity, and piezoelectricity (with high piezoelectric coefficients). However, the high processing temperatures required for their synthesis are mostly incompatible with other on-chip components, and the properties of these materials are often found to depend on the nanofabrication procedures. We report the creation of Pb(Zr_0.52Ti_0.48)O_3 (PZT) and PbTiO_3 (PTO) ferroelectric nanostructures in various shapes on platinized and plain plastic (Kapton) to silicon and soda-lime glass substrates, by mask-less thermochemical nanolithography (TCNL). An atomic force microscope (AFM) thermal tip is used as a local heat source to induce nanoscale crystallization of sol-gel precursor films. Ferroelectric lines with widths as narrow as 30 nm, spheres with diameters as small as 10 nm, and densities as high as 213 Gb/in^2 have been produced.
11:30 AM - FF3.5
Nanoscale Dislocation Patterning of Cubic Semiconductors by Atomic Force Microscopy.
Rodrigo Prioli 1 , Paula Caldas 1 , Clara Almeida 2 , Jingyi Huang 3 , Fernando Ponce 3
1 Physics, PUC-Rio, Rio de Janeiro Brazil, 2 Materials Division, INMETRO, Rio de Janeiro, Rio de Janeiro, Brazil, 3 Physics, Arizona State University, Tempe, Arizona, United States
Show AbstractThe development of nanopositioning systems allows the precise placing of atomic force microscopy tips, and the controlled application of forces of few nano Newtons on areas with dimensions close to the atomic scale. The tip displacement can be measured with nanometer precision while the force between the tip and the sample is varied. The pressure applied by the instrument tip may cause the generation of dislocations at an atomic scale by the slip of specific crystal planes in nanometer-scale volumes. The dislocations introduced at low forces are usually highly localized bellow the deformed area, opening the possibility of nanoscale lithography where the nature of a crystalline substrate is modified by the precise introduction of dislocations at specific surface sites. Dislocation patterns have been produced by atomic force microscopy scratching of (100) InP crystals along specific crystallographic directions with forces ranging from 7 uN to 120 uN. The mechanical deformation process was studied by atomic force microscopy and transmission electron microscopy. For a given applied force, deeper plastic flow has been observed in the <110> case than in the <100> case. Under increasing applied forces, plastic flow was first observed at 15 uN for <110>, and at 30 uN for <100>. The crystal deformation during a scratch event has been observed to consist of three stages: (a) surface conformation to the shape of the AFM tip during the early stages of the process, and it is associated with slip at the nanoscale with the formation of an inverted triangular region with high dislocation density; followed by (b) a sudden displacement (pop-in) that signals the beginning of downward slip at the bulk scale; and (c) for sufficiently large forces, recovery of the bulk elastic strain by upward slip (pop-up). The <110> scratch direction is aligned along the {111} slip planes, and yields at lower applied forces than in the <100> case. Scratching along the <110> direction generates anisotropic butterfly-like structures with mostly screw dislocations indicating rotational motion in the vicinity of the advancing tip. For <100> directions, the dislocations do not propagate far from the surface, possibly due to interlocking between dislocations on different slip planes. The influence of melting introduced by frictional heat has also been observed.
11:45 AM - FF3.6
Theoretical Study of Atomic Manipulation on Metals.
Martin Ondracek 1 , Zdenka Chromcova 1 , Cesar Gonzalez 2 1 , Pavel Jelinek 1
1 Department of Thin Films and Nanostrucures, Institute of Physics, AS CR, Prague Czechia, 2 , Instituto Ciencia de Materiales de Madrid, Madrid Spain
Show AbstractThe recent progress of the non-contact atomic force microscopy (nc-AFM) technique has enabled controlled manipulation of single atoms on various types of surfaces [1]. A potential energy landscape of the tip-sample interaction can be constructed from force maps recorded during the manipulation process. Moreover, both vertical and lateral forces necessary to move an atom can be directly estimated [2]. Surprisingly, the experimental findings on metal surfaces [2] show that only the lateral force component plays the decisive role in moving a single surface atom. This observation contrasts with the observations made previously on a semiconductor surface [3].We have carried out extensive theoretical simulations to get more insight into the manipulation of a single atom on a closed-packed metal surface, in particular the Cu(111) surface. We combine the total energy DFT calculations with classical Molecular Dynamics using Force Field potentials. We have investigated the conditions required for moving a Cu adatom on the Cu(111) surface with the AFM probe in terms of the atomic structure on the AFM tip termination, the distance of the tip from the surface, and the force acting between the tip and the adatom. We will discuss the implications for the mechanism of lateral atomic manipulation that result from using either a static STM mode at constant height or an oscillating AFM mode. References:[1] O. Custance et al., Nature Nanotechnology 4 (2009) 803.[2] M. Ternes et al., Science 319 (2008) 1066.[3] Y. Sugimoto et al., Phys. Rev. Let. 98 (2007) 106104.
