Symposium Organizers
Francesco Stellacci Massachusetts Institute of Technology
Joseph W. Perry Georgia Institute of Technology
Gregory S. Herman Hewlett-Packard Company
Rabindra Nath Das Endicott Interconnect Technologies
T1: Carbon Nanotubes and Inorganic Nanowires
Session Chairs
Gregory Herman
Carl Thompson
Tuesday PM, April 18, 2006
Room 2004 (Moscone West)
9:30 AM - **T1.1
Carbon Nanotube Electronics and Optoelectronics
Phaedon Avouris 1
1 , IBM T.J. Watson Research Center, Yorktown Heights, New York, United States
Show AbstractCarbon nanotubes (CNTs) have properties that make them ideal for applications in both nano- and opto-electronics. Although a variety of different electronic devices based on CNTs have been demonstrated, most of the emphasis has been on CNT field-effect transistors (CNTFETs). In these a single semiconducting CNT replaces silicon as the transistor “channel.” The resulting devices have in many respects characteristics superior to conventional devices. However, they also pose a set of new challenges. These include understanding the new 1D transport physics, reducing the influence of Schottky barriers at CNT-metal contacts and eliminating the ambipolar behavior of vertically-scaled CNTFETs. I will discuss how most of these problems can be eliminated to produce high performance single nanotube devices and multi-component circuits. We have used ambipolar (a-) CNTFETs to simultaneously inject electrons and holes with a fraction of these recombining radiatively to produce an electrically-excited, single nanotube molecule light source. Unlike conventional p-n diodes, a-CNTFETs are not doped and there is no fixed p-n interface. Thus, the emitting region can be translated at will along a CNTFET channel by varying the gate voltage. We have found that much stronger (1000x) local electroluminescence spots are also generated at defects or inhomogeneities that introduce potential drops. The emission is the result of intra-molecular impact excitation of electron-hole pairs by the accelerated (“hot”) carriers. Localized electroluminescence provides a high brightness IR source and a novel probe of defects, charging, and other otherwise difficult to observe inhomogeneities.
10:00 AM - T1.2
Self-Assembly for Nanomanufacturing of Large-Scale Integrated Carbon Nanotube Circuits
Minbaek Lee 1 , Jiwoon Im 1 , Juwan Kang 1 , Seunghun Hong 1
1 School of Physics, Seoul National University, Seoul Korea (the Republic of)
Show AbstractElectronic circuits based on carbon nanotubes (CNTs) have been drawing tremendous attention as a generation of new functional devices. However, a lack of reliable nanomanufacturing method for such circuits has been holding back their practical applications. One promising nanomanufacturing method for CNT-based circuits can be “surface-programmed assembly” process (Nature 425, 36 (2003)), where functional molecular monolayer on the substrate guide the ‘selective assembly’ and ‘precision alignment’ of CNTs on the substrate in the solution. Significantly, since this process does not require any high-temperature processing steps, it can be applied to virtually any substrates. Using this method, we successfully demonstrated assembly of large-scale integrated carbon nanotube circuits on various substrates including Au, SiO2, Al, glass, polymer, etc. Furthermore, we fabricated 64k CNT junction arrays and the array of CNT-based FETs with top-gates. This surface-guided nanomanufacturing process can remove a major bottleneck in manufacturing of CNT-based devices and open up a new possibility in CNT-based electronics. The possible impacts and future prospects of this process also will be discussed.
10:15 AM - T1.3
Biological Assembly of Functional Nanostructures
Cengiz Ozkan 1
1 Mechanical Engineering, University of California at Riverside, Riverside, California, United States
Show AbstractConventional device fabrication strategies must be augmented by new techniques including self assembly methods in order to truly take advantage of the quantum nature of novel nanoscale electronic devices and systems and permit the use of these properties for “real” applications in a larger system > 10 nm and < 1000 nm). In this talk, I will first describe a novel technique for the fabrication of nano-assemblies of carbon nanotubes (CNT) and quantum dots (QD) -formation of CNT-QD conjugates-. Heterojunctions of QD’s and MWCNT’s could become better alternatives for the synthesis of nanoscale devices which would preserve the electronic properties of MWCNT’s compared to configurations that depend on the bending or overlapping of CNT’s. Such configurations could be useful for the bottom-up assembly of nanoscale circuits or as drop-in technologies for the existing device platforms. I will discuss strategies to combine nanoscale building blocks with biomimetic structuring schemes employing DNA recognition to encode the desired structure at various levels. In addition, I will talk about the electrical properties of the bio-inorganic interfaces at the nanoscale. Detailed chemical and physical characterization of the heterojunctions have been conducted using Fourier transform infrared spectroscopy, transmission electron microscopy and Raman spectroscopy. Finally, I will discuss the applications of carbon nanotubes for biological applications including encapsulation and mass transport of DNA. Potential applications of our studies include the fabrication of novel electronic and spintronic devices and biosensors.
10:30 AM - T1.4
Producing Catalytically Active Nanostructures via Solution or Thin Film Self-assembly of Block Copolymers for Carbon Nanotube and Silicon Nanowire Growth.
Jennifer Lu 1 , Mark Hueschen 1 , Thomas Kopley 1 , Ian Manners 3 , Mitch Winnik 3 , David Rider 3 , Qian Cheng 2 , Sungsoo Yi 1 , Jie Liu 2 , Dave Dutton 1
1 , Agilent Technologies, Palo Alto, CA, California, United States, 3 , The University of Toronto, Toronto, British Columbia, Canada, 2 , Duke University, Durham, North Carolina, United States
Show AbstractBlock copolymers, a class of self-assembling macromolecules, can be spontaneously self-organized into well-ordered morphologies on the nanometer scale. In this talk, fabrication of nanostructures composed of transition metals such as Fe, Co, Ni, and Au using block copolymer templates will be discussed. Metal-containing nanostructures with controlled size and periodicity have been fabricated. These catalytically active nanostructures promote the controllable synthesis of carbon nanotubes and silicon nanowires. Carbon nanotubes with diameters less than 1 nm and silicon nanowires with diameters less than 10nm have been produced. Moreover, it has been established that the diameter of CNTs can be tuned by adjusting block copolymer chain lengths. Uniformly distributed carbon nanotubes and silicon nanowires have been successfully synthesized. By combining the self-assembly technique with top-down photolithography, selective growth of carbon nanotubes and silicon nanowires on a surface or suspended across a trench has been demonstrated. The block copolymer template approach provides a rational synthetic method of generating catalytically active nanostructures on a wafer format using existing semiconductor methodologies and thus offers greatly enhanced manufacturability for large scale fabrication of carbon nanotube-based devices.
10:45 AM - T1.5
Top-down On-wire Structure and Device Fabrication using In-situ Nanomachining.
Xiaodong Li 1 , Xinnan Wang 1 , Patrick Nardi 1 , Hongsheng Gao 1 , Qihua Xiong 2 , Peter Eklund 2 , Catherine Murphy 3 , K. Caswell 3 , Chang-Wook Baek 4 , Jong-Man Kim 4 , Yong-Kweon Kim 4
1 Department of Mechanical Engineering, University of South Carolina, Columbia, South Carolina, United States, 2 Department of Physics, Pennsylvania State University, University Park, Pennsylvania, United States, 3 Department of Chemistry and Biochemistry, University of South Carolina, Columbia, South Carolina, United States, 4 School of Electrical Engineering and Computer Science, Seoul National University, Seoul Korea (the Republic of)
Show AbstractWe demonstrate the potential of a new tool for the fabrication of nanoscale structures and devices. A nanoindenter integrated with an atomic force microscope is shown to be a powerful machine tool for cutting precise length nanowires/nanobelts and for manipulating the shortened wires/belts. We also demonstrate its utility in cutting grooves and fabricating dents (or periodic arrays of dents) in silver and gold nanowires and ZnS nanobelts. This approach permits the direct mechanical machining of nanostructures nanodevices that are supported on a substrate without the inherent complications of e-beam or photolithography.
11:30 AM - T1.6
Alignment of Nanowire Electrodes for Fabricating Nanoscale Devices.
Shuhong Liu 1 , Zhenan Bao 2
1 Material Science and Engineering, Stanford University, Stanford, California, United States, 2 Chemical Engineering, Stanford University, Stanford, California, United States
Show AbstractConsiderable efforts have been placed on searching for alternatives to conventional silicon electronics in recent years. Present photolithographic techniques grow exponentially more expensive with decreasing feature size, and may never reach the dimensions required for new technologies. One dimensional nanostructures, such as nanowires, represent promising building blocks for assembly of nanodevices that could overcome the economic and fundamental limitations of lithography-based fabrication. In our work, we develop a new “bottom up” approach that could assemble nanowires into aligned arrays. Combined with selective chemical etching, patterned electrode gaps ranging from 20nm to a few micrometers are demonstrated.Metallic nanowires with multicomponents are prepared through sequential electrochemical deposition of different metal components into porous alumina template and are derivatized with using self-assembled monolayers. Alignment of nanowires are studied by controlling several parameters, such as surface chemistry of the bottom electrode contacting the nanowires, surface topography, and flow conditions. Several approaches such as microcontact printing and etching are employed here.After the nanowires are aligned, electrode gaps are formed through selective chemical etching of the center Ag segment of the nanowires, and organic transistor devices are fabricated by depositing organic semiconductors in the gaps.
11:45 AM - T1.7
Bonding of Nanowire Assemblies Using Adhesives and Solder
Zhiyong Gu 1 , Hongke Ye 1 , David Gracias 1 2
1 Chemical and Biomolecular Engineering, Johns Hopkins University, Baltimore, Maryland, United States, 2 Chemistry, Johns Hopkins University, Baltimore, Maryland, United States
Show AbstractIn recent years, the extreme miniaturization has pushed the capabilities of conventional top-down microfabrication to its limits. One promising nanomanufacturing strategy is to direct the assembly of nanoscale components from the bottom-up. Directed assembly is inspired by biological self-assembly; nature is able to mass produce a wide variety of complex 2D and 3D structures with a wide range of sizes. The nanocomponents used in directed assembly are fabricated using a variety of methods including CVD, electrodeposition in templates and molecule templated growth. The nanocomponents are engineered so that they are capable of interacting with one another, to form organized integrated structures. The complexity of the assembled structure formed can be increased by utilizing complex components with different recognition sites that facilitate a variety of interactions of different magnitudes. Several interaction forces have been used to direct assembly of nanocomponents including the use of molecular recognition, electrostatic forces, dielectrophoresis, magnetic forces, or surface tension based forces.Although the aforementioned strategies have been very successful in the fabrication of integrated structures, in many cases, the structures formed are not well bonded to one another, i.e. the assemblies although held together in the fluidic medium in which they are assembled, fall apart when taken out of the medium or during mild sonication. Additionally, in directed assembly between rigid nanocomponents, the strength and the extent of binding is proportional to the overlap area at the binding site between components. Any local roughness of the components reduces the effective binding contact area due to asperities, and consequently decreases the strength and extent of binding. Hence, assemblies often consist of only a few bonded nanocomponents, and large scale integration is not possible. It should be noted that in biological self-assembly, most of the components utilized in the assemblies are soft and deformable which allows the mating surfaces to conform to one another resulting in large contact areas for optimum binding. We demonstrate the fabrication of 2D and 3D structures composed of nanowires that were bonded to each other and to substrates using a curable adhesive or solder. In our strategy, liquid layers of an organic adhesive or molten solder on specific regions of the nanowire facilitated binding between components by minimization of interfacial free energy (surface tension driven assembly). The adhesive and solder were subsequently hardened by curing (polymerization) and cooling respectively. In the case of the adhesive, the 2D and 3D structures formed survived mild sonication and could be taken out of the fluidic medium without disruption. In the case of solder it was possible to form ohmic low resistance contacts that points to the feasibility of using these joints as nanoscale electrical contacts.
12:00 PM - T1.8
Electric Field-directed Assembly of Nanowire Arrays.
Mingwei Li 1 , James Sioss 2 , Christine Keating 2 , Theresa Mayer 1
1 Electrical Engineering, Pennsylvania State University, University Park, Pennsylvania, United States, 2 Chemistry, Pennsylvania State University, University Park, Pennsylvania, United States
Show Abstract12:15 PM - T1.9
DNA-Templated Assembly of Gold Nanowires.
Amro Satti 1 2 , Damian Aherne 1 2 , Donald Fitzmaurice 1 2
1 School of Chemistry and Chemical Biology, University College Dublin, Dublin Ireland, 2 Centre for Research on Adaptive Nanostructures and Nanodevices (CRANN), Trinity College Dublin, Dublin Ireland
Show AbstractReported is the use of DNA to template the assembly of gold nanowires from gold nanoparticles. The DNA template, specifically double-stranded calf thymus DNA, is initially deposited on a polystyrene coated silicon wafer substrate [1]. The above wafer is then exposed to an aqueous dispersion of positively charged gold nanoparticles (4 nm diameter) [2], which are selectively adsorbed at the negatively charged DNA template. The adsorbed nanoparticles are then enlarged and enjoined by electroless deposition [3], to form a continuous nanowire. Gold electrodes are then overlaid on the above nanowires using conventional lithographic techniques [1] and their electrical properties were measured.To date, this approach has been used to prepare gold nanowires up to 25 μm in length and between 25 and 300 nm in diameter. These nanowires exhibit resistivities of less than 10-7 Ωm, close to the value of reported for bulk polycrystalline gold wires [4]. These and related findings have implications for the design and assembly of next generation electronic devices. References: [1] O. Harnack, W. Ford, Z. Karipidou, A. Yasuda and J. Wessels; Proceedings of Foundations of Nanoscience: Self-Assembled Architectures and Devices; Snow Bird, Utah, USA, April 21-23, 2004.[2] F. Griffin and D. Fitzmaurice, Langmuir, 2004; manuscript submitted. [3] S. Hrapovic, Y. Liu, G. Enright, F. Bensebaa and J. H. T. Luong; Langmuir, 2003, 19, 3958 [4] A. Paskaleva and E. Atanassova; Solid-State Electronics, 1998, 42, 777
12:30 PM - **T1.10
Semiconductor Nanowires as Subwavelength Optical Elements for Photonics Integration
Peidong Yang 1
1 , Univ. Calif. Berkeley, Berkeley, California, United States
Show AbstractThe manipulation of optical energy in structures smaller than the wavelength of light is key to the development of integrated photonic devices for computing, communications and sensing. Wide band gap semiconductor nanostructures with near-cylindrical geometry and large dielectric constants exhibit two-dimensional ultraviolet and visible photonic confinement (i.e. waveguiding). Combined with optical gain, the waveguiding behavior facilitates highly directional lasing at room temperature in controlled-growth nanowires with suitable resonant feedback. The nanowire optical emission has been studied in detail using high-resolution optical microscopy. This concept of using well-cleaved nanowires as natural optical cavities may be extendable to many other different semiconductor systems. We have further explored the properties and functions of individual ultralong crystalline oxide nanoribbons that act as subwavelength optical waveguides and assess their applicability as nanoscale photonic elements. The length, flexibility and strength of these structures enable their manipulation on surfaces, including the optical linking of nanoribbon waveguides and other nanowire elements to form networks and device components. We have demonstrated the assembly of ribbon waveguides with nanowire light sources and detectors as a first step toward building nanowire photonic circuitry.
T2: Fabrication Methods
Session Chairs
Tuesday PM, April 18, 2006
Room 2004 (Moscone West)
2:30 PM - **T2.1
Photopolymerization and Metalization for Fabricating Functional Devices and Metamaterials.
Satoshi Kawata 1 2 , Takuo Tanaka 2 , Nobuyuki Takeyasu 2
1 Applied Physics, Osaka University, Suita, Osaka, Japan, 2 , RIKEN, Saitama Japan
Show AbstractWe present three-dimensional micro/nano-fabrication techniques to create new photonic and functional devices. We have demonstrated two-photon-induced photopolymerization for fabricating 3D micro/nano-structures [1, 2]. In this method, arbitrary three-dimensional polymer structures are fabricated by scanning tightly focused infrared femto-second laser in three dimensions. Recently, we extended this technique to fabricate functional micro devices including photonic band-gap crystals [3] and movable micro-springs. The shrinkage of polymer during polymerization is utilized to reduce the structure size beyond the diffraction limit of light [4]. A micro-lens array with 2500 lenses is used to produce a mass of structures in parallel. By using this micro-lens array system, we fabricated 800 micro-springs and micro-cubic structuresby single laser scanning[5]. In this presentation, metalization of fabricated polymer structures will also be described. We coat metal on the surface of polymer by electroless metal plating, but not on the glass substrate [6]. Hydrophobic coating was pre-made on the glass substrates and polymer surface is modified with Sn2+-ions. With this method micro-coil array is metalized [7]. Micro-coil array exhibits negative refraction due to the excitation of magnetic field through coils. We would like to show our design of the structure [8]. In the end, we talk about our newly invented diffraction-free imaging with nano metal rod array [9].[1] S. Kawata, et. al, Nature 412 (2001) 697.[2] S. Maruo, et. al, Opt. Lett. 22 (1997) 132.[3] K. Kaneko, et. al, Appl. Phys. Lett. 83 (2003) 2091.[4] K. Takada, et al, Appl. Phys. Lett. (submitted).[5] J. Kato, et al, Appl. Phys. Lett. 86 (2005) 044102.[6] N. Takeyasu, et. al, Jpn. J. Appl. Phys. Part2, 44 (2005) L1134.[7] F. Florian, et. al, Appl. Phys. Lett. (submitted).[8] A. Ishikawa, et al, Phys. Rev. Lett. (accepted for publication).[9] A. Ono, et. al, Phys. Rev. Lett. (accepted for publication).
3:00 PM - T2.2
Titania-Polymer Hybrids for Two-Photon Microfabrication.
Wenting Dong 1 , Joseph Perry 1
1 School of chemistry and biochemistry, Georgia Institute of Technology, Atlanta, Georgia, United States
Show AbstractTwo-photon microfabricaton (TPM) is an efficient nonlinear optical lithographical technique for the fabrication of three dimensional micro- or nano-structures including photonic crystals, which have potential applications in opto-electronics and photonics. The development of new photopatternable materials, such as metal-oxide polymer hybrids, for TPM will expand the scope of this fabrication method and allow the creation of structures for a wider range of applications. Woodpile-type structures are well known photonic crystal structures and polymeric woodpiles have been made by TPM. However, most materials used in such fabrication have been epoxy or acrylate based polymers or silica-polymer hybrids and the refractive indices of these materials are not high enough to achieve 3D photonic band gaps. In this presentation, we will describe one prospective way to increase the refractive index of the material system by using photopatternable titania-polymer hybrid materials. Titania-polymer hybrid materials were chosen because titania can contribute a high index to the material as it has an index of 2.8 for anatase and 3.01 for the rutile phase. A titania-polymer precursor was prepared by forming a complex of a titanium tetra-alkoxide with an acrylate substituted acetoacetonate. Using photoexposure following a weak initial hydrolysis and condensation, we have demonstrated photopatterning of thin and thick films of this precursor to form a titania-polymer hybrid structures. Well-ordered 3D woodpile structures of titania-polymer hybrid were obtained by TPM after optimizing the composition and processing conditions. We will discuss the properties of the fabricated woodpile structures.
3:15 PM - T2.3
Wafer-Level Positioning of Nanoparticles using CMOS Technology and Wet Chemistry.
L.-C. Ma 1 , R. Subramanian 1 , H.-W. Huang 1 , V. Ray 1 , N. Basit 1 , C.-U. Kim 1 , S.J. Koh 1
1 , The University of Texas at Arlington, Arlington, Texas, United States
Show AbstractOne of the challenges toward the realization of nanoscale devices is to develop a technique which enables an accurate and reliable positioning of nanoscale objects (such as nanoparticles, carbon nanotubes, nanowires, and biological objects) onto the targeted locations. Furthermore, the positioning also needs to be carried out over the entire wafer in order to create millions of devices in parallel processes. Combining wet chemistry and CMOS fabrication technology, we have developed a method which enables the positioning of nanoparticles on lithographically defined locations over the entire wafer. Using selective formation of self-assembled monolayers (SAMs) of organic molecules, we have been able to form one-dimensional assemblies of gold nanoparticles on exact substrate locations defined on 300 mm silicon wafer. The degree of alignment of the 1-D nanoparticle assembly was near perfect and the standard deviation from the perfect line was measured 3.7 nm for 20 nm gold nanoparticle assembly. The length of the 1-D nanoparticle assembly can be made very long and reached more than tens of micrometers depending on the pattern. This technique also allows the exact positioning of gold nanoparticles (diameter of 20-100 nm) on the gap between two electrodes. This developed technique, the controlled positioning of nanoparticles between the electrodes, can be used for the fabrication of single electron devices as well as molecular electronic devices. It can also be applied for the positioning of other nanoscale objects in general. A new scheme for the fabrication of large-scale single electron devices will be presented, along with initial I-V measurements. *Supported by ONR (N00014-05-1-0030) and NSF CAREER (ECS-0449958).