12:00 PM - **FF3.7
New Technologies through Atom-Scale Crafting: New Microscopes and a Route Beyond the Semiconductor Roadmap to Ultra-Low Power Silicon Electronics.
Robert Wolkow 1
1 Physics, University Alberta, Edmonton, Alberta, Canada
Show AbstractThree examples of atom-scale crafting will be given. One involves making the ultimate needle – a sharp tip that terminates in one Tungsten atom, is very robust due to a covalent crust of Tungsten Nitride, and can be rebuilt, in situ, exactly as before. This tip is an important scan probe for atom scale fabrication, it is an extraordinary electron source, and it is the best known ion source for a new generation of scanning ion microscopes. Such ion sources will in turn serve as a new atom scale writing tool that is possibly more desirable than e-beam in some applications. Yet another variant, operated with Neon, may compete with the familiar liquid Gallium source FIB (focussed ion beam) for nano-scale machining.A home-made multi-probe, scanned probe microscope will be briefly described also. I will focus on the kinds of characterizations made possible by this new tool. Several similar commercial instruments are now available making such measurements more widely accessible. For example, atom-scale potentiometry can now be done with extreme sensitivity. Also, proto-devices can be directly probed without need for a fully lithographically connected structure.Finally I will mention a path toward a new atomic electronics technology we hope to soon commercialize. This silicon based proto-technology addresses the most pressing short coming of today’s CMOS – that is uncontrollable power density. Our new approach, an extension of that created by Craig Lent more than a decade ago, employs quantum-dot cellular automata to achieve extremely low power consumption. Larger ensembles of silicon dangling bonds can be viewed as quantum dot collectives, or artificial molecules. This beautiful and adaptable construct has long been viewed as a kind of ideal that is unfortunately beyond practical realization because of various problems – fabrication and low temperature requirements being foremost among those. We intend to make a functioning, room temperature, atomic silicon-based quantum dot cellular automata device. Demonstrations in this presentation will be limited to the basic building block – the 4 dot cell – and the biasing of that cell. We will as well describe some finer details of our developing characterization of such entities.
12:30 PM - FF3.8
Controlling Pattern Formation in Ferroelectric Nanolithography to Enable Multi Component Functional Device Properties.
David Conklin 1 , Sanjini Nanayakkara 1 , Tae-Hong Park 2 , Michael Therien 3 , Dawn Bonnell 1
1 MSE, University of Pennsylvania, Philadelphia, Pennsylvania, United States, 2 Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania, United States, 3 Chemistry, Duke University, Durham, North Carolina, United States
Show AbstractIn spite of novel lithographic processes that enable new approaches to fabricating materials, directed assembly of multi-component hybrid devices remains a challenge. Ferroelectric nanolithography has the potential to overcome these challenges. This process combines polarization stamping or probe patterning with directed assembly. It exploits polarization dependent surface interactions to pattern nanoparticles, but the factors that control the particle size and distribution were not sufficiently well understood to produce hybrid nanostructures. Here the effects of photon energy, photon flux, and polarization vector orientation on ferroelectric domain specific photoreactions are quantified, leading to an understanding of the nanoparticle deposition mechanism. This understanding enables the size and separation of nanoparticles to be controlled, such that molecules can be linked to patterned nanoparticle arrays in order to form functional hybrid nanostructures. An electro- optical device was assembled that demonstrated enhanced photo conductivity due to plasmon interactions. These results define a pathway for Ferroelectric Nanolithography to be used to pattern a wide range of multi-component structures with applications ranging from optoelectronics to energy harvesting
12:45 PM - FF3.9
Scanning Probe Nanostructure Direct-Write: From Serial to Parallel Patterning.