3:30 PM - T2.4
Formation of Epitaxial Ge Nanorings on Si by Self-assembled SiO2 Particles and Touchdown of Ge Through a Thin Layer of SiO2
Qiming Li 1 , Sang Han 1
1 chemical and Nuclear Engineering, University of New Mexico, Albuquerque, New Mexico, United States
Show AbstractWe demonstrate that hexagonally packed single-crystalline Ge rings can be grown around the contact region between self-assembled SiO2 spheres and 1.2-nm-thick chemical SiO2 on Si. When the oxide-covered Si substrate is pulled from a colloidal suspension of SiO2 spheres, the SiO2 spheres self-assemble into a hexagonally packed monolayer on the substrate. These SiO2 spheres provide a surface diffusion path to guide the Ge adspecies to reach the substrate. We have previously determined that the Ge adspecies readily desorb from the bulk SiO2 surface with a desorption activation energy of 42±3 kJ/mol. This low desorption activation energy gives rise to a low surface diffusion barrier, which in turn leads to a high diffusion length on the order of several micrometers, exceeding the dimension of the SiO2 spheres. With a flux of Ge impinging at 45° from the surface normal, the Ge beam cannot directly impinge on the underlying substrate through the openings between SiO2 spheres. The Ge adspecies diffuse around the SiO2 spheres and "touchdown"[Li et al., APL, 85(11), 1928 (2004)] through the chemical SiO2, forming epitaxial ring structures. The touchdown process anchors nanoscale Ge seed pads to the underlying Si substrate. The ring formation uniquely takes advantage of the SiO2 sphere self-assembly; the weak interaction between Ge adspecies and SiO2; and the touchdown where Ge densely nucleate on Si surface through the 1.2-nm-thick chemical oxide.
3:45 PM - T2.5
Doping of Nanostrucures by Ion Implantation with Scanning Probe Alignment.
Thomas Schenkel 1
1 , LBNL, Berkeley, California, United States
Show AbstractWe have developed a scanning probe microscope that is integrated with ion beams [1]. Beams of dopant ions are collimated and transmitted through small holes in scanning probe cantilever tips. This allows non-invasive imaging of nanostructures and ion implantation into selected areas. We are currently adding a single ion detection capability which uses collection of secondary electrons or pick up of charge pulses inside a sample to register single ion impacts and thus allow placement of single dopants into selected device regions. We will discuss the potential of this technique with respect to throughput, aperture lifetime, imaging and ion placement resolution. [1] A. Persaud, et al., Nano Letters 5, 1087 (2005)
4:30 PM - **T2.6
Enabling Nanoscale Science and Engineering via Highly Flexible, Low-Cost, Maskless Lithography.
Henry Smith 1
1 EECS, MIT, Cambridge, Massachusetts, United States
Show AbstractThe role of lithography in the future development of nanoscale science and engineering is to put high-density spatial information into nanoscale assemblies. Because information content determines the functionality of such assemblies, lithography will almost certainly be a key enabler. Conventional lithographic techniques generally lack the flexibility, low cost and the resolution that research in nanoscale science and engineering requires. Although no single lithographic technique is likely to be a panacea, it is important to seek novel approaches that meet the needs of researchers and open a path to directly manipulating nanoparticles and macromolecules. We review the various forms of lithography and focus special attention on maskless zone-plate-array lithography, assessing its impact, advantages and extendibility to the limits of the lithographic process. Nanoscale assemblies will require control at the macromolecular level, and this has begun with research on templated self assembly. Going beyond that to the control and utilization of the information content of nanoparticles and molecules will require innovations whose origin is uncertain at this point.
5:00 PM - T2.7
Understanding and Control of Serial Shrinking Nanolithography
Zheng Li 1 , Arvind Mallikarjuna 1 , Li Tan 1
1 Engineering Mechanics and Center for Materials Research and Analysis, University of Nebraska-Lincoln, Lincoln, Nebraska, United States
Show AbstractMicrolithography has reached a level of maturity such that complex microstructures are produced with high throughput and good fidelity. However, further miniaturization of these structures to sub-100 nm scale presents great challenges, such as complication in tuning both feature size and density, lack of means for reducing line edge roughness, as well as a much concerned scalability for mass production. In this presentation, a novel approach in nanoscale manufacture, dubbed as Serial Shrinking Nanolithography (SSN), is introduced to fill these gaps; one that features high yield and high throughput, tunability of pattern dimension and density, nanometer level resolution, and at the same time is simple and inexpensive to operate.The dimension miniaturization and pattern formation in SSN can be realized through the repeated stretching and contraction of an elastomer substrate, where patterned features are formed first on a stretched substrate and subsequently miniaturized when the substrate relaxes. Repeating this process multiple times allows us to reach sub-100 nm scale, and functional nanostructures are then obtained by imprinting the sub-100 nm features onto desired surfaces.Since this nanomanufacture process involves a nonlinear and large-scale deformation in thin film structures, difficulties to seek an analytical guidance are encountered with conventional theoretical tools. To make this miniaturization process controllable with thorough understanding, modeling and simulation of SSN are provided through finite element analysis (FEA). Particularly, thin films are assumed to be the type of hyperelastic materials and the miniaturization process is evaluated by using Mooney-Rivlin theory with constitutive parameters derived from mechanical characterizations. Calculated numerical results revealed the appearance of pattern distortion and substrate fluctuation when the geometry of the pattern dimension and the mechanical loadings are not optimized. More interestingly, simulation-guided process is further integrated into SSN to fabricate ultrahigh density functional structures with resolution of sub-100 nm.We expect broad impacts of our nanomanufacturing approach that could lead to nanostructured devices and systems with enhanced efficiency and functionality, and possibly new opportunities for interfacing nanomanufacture with biology.
5:15 PM - T2.8
Nanopatterning of Si/SiGe Two-dimensional Hole Gases by PFOTS-aided AFM Lithography of Carrier Supply Layer.
Kun Yao 1 , James Sturm 1
1 Princeton Institute for the Science and Technology of Materials, Department of Electrical Engineering, Princeton University, Princeton, New Jersey, United States
Show AbstractFor Si-based quantum dots for single-electron devices, dots with zero surface states are desirable, since one surface state can greatly alter a single electron device. This is difficult to achieve with oxide passivation. We have previously shown the approach of defining SiGe quantum dots for holes by AFM lithography and wet etching (to avoid radiation damage defects from e-beam and RIE) and epitaxial regrowth of Si to passivate the SiGe dot surface with ideally zero interface states, resulting in vast improvement in Coulomb blockade single-hole FET’s [1]. This work was limited, however, by fact that (i) lithography and pattern transfer from AFM oxidation by wet etching were very non-reproducible, and (ii) the inevitability of interface contamination on the dot surface during regrowth, resulting in defect states. In this work, we report two significant advances to overcome these limitations: (i) the use of a self-assembled monolayer (PFOTS) [2] as an etch resist to improve the uniformity and repeatability of AFM lithography, and (ii) the patterning of the carrier supply layer of a 2-D hole gas by this method, rather than the SiGe conducting layer itself, so that a dot in the SiGe can be achieved without ever exposing its surface.By applying a negative bias to a scanning AFM tip on the sample, a 2nm Si cap on SiGe covered by PFOTS is oxidized. Linewidths well under 100 nm can be achieved. By a dilute HF dip to remove the SiO2 line and then a selective wet etching to remove the SiGe under the removed oxide, the pattern is transferred to the underlying SiGe layer. The previous process is limited by the thin Si cap which is not a good selective etch barrier -- with this additional PFOTS film as a resist, now the selective etch is not limited to short time, so thicker SiGe layers with lower Ge content can be patterned with far improved uniformity than without PFOTS. This process was applied to a 2-D hole gas with a 100Å B-doped Si0.88Ge0.12 layer as the carrier supply layer on a 80Å Si setback and a Si0.7Ge0.3 quantum well, with a measured hole density of 6×1011cm-2 in the well before patterning. To remove the supply layer by selective wet etch without the barrier layer, the supply layer was made of Si0.88Ge0.12 as opposed to the usual Si. This approach avoids the potential creation of defects on the surfaces of the resulting quantum dots, since throughout the whole process the Si0.7Ge0.3 in which the carriers reside is not exposed. This eliminates the requirement of subsequent epitaxial regrowth to passivate the dot surfaces. As a demonstration, we cut a line through the supply layer on a Hall bar mesa with the process. The two-terminal I-V curves with and without the cutting clearly show good quantum confinement.[1] X.-Z. Bo, L. P. Rokhinson, D. C. Tsui, and J. C. Sturm, Tech. Dig. Device Research Conference, pp.129-130 (2003).[2] K. Bierbaum, M. Grunze, A. A. Baski, L. F. Chi, W. Schrepp, and H. Fuchs, Langmuir 11, 2143 (1995).
5:30 PM - T2.9
Self-organized Patterns of Metallic and Semiconductor Nanoparticles Induced by Ion Sputtering and Ion-beam Assisted Deposition on Organic Thin Films.
Qiangmin Wei 1 , Sha Zhu 2 , Lumin Wang 1 2
1 Department of Materials Science and Engineering, University of Michigan, Ann Arbor, MI, Michigan, United States, 2 Nuclear Engineering & Radiological Sciences, University of Michigan, Ann Arbor, Michigan, United States
Show AbstractSel-organized nanopatterns of metallic and semiconducting nanoparticles (Cu, Si, etc.) on organic thin films are formed in an ion mill with 3-5 Kev Ar ion beam bombardment. These patterns were induced by ion beam assisted deposition of the sputtered atoms from the adjacent materials during the specimen rotation under the Ar ion beam at the glancing angle of incidence. Uniformly sized and shaped nanoparticles of 7 nm diameter with 2 nm separations and well ordered arrays of stripe-like organic-inorganic nanostructure with 7 nm wavelength were produced on the thin polymer film consisting of epoxy resins. The competition between kinetic roughening induced by ion sputtering and smoothing generated by surface viscous diffusion can contribute to this self-organized nanopattern formation. This approach illustrated a convenient route for fabricating nanometer scale surface patterns for metallic and semiconducting nanoparticles, which may have the potential for specific device applications.
5:45 PM - T2.10
Synthesis and Measurement of Magnetic Cobalt DNA-Templated Nanowire
Chia-Hsin Lin 1 , Hsin-Lung Chen 2 , Yi-Chun Liu 1 , Hsien-Kuang Lin 1 , Wen-Lian Liu 1 , Syh-Yuh Cheng 1 , Yachun Sun 1
1 Materials Research Laboratories, Industrial Technology Research Institute, Chutung, Hsinchu Taiwan, 2 Department of Chemical Engineering, National Tsing Hua University, Hsin-Chu Taiwan
Show AbstractBiomaterials such as DNA are currently being explored as potential application in nanotechnology. λ-DNA templates were immobilized on silanized SiO2 wafer by spin coating as a grid-like network. The DNA templates were then activated with PdCl2, followed by reduction with dimethylamine borane (DMAB) to form seeding nanoclusters on the DNA chain. Afterward the DNA chain with deposition of zero-valence Pd nanoclusters was grew in a Co electroless plating bath. SEM/EDS analysis revealed that Co nanoparticles could be assembled on the DNA template to form magnetic nanowires with a diameter of 50nm to 500nm by a conventional electroless plating. Vibrating Sample Magnetometer analysis indicated that Co-DNA nanowires deposited on SiO2 wafer showed a paramagnetic moment of around 10-3 emu in a magnetic field of 8000G, in contrast to the diamagnetic of bare SiO2 wafer, proving that the measured magnetism was indeed caused by Co-DNA-templated nanowire. Specific arrangement of bare DNA was effectively preserved after Co electroless plating. These characteristics indicated that DNA is an ideal template for the production of magnetic nanowires, which could be useful in the development of high-density memory storage or magnetic field sensors.
Symposium Organizers
Francesco Stellacci Massachusetts Institute of Technology
Joseph W. Perry Georgia Institute of Technology
Gregory S. Herman Hewlett-Packard Company
Rabindra Nath Das Endicott Interconnect Technologies
T3: Imprint and Particle Based Methods
Session Chairs
Chih-hung Chang
Francesco Stellacci
Wednesday AM, April 19, 2006
Room 2004 (Moscone West)
9:30 AM - **T3.1
Manufacturing at the Nanoscale.
Stan Williams 1
1 , Hewlett Packard Company, Palo Alto, California, United States
Show AbstractThere is currently a tremendous business incentive to invent new electronic devices and circuits that will have dimensions of the order of nanometers. In addition, new fabrication techniques will be required that can inexpensively produce and connect these devices in vast quantities. The challenges are equivalent to those faced by the inventors of both the transistor and the integrated circuit, who replaced the existing vacuum-tube and wiring technologies with solid-state switches and lithographic fabrication, respectively. In order to satisfy both requirements simultaneously, we have assembled a trans-disciplinary team of chemists, physicists, engineers, computer scientists and mathematicians at HP Labs. Two complementary research areas relevant to future nanocomputing systems are currently under investigation: (1) nano-scale switching devices and circuits for both electrons and photons, and (2) the development of new and inexpensive fabrication techniques. Our approach for the construction of electro-photonic circuits involves the explicit incorporation of defect tolerance, which is the capability to operate perfectly even in the presence of manufacturing mistakes in the circuit, into the design of the system. This prerequisite arises from the realization that it is prohibitively expensive to fabricate a perfect network of billions of nanoscale components. However, by introducing the appropriate amount of redundancy and utilizing concepts from coding theory, arbitrary complexity can be programmed into a highly regular structure and at the same time any defects can be avoided. Our research group has recently demonstrated the ability to fabricate electronic devices with sub-viral length scales (e.g. ~15 nm) and to build nanoscale devices with the capability to perform signal restoration and inversion (required for universal computing) without the need for transistors or any semiconductor at all. This has led us to discover an entirely new logic family based on the Boolean “Implication” operation that is specifically suited to the properties of nanoscale switches and crossbars. We have built and demonstrated memory and logic circuits based on these new ideas that exceed the density of today’s semiconductor circuits by one to two orders of magnitude. I will describe how fundamental research in a corporate research laboratory can be a strategic asset for the company, and how it is possible to mix curiosity-driven discovery with invention by the proper choice of research area.
10:00 AM - T3.2
Roll To Roll Nanopatterning Of Polymers Using A Novel Imprinting Device.
Tapio Makela 1 , Tomi Haatainen 1 , Paivi Majander 1 , Henrik Sandberg 1 , Jouni Ahopelto 1
1 , VTT Information Technology, Espoo Finland
Show AbstractHigh speed printing tools with submicron resolution have been already presented and used commercially in manufacturing of e.g. optical elements. [1] The resolution is normally limited to the few hundreds of nanometers. Nanoimprinting techniques can be used in a roll to roll process when the speed, temperature and pressure are precisely controlled. However, one limiting factor is how to achieve the submicron resolution in the roll stamp.In this work we have investigated roll to roll manufacturing of submicron structures using a custom built laboratory scale imprinting tool. [2] Results for imprinting on 95 µm cellulose acetate film using different speeds, while pressure and temperature are kept constant, are presented in the table.When regular thermoplastic polymers are used the imprint times reported usually exceeds tens of seconds. We have demonstrated earlier that the imprinting time can be reduced to a few seconds when the step & stamp imprint method is used.[2] Using the lowest speed in the machine the estimated imprinting time was 3 second. Nickel stamps [3] were used as imprinting stamp attached to a printing cylinder by using two-sided adhesive tape or sheets. Stamps were heated by using electrical heaters installed inside the printing cylinder.In this device a flexographic printing unit (FLEXO) and the imprinting unit can be used at the same time inline. First FLEXO can be used for printing a polymer layer on the substrate and right after that the imprinting unit is used to pattern the polymer. We have demonstrated this option by using inherently conductive Polyaniline-dodecylbenzenesulfonic acid (PANI-DBSA) in toluene as a printing ink. [4] Patterned conductive structures down to 200 nm on polypropylene are achieved when a speed of 0.5 m/minute and a pressure of 8.3 MPa are used. The layer’s conductivity of 27 S/cm does not change in the imprinting process. The temperature was varied from 25 C up to 100 C in the PANI-DBSA imprinting process. Roll to roll imprinted structures were analyzed using optical microscopy, AFM characterization and conductivity measurements.References:[1] M.T. Gale & Al., Optics and Lasers in Engineering 43 (2005) 373 -386[2] T. Mäkelä & Al. Trends in Nanotechnology (TNT2005). Oviedo, ES, 29 Aug. - 2 Sept. 2005. CD-ROM. PHANTOMS Foundation (2005) and 3rd international Conference on Nanoimprint and Nanoprint Technology, NNT2004. Wien, 1 - 3 Dec. 2004. Poster. AMO GmbH (Gesellschaft für angewandte Mikro- und Optoelektronik) (2004) [3] P. Majander & Al., 4th International Conference on Nanoimprint and Nanoprint Technology, NNT2005, Nara, 19-21 Oct. 2005. Poster[4] T. Mäkelä & Al., to be published
10:15 AM - T3.3
Nano-Imprint Transfer of Gold Nano-Wires.
Chih-Chieh Shu 1 , Jie-Ting Wu 1 , Chih-Chiang Chao 2 , Fon-Shan Huang 1
1 Institute of Electronics Engineering, National Tsing Hua University, Hsinchu Taiwan, 2 Union Chemical Laboratories, Industrial Technology Research Institute, Hsinchu Taiwan
Show Abstract The study of gold nano-wires transferred on hydrogen silsesquioxane (HSQ) by hot-embossing was investigated. The photoresist (DSE1010) with the thickness 350nm was spin-on coated on Si (100) wafer. The gold nano-wires were deposited by immersing the nano-trench lines with width 150~200nm fabricated by E-beam lithography into plating solution. The plating solution was obtained by adding 0.1~1 (ml) HF solution and 0.3~5 (ml) HAuCl4 solution into 10ml DI water and stirring at room temperature for 3~5 minutes. The HSQ (FOX-15, Dow Corning) diluted in MIBK (1:0~4:5) was spin-on coated on Si (100) wafer with thickness around 250~600nm. The HSQ was then prebaked at 50~150°C for 3 minutes in order to adjust its viscosity and hardness. The gold nano-wires were transferred from the Si mold onto the HSQ by nano imprint at temperature 25~180°C with pressure 2.5~6Mpa. The imprinting system used in this experiment is EVG 520HE. After immersing in plating solution, the Si trench lines are converted into Au nano-wires. The width of Au nano-wire is a little larger than the width of trench. It might be due to DSE1010 etched by plating solution. From top view and cross-section of SEM pictures, we observe that the grain growth of gold nano-wires will vary with the nano-trench width. After imprinting, Au nano-wires with 234 nm in width have fidelity transfer. But the probability of the small cluster growth in narrow line is larger than that in wide line; the parts of these small grains with the less rough surface in narrow line can’t be embedded into HSQ during imprinting. The result transfer yield falls off with the line width decreases. SEM shows that the wider gold wires have better transferring result than narrower gold wires. Most of transferred Au nano-wires fail for 3M scotch tape test. In the future, adhesion improvement is a main task for our study.
10:30 AM - T3.4
Fabrication of Metal Nanowires at 17nm Half-pitch by Nanoimprint Lithography.
Gun Young Jung 1 , Wei Wu 1 , Zhaoning Yu 1 , Zhiyong Li 1 , Shih-Yuan Wang 1 , William Tong 1 , Richard Williams 1 , Ezekiel Johnston-Halperin 2 , James Heath 2
1 Quantum Science Research group, Hewlett Packard Labs, Palo Alto, California, United States, 2 Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California, United States
Show AbstractNanoimprinting lithography was initiated as an alternative way to achieve nanoscale structures with high throughput and low cost. The nanoscale structures are transferred from a mold to thermoplastic or UV-curable monomer film during the imprinting process. To transfer patterns on this film, the film was treated with either temperature or UV shining while the hydraulic pressure was applied, resulting in a replica of the mold on the polymer layer. Final metal or semiconductor patterns were accomplished by evaporating metals and lifting off the polymers. We have produced a rewritable, nonvolatile, molecular memory device based on an 8×8 cross bar structure with a density of 6.4 Gbit/cm2 by thermal imprint lithography. The linewidth of nanowire was 40 nm with 65 nm half-pitch (hp) size.1 34×34 nanowires crossbar structure was also fabricated by UV-based nanoimprint lithography with linewidth of 35 nm at 50 nm hp.2 Furthermore, we demonstrated the 66×66 nanowires crossbar at 30 nm hp3 incorporated with demultiplexer to select one of the 66 nanowires. We also fabricated high density metal cross-bars at 17 nm half-pitch using the superlattice nanowire pattern transfer technique. A 300 layer GaAs/AlGaAs superlattice was employed to produce an array of 150 Si nanowires (15 nm wide at 34 nm pitch) as an imprinting mold. A cross-bar platinum nanowire array with a cell density of approximately 100 Gbit/cm2 was fabricated by two consecutive imprinting processes. 1.Y. Chen, G.Y. Jung, D.A.A. Ohlberg, X. Li, D.R. Stewart, J.O. Jeppesen, K.A. Nielsen, J.F. Stoddart, and R.S. Williams, J. Nanotechnology, 14, 462 (2003)2.G.Y. Jung, S. Ganapathiappan, D.A.A. Ohlberg, D.L. Olynick, Y. Chen, W.M. Tong and R.S. Williams, Nano letters, 4, 1225 (2004)3.G.Y. Jung, W. Wu, S.Y. Wang, William M. Tong and R. Stanley Williams, J. Photopolymer science and technology, 18, 565 (2005)
10:45 AM - T3.5
Dip-pen Nanolithography Patterned Bismuth Nanowires for Thermoelectric Application.