Stephanie Vasko 1 2 , Adnan Kapetanovic 1 , Michael Brasino 1 , Vamsi Talla 3 , Hideki Sato 1 , Marco Rolandi 1
1 Materials Science and Engineering, University of Washington, Seattle, Washington, United States, 2 Chemistry, University of Washington, Seattle, Washington, United States, 3 Electrical Engineering, University of Washington, Seattle, Washington, United States
Show AbstractLarge-scale throughput of nanoscale heterostructures is fundamental for future semiconductor devices. We have developed an approach to nanostructure direct-write that exploits the tip of an atomic force microscope (AFM) to control the size, shape, and composition of nanostructures. The biased probe of an AFM reacts diphenylsilane or diphenylgermane to direct-write carbon-free (SIMS, x-ray PEEM) Si and Ge nano and heterostructures. Proof-of-concept SiGe nanostructures have also been demonstrated. The underlying chemical reactions occurring in the direct write process and deposition mechanism will be discussed. The general nature of the high field chemical reaction is demonstrated through parallel patterning via a flexible stamp approach. Efforts on expanding parallel printing mass manufacture by adapting this process to 4” mask aligner technology will be discussed. This high field approach to deposition of organometallic precursors could offer a low-cost, high throughput alternative for optical, electronic, and photovoltaic applications.
FF4: Fluidic and Directed Self Assembly Techniques
Session Chairs
Tuesday PM, November 29, 2011
Room 202 (Hynes)
2:30 PM - FF4.1
Toward Wafer-Scale Patterning of Freestanding Intermetallic Nanowires.
Romaneh Jalilian 1 , Sreenath Arva 2 , Davood Askari 3 1 , Jeremy Rathfon 2 , Jose Rivera 1 , Robert Cohn 2 , Mehdi Yazdanpanah 1
1 , NaugaNeedles , Louisville, Kentucky, United States, 2 ElectroOptics Research Institute and Nanotechnology Center, University of Louisville, Louisville, Kentucky, United States, 3 Department of Engineering, University of Texas at Brownsville, Brownsville, Texas, United States
Show AbstractIndividual metal alloy nanowires of constant diameter and high aspect ratio have previously been self-assembled at selected locations on atomic force microscope (AFM) probes by the method reported in Yazdanpanah et al (2005 J. Appl. Phys. 98 073510). This process relies on the room temperature crystallization of an ordered phase of silver–gallium. A parallel version of this method has been implemented in which a substrate, either an array of micromachined tips (similar to tips on AFM probes) or a lithographically patterned planar substrate, is brought into contact with a continuous, nearly planar film of melted gallium. In several runs, freestanding wires are fabricated with diameters of 40–400 nm, lengths of 4–80 μm, growth rates of 80–170 nm s−1 and, most significantly, with yields of up to 97% in an array of 422 growth sites. These results demonstrate the feasibility of developing a batch manufacturing process for the decoration of wafers of AFM tips and other structures with selectively patterned freestanding nanowires.
2:45 PM - FF4.2
Determining Metallicity of Nanowires via Their Mechanical Motions in Electric Fields.
Xiaobin Xu 1 , Kwanoh Kim 1 , Donglei Fan 1
1 Mechanical Engineering, Univerisity of Texas at Austin, Austin, Texas, United States
Show AbstractRecently intensive interest has been focused on nanowires due to their unique electrical properties. When measuring the electrical properties, one has to make electric contacts to the nanowires, which requires ardous fabrication process. In this work, we report an uncontact and undestructive appraoch to determine metallicity of nanowires via their mechanical motions in suspension in electric fields. Metallic (e.g. Au) and non-metallic nanwires (e.g. SiO2) have been rotated at AC electric fields of a few hundred kHz to 1 MHz. The nanoiwres exhibit distinctive rotation directions, e.g. clockwise for metallic nanowires and counter clockwise for non-metallic nanowires. Study of the physics relates the rotation direction to the electrical properties of nanowires. This research can be readily used to distinguish metallic/non-metallic nanowires.
3:00 PM - **FF4.3
Mechanical Aspects of Particle Self-Assembly from Liquid Menisci.