P.G. Ganesan 1 , Omkaram Nalamasu 1
1 Center for Integrated Electronics, Rensselaer Polytechnic Institute, Troy, New York, United States
Show AbstractNanomaterials have a relevant importance for industrial applications since they have unique mechanical, optical and electrical properties. It is well known that certain physical and electrical properties of materials considerably change as one of their dimensions is reduced to nanoscale. Such nanostructured materials could acquire better thermoelectric properties than their bulk counterparts and could attain the kind of performance need for widespread application of thermoelectric technology in power generations and refrigeration.In thermoelectric materials, a temperature gradient creates motion of charged particles that produces a voltage, leading to the flow of current when the material is connected in a circuit. This effect could be used to extract power from small temperature gradients, such as those produced by some geothermal processes, which are currently too ‘dim’ to allow for economical energy generation. A good thermoelectric material should have high electrical conductivity like a crystalline materials and a low thermal conductivity like a glass, as the suggested concept of “phonon-glass/electron-crystal” (PGEC) model. The nanostructured materials are also PGEC materials due to the reduction of thermal conductivity by the phonon blocking effect of nanostructures. Bismuth telluride and its alloys are most important thermoelectric materials used in state-of-the-art device for the 200-400 K temperature range. There is a few work has been done on synthesis of nanostructured thermoelectric materials such as nanowires arrays and quantum dot supperlattice thin films. We use entirely new approach to fabricate of nanostructured thermoelectric materials. Bismuth nanowires were formed on chemically cleaned silicon substrate by electrochemical dip-pen nanolithography technique. This technique allows us to generate complex patterning of materials. We used negative bias to scanning probe microscope tip to electrochemically decompose bismuth acetate precursor. We optimized patterning condition such as humidity and temperature in order to obtain best writing. Lateral force micrograph of the bismuth patterns indicates the possibility of silicon oxide formation underneath of bismuth nanopatterns. Based upon our results, we will present a phenomenological model of thermoelectric nanowires formation using dip-pen nanolithography technique. Such approaches of building nano-structures could open up new flexible assembly strategies to create architectures for thermoelectric applications such as power generation, sensing, and refrigeration.
11:30 AM - **T3.6
Nanofabrication for Multipurpose Applications: From Nanoptics to Biomedicine.
Enzo di Fabrizio 1 2
1 , INFM - TASC, Trieste Italy, 2 , University of Magna Graecia at Catanzaro, Catanzaro Italy
Show AbstractThe importance of nanotechnology on several research fields, is becoming well known in a wider research community. Nanolithographic techniques, combined with other fabrication processes are becoming popular in new fields such as nanophotonics, soft matter, biology, medicine etc.Nanofabrication, nowadays, is widely employed for producing devices with new functions and possibly, with multi-functional operations. A modern scientist will be asked to be able to design, fabricate and characterize devices for particular or multi-purpose applications. The lecture will show the most recent results, obtained by our group, ranging from nanooptics to applications of nanoporous silicon for biomedical research. Details on nanofabrication and characterization will be given for each device and future applications, in different areas, will be illustrated.
12:00 PM - T3.7
Surface Plasmon Interference Nanolithography
Zhaowei Liu 1 2 , Jie Yao 1 , Werayut Srituravanich 1 2 , Xiang Zhang 1 , Qihuo Wei 3
1 , University of California, Berkeley, Berkeley, California, United States, 2 , University of California, Los Angeles, Los Angeles, California, United States, 3 Applied NanoBioscience Center, Arizona State University, Tempe, Arizona, United States
Show AbstractAs the most widely used form of lithography method for almost all micromanufacturing purposes, photolithography was limited by the physics of diffraction. In order to achieve nanometer feature sizes, either the working wavelength has to be reduced, or alternative techniques of pattern transfer such as nanoimprinting lithography (NIL) have to be adopted. The main approach to reducing the working wavelength is to directly use light sources of higher photon energy such as extreme ultraviolet light (EUV) or soft x-rays. However, accompanying with this reduction of the exposing wavelengths is the drastic increase of complexity and cost for instrumentation and processing. We propose a new nano-photolithography technique based on the interference of surface plasmon waves. The wavelengths of the surface plasmon waves at metal and dielectric interfaces can reach the nanometer scale while their frequencies remain in the optical range. As a result, the resolution of this surface plasmon interference nanolithography (SPIN) can go far beyond the free-space diffraction limit of the light. Both simulation and experimental results show that the 1D pattern feature size of SPIN can go down to ~50nm using i-line (365nm) exposure light. Two dimensional periodical or quasi-periodical structures can also be patterned using SPIN. Detailed characteristics of SPIN such as field distribution and contrast are also investigated. This technique provides a new alternative fabrication method for nanodevices.
12:15 PM - T3.8
Proton Beam Writing: High Aspect Ratio 3D Nano Patterning of HSQ Resist.
Jeroen van Kan 1 , Andrew Bettiol 1 , Frank Watt 1
1 physics, CIBA, Singapore Singapore
Show AbstractWednesday, April 19Presentation Time and Paper Number change11:15 AM T3.8Proton Beam Writing: High Aspect Ratio 3D Nano Patterning of HSQ Resist. Jeroen A. van Kan
12:30 PM - T3.9
Patterning of Ge Nanoparticles by Focused Electron Beam.
Nan Jiang 1
1 Physics, Arizona State University, Tempe, Arizona, United States
Show AbstractWednesday, April 19Presentation Time and Paper Number change11:30 AM T3.9Patterning of Ge Nanoparticles by Focused Electron Beam. Nan Jiang
T4: Biological and Scanning Probe Techniques
Session Chairs
Rabindra Das
Francesco Stellacci
Wednesday PM, April 19, 2006
Room 2004 (Moscone West)
2:30 PM - T4.1
Arrays of (CdSe)ZnS Quantum Dots Assembled on Cellulose Template via Engineered Protein and Their Photophysics Study
Xin Ai 1 , Qi Xu 1 , Marcus Jones 1 , Shi-you Ding 1 , Mike Himmel 1 , Garry Rumbles 1
1 , National Renewable Energy Laboratory, Golden, Colorado, United States
Show AbstractColloidal quantum dots (QDs) have attracted extensive attention due to their size-dependent optical and electronic properties. Although the properties of these nanoparticles in isolation render them huge potential application in bio-labeling and bio-imaging, other rapid developed appliances such as electronic and photovoltaic devices always require large scale patterning. Particularly an efficient, straightforward, low-cost and nontoxic method is preferred. We have successfully utilized nature template, cellulose combined with engineered proteins, carbohydrate-binding modules (CBMs), to obtain controlled arrays of ZnS capped CdSe quantum dots. The photophysical properties of the aligned (CdSe)ZnS QDs with different size have been characterized by steady state and time-resolved photoluminescence spectroscopy. This study provides a novel possible solution to bottom-up device fabrication.
2:45 PM - T4.2
Cell Manipulation and Tissue Engineering at the Nanoscale.
Michael Giersig 1
1 Nanoparticle Technology, caesar, Bonn Germany
Show Abstract3:00 PM - T4.3
Biomolecular Recognition of Crystal Defects.
Asher Sinensky 1 , Angela Belcher 1
1 Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts, United States
Show Abstract3:15 PM - T4.4
Assembly of 1-D Viral Particles at Chemical Templates.
Yu Huang 1 2 , Chin Li Cheung 1 , Chung-Yi Chiang 3 , Angela Belcher 3 , James De Yoreo 1
1 Chemistry and Materials Directorate, Lawrence Livermore National Labs, Livermore, California, United States, 2 , University of California, Los Angeles, California, United States, 3 , Massachusetts Institute of Technology, Cambridge, Massachusetts, United States
Show AbstractM13 bacteriophage is a type of 1D virus composed of different protein subunits. The functionality of these subunit proteins can be modified specifically through genetic engineering. Modification of the major coat protein as well as minor coat proteins at the virus ends has been successfully demonstrated to form functional heterostructured templates for precisely-positioned nanomaterials. Moreover, the intrinsic anisotropic virus structure is well-suited for the growth of monodisperse, highly crystalline nanowires and promising as an element of well ordered nanostructures. Because the individual sites on viruses can be engineered to present catalytic, electronic, or optically active properties, control over virus organization defines a route to nanoscale device fabrication. Assembly of 1D viral particles into 3D liquid crystal form has long been a subject of study, while little research has been done to understand the physics of organization of these viruses into 1D or 2D structures. Here we report results using scanned probe nanolithography (SPN) to direct organization of M13 bacteriophage into 1D and 2D patterns and in situ AFM imaging to investigate the physics of organization as pattern geometry, virus flux, and virus-pattern surface interaction are varied.As a model system, we chose M13 virus genetically engineered to present anti-streptavidin binding on one end of the virus. Atomically-flat gold substrates coated with SAMs of polyethylene glycol (PEG) terminated alkyl thiols were patterned with biotin-terminated alkyl thiols using SPN. The pattern was later reacted with streptavidin to form a streptavdin patterned surface through the interaction between biotin and streptavidin. Template features had sizes ranging from 10-100nm that were separated by 1000 to 2000nm. AFM was then used to investigate the degree of ordering and assembly kinetics. Furthermore, since M13 virus has a wire-like structure with an aspect ratio of ~100 (diameter ~8nm, length ~800nm), they exhibited specific ordering behavior under the influence of laminar flow. Studies were also carried out to investigate the effects of flow on virus ordering using a mcirofluidic channel to flow viruses over the pattern. This work was performed under the auspices of the U. S. Department of Energy by the University of California, Lawrence Livermore National Laboratory under Contract No. W-7405-Eng-48.
3:30 PM - **T4.5
Synthetically Programmable Materials and Devices Bonded Upon DNA.
Chad Mirkin 1
1 Chemistry, Northwestern University, Evanston, Illinois, United States
Show AbstractThis presentation will describe methods or synthesizing oligonucleotide modified nanoparticles and their use in construction of functional materials and devices. Specific emphasis will be on highly miniaturized nucleic acid diagnostic systems and high thoroughput methods for screening the interactions between small molecules and DNA.
4:30 PM - **T4.6
Synthesis of Nanostructures using Scanning Probes and Non-Covalent Binding
Christopher Gorman 1
1 Department of Chemistry, North Carolina State University, Raleigh, North Carolina, United States
Show AbstractThis talk will illustrate several methodologies developed in our group for the synthesis of surface-bound nanostructures. Our goal is to create a system in which the electronic properties of these nanostructures can be systematically controlled. Features that are of interest to control include domain size, packing density, and the ability to insert and remove both 'conducting' and 'insulating' moieties to/from the nanostructure using noncovalent interactions. Correlation between the type of assembly and its electronic properties will be illustrated.
5:00 PM - T4.7
Growth of Metal and Semiconductor Nanostructures on Templates of RNA-aptamer Catalysts Formed by Scanned Probe Nanolithography.
Sungwook Chung 1 , John LaTour 1 , Theodore Tarasow 1 , James De Yoreo 1 , Bruce Eaton 2 , Daniel Feldheim 3
1 Chemistry and Materials Science Directorate, Lawrence Livermore National Laboratory, Livermore, California, United States, 2 Chemistry and Biochemistry, University of Colorado at Boulder, Boulder, Colorado, United States, 3 Chemistry, North Carolina State University, Raleigh, North Carolina, United States
Show AbstractOrganizing nanostructures into deterministic patterns at surfaces is a fundamental challenge of nanoscience. Combining self-assembly with nanolithography in which chemical patterns serve as templates to define the locations of nanoparticle attachment has been investigated as one potential solution. But to be generally applicable to multi-component systems, this approach requires a variety of linker molecules that can be used to selectively template a wide range of materials. Moreover, these compounds must be amenable to nanoscale patterning on surfaces in a functional state. Recently, RNA-aptamers were demonstrated as catalysts for synthesis of metal and semiconductor nanoparticles. Here we report results using scanned probe nanolithography to create patterns of RNA-aptamers that serve as catalytic templates for the growth of metal and semiconductor nanoparticles. We also present results from atomic force microscopy studies on nucleation and growth of nanoparticles at these templates and electron microscopy investigations of the resulting morphologies and structures.This work was performed under the auspices of the U. S. Department of Energy by the University of California, Lawrence Livermore National Laboratory under Contract No. W-7405-Eng-48.
5:15 PM - T4.8
Electron-beam Directed Layer-by-Layer Assembly of Dendrimer Scaffold for Biomolecule Patterning.
Parijat Bhatnagar 1 , Sonny Mark 2 , Il Kim 3 , Hongyu Chen 3 , Brad Schmidt 4 , Michal Lipson 4 , Carl Batt 3 1 2
1 Department of Biomedical Engineering, Cornell University, Ithaca, New York, United States, 2 Department of Microbiology, Cornell University, Ithaca, New York, United States, 3 Department of Food Science, Cornell University, Ithaca, New York, United States, 4 Department of Electrical and Computer Engineering, Cornell University, Ithaca, New York, United States
Show AbstractA method for patterning biomolecules using electron beam (e-beam) lithography has been developed(1). First, a non-biofouling poly (ethylene glycol) terminated self-assembled monolayer (SAM) was deposited on a silicon oxide substrate. This SAM was then ablated by e-beam to create patterns aligned with the pre-existing features on the wafer. Aldehyde-terminated polyamidoamine (PAMAM) dendrimers were assembled in a layer-by-layer fashion in the ablated patterns to allow the covalent immobilization of oligonucleotide probes. The aminated oligonucleotides were attached using Schiff base chemistry followed by reductive amination. The functionality of the attached oligonucleotides was demonstrated by the hybridization of fluorescently labeled complementary target oligonucleotides. The hybridized target oligonucleotides could be stripped and the regenerated surface bound probe oligonucleotides could be rehybridized with complementary target oligonucleotide.1. Parijat Bhatnagar, Sonny S. Mark, Il Kim, Hong Yu Chen, Brad Schmidt, Michal Lipson, Carl Batt. Dendrimer Scaffold based Electron Beam Patterning of Biomolecules. Advanced Materials, Manuscript number: adma.200501170, in press.
5:30 PM - T4.9
Fabrication of Luminescent Materials using Biogenic Nanostructured Oxides from Marine Diatoms.
DooHyoung Lee 1 , Clayton Jeffryes 1 , Tian Qin 1 , Gregory Rorrer 1 , Chih-hung Chang 1 , Timothy Gutu 2 , Jun Jiao 2
1 Chemical Engineering, Oregon State Univ., Corvallis, Oregon, United States, 2 Department of Physics, Portland State University, Portland, Oregon, United States
Show AbstractMarine diatoms are single celled microalgae that possess cell walls composed of amorphous silica nanoparticles. These organisms actively assimilate silicic acid Si(OH)4 from seawater, polymerize silicic acid to silica nanoparticles by a protein-mediated precipitation process, and then assemble the silica nanoparticles into intricate patterns that constitute the cell wall microarchitecture (consists of around 30nm of SiO2 nanoparticles) of the diatom frustule. Their exponential growth in cell cultures offer a mass production route to manufacture 3D nanostructured oxides. The diatoms can be viewed as microscale chemical reactors that are ideal for self replicating nanomanufactruing. We have harnessed the biomineralization capacity of marine diatoms to biologically manufacture nanostructured oxides (e.g. Silicon, Germanium oxides). Strong blue photoluminescence was observed from these biogenic nanostructured oxides [1]. To further extend the range of luminescent spectra, we are developing processes to fabricate nanostructured phosphors through a combination of biogenic nanostructured oxides with low temperature soft solution deposition techniques like chemical bath deposition (CBD) and successive ionic layer adsorption and reaction (SILAR). CBD is an aqueous analogue of chemical vapor deposition. The constituent ions are dissolved in a solvent, and the thin films are produced through a heterogeneous surface reaction. SILAR process proceeds via a layer-by-layer growth mechanism that is similar to atomic layer deposition. A variety of nanostructured phosphors with tunable luminescent properties were successfully obtained from this approach. [1] S.-H. Liu, C. Jeffryes, G. L. Rorrer, C.-H. Chang, J. Jiao, T. Gutu: Blue Luminescent Biogenic Silicon-Germanium Oxide Nanocomposite, in Biological and Bio-Inspired Materials and Devices, edited by K.H. Sandhage, S. Yang, T. Douglas, A.R. Parker, and E. DiMasi (Mater. Res. Soc. Symp. Proc. 873E, Warrendale, PA , 2005), K.1.4.1 - K1..4.6This research is supported by National Science Foundations’ Nanoscale Interdisplinary Research Team grant number BES-0400648.
5:45 PM - T4.10
Template Routes to Non-Oxide Ceramic Nano- and Micro-Structures.
Upal Kusari 1 , Zhihao Bao 2 , Y. Cai 2 , Gul Ahmad 2 , Kenneth Sandhage 2 , Larry Sneddon 1
1 Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania, United States, 2 School of Materials Science and Engineering, Georgia Institute of Technology, Atlanta, Georgia, United States
Show AbstractT5: Poster Session: Manufacturing, Materials, and Methods
Session Chairs
Thursday AM, April 20, 2006
Salons 8-15 (Marriott)
9:00 PM - T5.1
Thermoplastic Acrylic Lacquer as a Base for Hot Embossing.
P. Leech 1 , Robert Lee 1
1 , CSIRO CMIT, Clayton, Victoria, Australia
Show AbstractHot embossing has become a key technique in the replication of nano- and microstructures. The hot embossing process has typically used a film of thermoplastic polymer as the workpiece. In this paper, we report on the novel replication of grating arrays in thermoplastic acrylic lacquer. The master images for the process were fabricated by electron beam lithography as grating arrays with groove widths in the range 0.1-0.65 µm. The finer gratings (0.1-0.3 µm) consisted of test structures of varying spacing and linewidth. The arrays of coarser gratings (0.35-0.65 µm groove width) were arranged over an area of ~2 cm square in order to produce a diffractive portrait or geometric images [1]. The relief structure was transferred from the ZEP7000 resist to a nickel mold by electroplating. The structures were then embossed into a layer of cured acrylic lacquer at temperatures of 120-140 °C using a force of 80-120 kN. A temperature above the glass transition temperature for the lacquer, Tg = 120 °C was required in order to achieve a uniform impression across the embossed area of 8 x 8 cm. An analysis of the embossed structures by scanning probe microscope has shown a high quality of replication of the grating arrays in the lacquer for both the fine and coarser gratings. In the diffractive images (0.35-0.65 µm groove width), a series of optically variable effects have been demonstrated which were similar to holograms in conventional metallised foil. This paper reports for the first time on the use of acrylic lacquer (or automotive paint) in the hot embossing of nanoscale structures. The advantages of this workpiece are the low cost, ease of application and an enhanced ability to integrate the embossed structure with the surrounding coating. [1]. R.A. Lee, Microelectronic Engineering, 53 (2000) 513.
9:00 PM - T5.10
Nanotextured Self-Rolled Polymer Micro-Tubes.
Yen Peng Kong 1 , Albert Yee 1
1 Chemical Engineering and Materials Science, University of California, Irvine, Irvine, California, United States
Show AbstractWe report on a technique for fabricating nanotextures on curved, tubular polymer surfaces. Biological cell behavior and locomotion in a two dimensional (2-D) in-vitro environment have been extensively studied. However, in reality, cells interact in-vivo with micrometer and nanometer features and structures in a three dimensional (3-D) extracellular matrix. Therefore researchers have been using collagen scaffolds, hydrogels, electrospun scaffolds and other 3-D extracellular matrix for mimicking materials for cell studies. Cells cultured in artificial 3-D extracellular matrices have exhibited cell behavior and interaction that is different from 2-D cell behavior but it is difficult to attribute such differences to specific dimensional scales, local compliance or chemical cues. This difficulty is in part due to the difficulty of characterizing these artificial matrices in the nanometer scale and also in part due to the difficulty of reproducing the position of specific cues in 3-D from sample to sample. To overcome these difficulties, one must be able to engineer a 3-D cell matrix to have specific local physical and chemical cues in a reproducible way.We have fabricated self-rolled polymer microtubes having nanotextures on both inner and outer surfaces. These tubes can have diameters of roughly the size of a single cell or a cluster of cells and the inner and outer surfaces of the tubes can have various nanotextures. The length of these tubes can range from several mm to several cm. In this way, the behavior of a single cell to a cluster of cells can be examined. We use a variation of nanoimprinting known as reversal imprinting to reproducibly form the nanotexture. A sacrificial polymer layer that also functions as a mold is first reversal imprinted onto a silicon wafer. Onto this sacrificial polymer mold, a poly(dimethyl siloxane) (PDMS) layer is spin coated and cured. The surface of this PDMS coating is then O2 plasma treated and a third layer of crosslinkable poly(vinyl alcohol) (PVA) is then reversal imprinted onto the PDMS layer. To form a tube, the sacrificial polymer mold is removed with a solvent and this solvent also swells the PDMS layer. The swelling induces a strain in the PDMS-PVA bilayer and this strain gives rise to a bending moment that rolls the PDMS-PVA bilayer into a tube. The strain arising from crosslinking PVA on PDMS also contributes to the bending moment.We will present data showing the diameter scalability of the tubes and compliance measurements of tubes formed over trenches using an atomic force microscope. We will also present some preliminary observations of cell interaction with the nanotextured tubes.
9:00 PM - T5.11
Transport Properties of the Nanoporous Hydrogels Synthesized using PCL-PEO-PCL Block Copolymers.
Jungmee Kang 1 , Kenneth Beers 1
1 Chemical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts, United States
Show AbstractNanoporous hydrogels were synthesized using aqueous solutions of poly(epsilon-caprolactone)-poly(ethylene oxide)-poly(epsilon-caprolactone) (PCL-PEO-PCL) triblock copolymers. Aqueous solutions of the triblock copolymers underwent crosslinking processes in an electron beam to achieve chemical crosslinks in the PEO block, followed by degradation of PCL by hydrolysis to produce nanoporous hydrogels. Small Angle X-ray Scattering (SAXS) studies show microstructures of 30~50nm in the triblock copolymers at various polymer concentrations, and lamellar or cylindrical microstructures at high polymer concentrations. The crosslinked triblock copolymers at 80% were investigated with Atomic Force Microscopy (AFM) in a dried state, and a lamellar structure was observed with a length scale of 20~30nm. The transport properties of the resulting nanoporous hydrogels were investigated by Fluorescence Recovery After Photobleaching (FRAP) diffusion experiments and compared to hydrogels produced by the crosslinking of PEO homopolymer.