Philip Born 1 , Tobias Kraus 1
1 Structure Formation Group, Leibniz Institute for New Materials (INM), Saarbrücken Germany
Show AbstractParticles in a size range between 1 μm and 50 nm can be assembled from their dispersion by moving its meniscus over a substrate. Depending on the geometry and the substrate, uniform dense layers or sparse patterns of particles are deposited.A meniscus that moves over a patterned substrate at a non-wetting contact angle can selectively deposit particles on patterned regions (“capillary assembly”) [1]. The yield depends on the local particle concentration. Assembly with reasonable efficiency thus requires an “accumulation zone” that is enriched with particles. It is out of this volume that particles are deposited on the patterned sites of the template.Assembly from a wetting liquid yields continuous particle films (“convective assembly”) [2]. Particles are transported into a thin liquid film by convection, where they assemble into a densely packed layer. The assembly process relies on forces exerted by the liquid flow. It is strongly affected by the shape of the meniscus that confines the particles. We show that the mechanical behavior of the meniscus governs the attainable quality of assembled films [3].We will discuss the effects of fluid motion, gas-liquid interfaces and particle interactions on the outcome of these assembly processes. The results guide the choice of assembly setup geometries, process variables and particle types for high-quality particle assembly at high yields.[1] Kraus, Malaquin, Schmid, Riess, Spencer, and Wolf, Nature Nanotechnology 2007, 2, 570-576[2] Malaquin, Kraus, Schmid, Delamarche, and Wolf, Langmuir 2007, 23, 11513-11521[3] Born, Blum, Munoz, and Kraus, Langmuir 2011 ASAP, DOI: 10.1021/la2006138
3:30 PM - FF4.4
Nanoparticle Stripes, Ribbons and Grids via Flexible-Blade Flow Coating.
Dong Yun Lee 1 , Jonathan Pham 1 , Jimmy Lawrence 1 , Hyun Suk Kim 1 , Cheol Hee Lee 1 , Yujie Liu 1 , Cassandra Parkos 2 , Todd Emrick 1 , Alfred Crosby 1
1 Polymer Science & Engineering, University of Massachusetts Amherst, Amherst, Massachusetts, United States, 2 Mechanical Engineering & Materials Science, UC Berkeley College of Engineering, Berkeley, California, United States
Show AbstractWe present the controlled formation of nanoparticle stripe patterns on underlying substrates by flexible-blade flow coating. This technique exploits the combination of convective flow of highly confined nanoparticle solutions and programmed translation of a substrate to fabricate nanoparticle-polymer line assemblies. We achieve nanostripe dimensions of width below 300 nm, thickness of a single nanoparticle (~ 6 nm), and continuous length exceeding 5 cm. This multi-lengthscale control is facilitated by the use of a flexible blade, which allows capillary forces to self-regulate the uniformity of convective flow processes. We exploit solvent mixture dynamics and nanoparticle chemistry to enhance intra-assembly particle packing, leading to novel assembly properties including conductivity and free-standing mechanical flexibility and strength. This facile technique and the novel materials that are fabricated open up a new paradigm for integration of nanoscale patterns over large areas for various applications.
3:45 PM - FF4.5
High-Rate Electro-Fluidic Directed Assembly of Nanoparticles and Nanotubes.
Asli Sirman 1 , Cihan Yilmaz 1 , Jun Huang 1 , Sivasubramanian Somu 1 , Ahmed Busnaina 1
1 Mechanical and Industrial Engineering, NSF Nanoscale Science and Engineering Center for High-rate Nanomanufacturing , Boston, Massachusetts, United States
Show AbstractDirected assembly of nanoelements has been used to fabricate devices for diverse applications. The challenge in using such techniques consists of developing highly scalable, high-rate (fast) assembly techniques for placing nanoelements precisely on either conductive or insulating surfaces. Fluidic assembly, which employs the interfacial capillary forces, is a method used for assembling nanoelements onto many substrates (regardless of conductivity). However, fluidic assembly is diffusion limited and therefore, is a very slow process. During the fluidic assembly, nanoelement migration toward the substrate is only driven by the concentration gradient between the assembly region and bulk solution. On the other hand, electric field induced assembly techniques (such as electrophoresis) are very fast, however, they need a conductive surface and the assembly has to occur on a conductive substrate. This is not desirable for many electronics applications. Here, we introduce a new, high-rate electro-fluidic assembly technique that enables directed assembly on any type of insulating surfaces. The significance of this technique is that the assembly process is 100 times faster than fluidic assembly (the only technique used today on insulating surfaces). For example, fluidic assembly on a 3-inch wafer takes 25 hours; however, the presented method takes only 15 minutes to obtain fully assembled structures. In the electro-fluidic assembly process, a conductive film is used beneath the insulating substrate or film and field is applied through that conducting layer. Under the influence of the applied field, nanoelements move towards the template increasing the nanoelement concentration near the patterned template. A PECVD deposited silicon oxide layer on the top of a gold conductive film acts as the insulating layer. To achieve site-specific assembly a patterned PMMA layer is applied on the top of the insulating layer. A dip coater is used to provide precise and constant pulling speed of the template from the solution. Since the presence of an insulating (dielectric) layer inherently reduces the strength of the applied electric field, we increased the applied potential to effecti