9:00 PM - T5.12
Fabrication of Polymeric Composite Nanostructures Containing Ferritin Nanoparticles and Carbon Nanotubes.
M. K. Shin 1 , S. J. Park 1 , S. G. Yoon 1 , C. K. Lee 1 , S. R. Shin 1 , K. M. Shin 1 , M. S. Kim 1 , B. K. Gu 1 , Y. J. Kim 1 , S. J. Kim 1
1 Dept. of Biomedical Engineering, Hanyang University, Seoul Korea (the Republic of)
Show Abstract Recently, composite nanostructures containing nanoparticles or carbon nanotubes (CNTs) have attracted much attention due to the possibilities of their enhanced mechanical, electrical, and magnetic properties [1-4]. In particular, it is very useful to embed nanoparticles or CNTs with good electrical properties in a nonconducting polymeric nanostructure because of a potential application for nanowires covered with an insulating shell. Even though there are many methods for fabricating composite nanostructures, electrospinning has been a useful technique for producing polymeric composite nanostructures due to the convenient conversion of polymer blend solutions into composite nanostructures at room temperature [5]. On the other hand, ferritin nanoparticles and CNTs have been a good candidate as a material with electrical properties. Because the nanoscale biomolecule ferritin, an iron storage protein, has electrochemical and electrical properties [6-8], it has been used for potential application as a nano-bio battery and a bio-fuel cell. The CNTs has intrinsic properties such as high electrical conductivity and protein-affinity [9,10]. Therefore, when the ferritin or the ferritin-CNT conjugates were incorporated in polymeric nanofibers, biocompatible composite nanofibers with electrical properties can be fabricated. In this work, PVA/ferritin nanofibers and PVA/CNT/ferritin nanofibers were fabricated for one-dimensional nanofibers with the electrical properties by using an electrospinning process. These nanostructures are applicable to biocompatible nanostructures requiring electrical properties.References1. 1. K. Mallick, M. J. Witcomb, A. Dinsmore, and M. S. Scurrell, Langmuir 21, 7964 (2005).2. M. Wang, H. Singh, T. A. Hatton, G. C. Rutledge, Polymer 45, 5505 (2004).3. R. J. Tseng, J. Huang, J. Ouyang, R. B. Kaner, and Y. Yang, Nano Lett. 5, 1077 (2005).4. T. Song, Y. Zhang, T. Zhou, C. T. Lim, S. Ramakrishna, and B. Liu, Chem. Phys. Lett. 415, 317 (2005).5. Z. M. Huang, Y. Z. Zhang, M. Kotaki, and S. Ramakrishna, Comp. Sci. & Tech. 63, 2223 (2003).6. C. E. Theil, Annu. Rev. Biochem. 56, 289 (1987).7. T. D. Martin, S. A. Monheit, R. J. Niichel, S. C. Peterson, C. H. Campbell, and D. C. Zapien, J. Electroanal. Chem. 420, 279 (1997).8. D. Xu, G. D. Watt, J. N. Harb, and R. C. Davis, Nano Lett. 5, 571 (2005).9. S. Iijima, Nature (London) 354, 56 (1991).10. Y. Lin, L. F. Allard, and Y. P. Sun, J. Phys. Chem. B 108, 3760 (2004).
9:00 PM - T5.13
Inkjet Printing of Functional Micro- and Nanostructured Materials.
Chih-Hung Chang 1 , DooHyoung Lee 1 , Yu-Jen Chang 1 , Gregory Herman 2
1 Chemical Engineering, Oregon State Univ., Corvallis, Oregon, United States, 2 , Hewlett-Packard Company , Corvallis, Oregon, United States
Show AbstractCrystals are organized matter that is ubiquitous in our daily life ranging from common table salt and sugar to more alluring gemstones like diamond. Crystals with specific patterns and shapes at the micro scale are often created for the microelectronics and microelectromechanics through capital and energy intensive facilities and processing conditions. In the past few years there are growing interests and efforts towards fabricating functional materials and devices via inkjet printing which offers a low-cost materials-efficient process in atmospheric environment. Here we report the formation of self-organized micro- and nanostructured functional inorganic materials through solution crystallization from inkjet printed micro-droplets. We were able to form several unique non-equilibrium micro- and nanostructures (snowflakes, dendrites, needles, dense branches, and nanopores .. etc.). Furthermore, functional thin film electronics were fabricated using these inkjet printed nanostructured films. This technique allows precise control of droplet location, concentration, and film thickness and would be a viable method for low-cost manufacturing of micro- and nanostructured materials. This research is supported by Hewlett Packard Co. Corvallis and National Science Foundation’s Process and Reaction Engineering Program under under a CAREER grant # CTS-0348723.
9:00 PM - T5.14
Reflectins: Characterization of Nature's Optical Material.
Ryan Kramer 1 , Wendy Crookes-Goodson 1 , Rajesh Naik 1
1 Materials and Manufacturing Directorate, Air Force Research Laboratory, Wright-Patterson AFB, Ohio, United States
Show AbstractSeveral evolutionary adaptations in biology that manipulate and interact with light have been demonstrated in a number of different terrestrial and aquatic organisms. The apex of this dynamic light interplay has been reached in cephalopods to include squid, octopi, and cuttlefish, which use a host of physiological adaptations in concert to dynamically alter light. One such adaptation, which can be found throughout this family, is the presence of reflective elements that results from a cumulative Bragg reflection of multiple thin plates of alternating refractive indexes. A recent report by Crookes et. al., showed that the major composition of these reflective layers is proteinaceous and is composed of a family of closely related proteins termed reflectins. These proteins have an extremely unusual and rare amino acid composition and represent a unique optical protein whose properties are inherently important for light reflection. Here we characterize the self-assembling properties of the recombinant reflectin protein. The largely hydrophobic reflectin protein is expressed as inclusion bodies and forms nanospheres when dialyzed into water. Furthermore, the recombinant protein can be assembled into a variety of morphologies to include filamentous and ribbon-like structures in solution. By utilizing the self-assembling nature of reflectin, higher order photonic structures can be fabricated.
9:00 PM - T5.15
Towards Controlling Molecular Orientation and Chirality in Adsorbed Organic Monolayers Using Liquid Crystal Solvents.
Nick Gislason 1 , Tiffany Fegurgur 1 , Calvin Murphy 1 , David Patrick 1
1 Chemistry, Western Washington University, Bellingham, Washington, United States
Show AbstractThermotropic liquid crystals (LC) are being investigated as solvents to exert orientational and chiral control over molecular packing in monolayer organic films. We report scanning tunneling microscopy (STM) studies on a series of compounds that are achiral in three-dimensions, but can become chiral when constrained to two dimensions by adsorption at a solid interface. Chiral and orientational control is achieved by depositing films on a single crystal and polycrystalline graphite substrates using a LC solvent in the presence of a strong magnetic or electric field. The field aligns the solvent, which in turn exerts an orientational influence on molecules adsorbing in the film. In some compounds studied, a single orientational and chiral configuration can be selected by aligning the axis of LC alignment with the orientation of the underlying crystalline substrate, resulting in a film composed of a single molecular orientation and chirality.
9:00 PM - T5.16
Nano-imprints of Sub-100 nm Half-pitch Using Same Photocurable Fluorinated Organic-inorganic Hybrid Material System as a Resist and a Mould Material
Woo-Soo Kim 1 , Jung-Ho Jin 1 , Byeong-Soo Bae 1
1 , Korea Advanced Institute of Science and Technology, Daejeon Korea (the Republic of)
Show Abstract Nano-imprinting of a resist material using an elastomeric mould provide attractive, low cost alternatives to photolithography and other lithographic methods, especially for applications of organic photonics and electronics. However, it is becoming increasingly clear that new materials are needed to advance nano-imprinting methods to overcome problems, arising from their contact process between a mould and a resist material. The use of elastomeric moulds like PDMS offers numerous attractive properties, as well as shortcomings such as low modulus, swelling of organics, and not enough surface tension in several lithographic techniques. The resist materials, which have been used for nano-imprints, were a mixture of some photocurable monomers that are easily curable but have some weak points, e.g., large shrinkage during UV curing, low etching resistance, contact problem with a mould, etc. Our approaches to get overcome these problems of a conventional mould as well as a resist has been to replace them with photocurable fluorinated organic-inorganic hybrid materials (fluorinated hybrimers). The photocurable hybrimers have been used for contact techniques like UV embossing and stamping for the fabrication of optical devices. In this work, we will modify fluorinated hybrimers by acrylic monomers and show the fluorinated hybrimers as optimal materials for using nano-imprinting process by fabricating a fluorinated hybrimer stamps as a new mould for the next nano-imprinting process and also as an imprinting resist material itself. The photocurable fluorinated hybrimer containing a long chain of fluorine molecules exhibits high hydrophobic contact properties, rigid mechanical properties (1.2 GPa, Modulus), and simple UV curing behavior when this is used as a mould material for nano-imprints. As a resist material, this photocurable fluorinated hybrimer shows good imprinting properties, such as low shrinkage (2~2.5 vol%) after UV curing, little evaporation during process, high etching resistance, optimal wetting characteristics, easily controllable viscosity (less than 10 cp), and low adhesion to mould and high adhesion to the underlying substrate. Finally we will demonstrate clearly imprinted pattern which has sub-100 nm half-pitch by single system of photocurable fluorinated hybrimer resist and mould without any releasing and developing steps. For an appropriate example, this large area pattern of periodic nanostructure can enhance the out-coupling efficiency of organic light emitting devices.
9:00 PM - T5.17
Fabrication of Nanoscale Structures Using Block Copolymer Templates and Supercritical Carbon Dioxide
Lei Li 1 , Hideaki Yokoyama 1 , Kenji Sugiyama 2 , Taichi Nemoto 2
1 Nanotechnology Research Institute, National Institute of Advanced Industrial Science and Technology, Tsukuba Japan, 2 Department of Organic and Polymeric Materials, Tokyo Institute of Technology, Tokyo Japan
Show AbstractBlock copolymers have been receiving increased attention as ideal candidates for nanotechnological applications because of their predictable self assemble with periods ranging 10-100nm. Here we present a novel supercritical carbon dioxide (scCO2) process to fabricate nano-scale structures in copolymer thin films containing CO2-philic blocks. Starting from a series of fluorinated block copolymer mixtures, CO2 was selectively absorbed into fluorinated blocks. In the sequent depressurization, voids were introduced in CO2-philic domains. The formed nanostructures included empty cellular, cylindrical and lamellar structures as the fluorinated content increased.The typical nanocellular structures have a spacing 27 nm and a diameter of 19 nm at 8MPa when the weight ratio of fluorinated block is 35%. The size and spacing of the such nanocells can be adjusted by changing saturation pressure. In addition, both adding low molecular weight homo-PS and lowering depressurization temperature prevent the cells from over-expansion upon depressurization and provide an uniform cell distribution with anverage diameter of 24.8 nm and standard deviation of 2.4 nm even at 20MPa pressure. By further improving the content of fluorinated composition, cylindrical structures with a diameter 20nm were formed. More voids were introduced into copolymer films so that a low refractive index value 1.2, up to 50% porosity, was achieved. Since CO2 influences on the effective volume between two blocks, the long-range order of lamellae could be produced by increasing either saturation pressures or weight ratio of fluorinated block in the copolymer mixtures. These lamellar structures are parallel to substrate with a lamellar period of around 30nm. The methodology provides an access to prepare new materials with nano-scale structures which is difficult for ordinary decomposing strategies.
9:00 PM - T5.18
Fabrication and Optical Properties of the Ordered Nanostructures Composite of Metal Particles in Anodic Porous Alumina Matrix.
Toshiaki Kondo 2 , Miyuki Tanji 1 , Futoshi Matsumoto 3 , Kazuyuki Nishio 1 3 , Hideki Masuda 1 3
2 , Japan Society for the Promotion of Science, Tokyo Japan, 1 , Tokyo Metropolitan University, Tokyo Japan, 3 , Kanagawa Academy of Science and Technology, Kanagawa Japan
Show Abstract9:00 PM - T5.19
The Study Of The Nanocontact Printing By Hydrogen Silsesquioxane Stamp.
Ming-Tse Dai 1 , Cheng-Liang Laio 1 , Leio L.W. Chen 1 , Henry J.H. Chen 3 , Sun-Zen Chen 2 , Fon-Shan Huang 1
1 Institute of Electronics Engineering, National Tsing Hua University, Hsinchu Taiwan, 3 Institute of Electrical Enineering, National Chi Nan University, Nantou Taiwan, 2 Center for Nano-Science and Technology, National Tsing Hua University, Hsinchu Taiwan
Show AbstractNanocintact printing is a simple and cost-effective method to create nano-scale patterns on substrate. The conventional stamping materials, such as dimethylsiloxane (PDMS) and polyolefin plastomer (POPS), need spin-on coated e-beam resist to fabricate the pattern. But hydrogen silsesquioxane (HSQ) is a negative tone e-beam resist and becomes porous after heat treatment. So HSQ can be applied for nano/micro-printing stamp. In this study, we fabricate HSQ stamp by using e-beam with low dose and wet etching method. The various e-beam dose, TMAH concentration, and etch rate were performed in order to determine optimum condition. HSQ were mixed with MIBK with condition is HSQ:MIBK= 2 : 1. After uniform spinning on 6 inch wafer, the HSQ was baked at 90°C 3mins or at 120oC 3mins. The e-beam lithography (Leica Weprint 200) with dose 40~400 uC/cm2 were performed on the above treated HSQ. Finally, we use TMAH (2.38~12.5%) to etch HSQ to form HSQ molds and then rinsed with DI water in order to remove residue. HSQ molds with 40nm-190nm were fabricated. For ink material, two kinds of different inks were chosen one is poly-l-lysine mixed Rhodamine. Another is aminosilane mixed CdSe/ZnS QDs. Both two inks have amine group that easy crosslink with OH bond on SiO2. The thickness of ink is about 50nm~100nm. We transfer the pattern on HSQ substrate with pressure 0.45psi at room temperature.SEM shows that HSQ line stamp with 50nm and aspect ratio ~7 has flat top and vertical sidewall. These stamps were successfully fabricated by e-beam dose 280uC/cm2 with preheat temperature at 90°C for 3 mins. We found the fidelity transfer of poly-l-lysine and aminosilan on HSQ. From the fluorescence microscope, we observed the transferred line about 250nm in orange and red respectively.
9:00 PM - T5.2
Nanothick Layer Transfer of Hydrogen-implanted Wafer by Polysilicon Sacrificial Layer.
T. -H. Lee 1 2 , C.-H. Huang 2 , Y. Y. Yang 2 , C. L. Chang 2 , H. W. Wang 2 , Y. K. Hsu 2 , S. L. Lee 1 2
1 Institute of Materials Science and Engineering, National Central University, Chung-Li City Taiwan, 2 Mechanical Engineering, National Central University, Chung-Li City Taiwan
Show AbstractSmart-Cut process, a layer transfer technique of substrate by combination of hydrogen implantation and low temperature wafer bonding techniques is one of the mainstream processes to fabricate a large area, sub-micron thick, single crystal layer on a dissimilar material structure such as silicon on insulator (SOI). Due to the mass of implanted hydrogen ions is too light to enable a nano-scale thick SOI layer under critical implant energy, the transferred silicon layer from splitting usually needs to be thinned by an additional chemical mechanical polishing process which may degrade the benefit of ion implantation process and reduce the precision and uniformity of transferred layer. For example, the transferred layer of a silicon wafer is approximate 600 nanometer thickness using hydrogen (H2) ion implantation with implant energy of 180 KeV. To obtain an 80 nanometer thick SOI layer for fully depleted IC device applications, the transferred silicon layer needs to be subtracted about 450~500 nanometer thick materials, i.e. about 80% of transferred layer. In the study, a polysilicon layer was firstly deposited prior to ion implantation step as a sacrificial layer to precisely control the final implant depth for the desirable nano-scale thickness without removing much transferred layer materials. The nano-scale thick layer transfer technique performed by polysilicon layer deposition, hydrogen ion implantation, low temperature wafer bonding, and heating treatment has been investigated. The hydrogen ion implantation was performed at energy of 180 KeV with dosage of 5X10^16 / cm^2 at room temperature after polysilicon layer of 400 nanometer was deposited on the top oxidized surface of a silicon wafer as a device wafer. Before the implanted device wafer being bonded with a handle wafer, the polysilicon layer was removed by a wet chemical etching method. The bonding strength measured by the crack opening method was achieved a surface energy of > 2000 erg/cm^2 using the oxygen plasma activated wafer bonding approach and then annealing at 200 degree centigrade for one hour. The thickness of the final transferred silicon layer measured by TEM was 90 nanometer. The splitting amorphous surface on the top of transferred layer being removed by touch polishing and then flatted by high temperature hydrogen annealing without a thinning process will be performed in the continuous steps of this study.
9:00 PM - T5.20
Effects of the Ultra Low Diluted Ceria-Based Slurry on the Planarization Characteristics of Multi-Layer Exposed Surfaces.
Kyung Ho Hwang 1 , Myung Shin Lee 1 , Young Soo Choi 1 , Geun Min Choi 1 , Yong Wook Song 1
1 R & D Division, Hynix Semiconductor Inc., Icheon-si, Kyoungki-do, Korea (the Republic of)
Show AbstractThis study, based on the ultra low diluted Ceria (CeO2) slurry chemical mechanical polishing (CMP) process, was carried on to contribute the understanding of planarization characteristics on the multi–layer exposed surfaces which denote more than two kinds of films. On increasing the device integration, the process requirements for CMP process such as perfect planarization, perfect cell-to-cell isolation and defect-free surface become more stringent. The multi-layer CMP process, which is exposed on the poly-crystalline silicon, silicon nitride (Si3N4) and various oxide layers, is especially critical in terms of polishing planarity. In the DRAM manufacturing process, employing CMP process is mandatory to isolate between storage-node contact (SNC) and bit-line contact (BLC) after gate patterning. Compared to single layer CMP process, the difference of polishing rate among the films causes micro dishing problem, which induces device integration issues. In case of the memory cell region, polishing residues can make bridge fails between adjacent electrical contacts. On the other hand, dishing at peripheral region has the problem of bit-line patterning process. This is because a low selectivity slurry (LSS) has a higher pH value than 9 , so that, it relatively leads the fast polishing rate of soft oxide film, and poly silicon film, compared to silicon nitride or other hard films.In this work, ultra low diluted ceria-based slurry was introduced to minimize CMP micro dishing effect at various films exposed surface. The slurry with a high polishing selectivity value between silicon nitride and high density plasma oxide is extensively used for planarization at shallow trench isolation (STI) process. To investigate device characteristics by use of new slurry in our study, we focused on the isolation of SNC and BLC in 80nm feature sized DRAM device. As a result, we can minimize micro-dishing effect of silicon oxide and poly-crystalline silicon at memory cell region, and silicon oxide at peripheral area. However, we point that we should carefully control the erosion of silicon nitride film at the peripheral region with a low pattern density. That is, the new slurry is strongly influenced by the pattern density of the surfaces. Also, additional slurry related issues during the 80nm feature sized DRAM device fabrication will be discussed in great detail.
9:00 PM - T5.21
One-step Fabrication of Tunable Nano-void Superlattice in Electron Beam Irradiated CaF2 with In-situ TEM Observation.
Tianhua Ding 1 , Sha Zhu 1 , Lumin Wang 1 2
1 Nuclear Engineering, University of Michigan, Ann Arbor, Michigan, United States, 2 Material Science and Engineering, University of Michigan, Ann Arbor, Michigan, United States
Show Abstract9:00 PM - T5.22
Generation and Formation Mechanism of Highly Crystalline Binary Metal Oxide Layers with Ordered 3D-mesoporosity.
Torsten Brezesinski 1 , Bernd Smarsly 1 , Markus Antonietti 1
1 , Max Planck Institute of Colloids and Interfaces, Potsdam-Golm Germany
Show Abstract9:00 PM - T5.23
Rapid Production of Nanofluidic Capillaries via Femtosecond Laser Induced Delamination of Thin Thermal Oxide Films from Si(100) Substrates.
Joel McDonald 1 3 , Vanita Mistry 2 , Katherine Ray 2 , Steven Yalisove 4 3
1 Applied Physics, University of Michigan, Ann Arbor, Michigan, United States, 3 Center for Ultrafast Optical Science, University of Michigan, Ann Arbor, Michigan, United States, 2 College of Engineering, University of Michigan, Ann Arbor, Michigan, United States, 4 Materials Science and Engineering, University of Michigan, Winston-Salem, North Carolina, United States
Show AbstractA technique to produce nanofluidic capillaries using 150 femtosecond laser pulses from an amplified Ti:sapphire laser will be presented. The technique was developed after it was discovered that under certain laser intensity conditions, single fs laser pulses could delaminate 54 to 1200 nm thick thermal oxide films on Si(100), producing isolated blisters in the film. By overlapping the blisters, linear capillaries with Gaussian like cross sections were formed on samples with 1200 nm of thermal oxide, with lateral dimension of 15 μm and a height of 300 nm. By overlapping capillaries laterally, capillaries with widths greater than 100 μm, and heights up to 4 μm were produced. The dimensions of capillaries made in the 1200 nm thermal oxide film indicate that the height of tubes is largely determined by their width, hinting that the mechanism responsible for the capillary production is relaxation of the compressive stress in the film once it is delaminated from the substrate.On samples with 1200 nm of thermal oxide, simple linear capillaries were written at speeds of 10 mm/s. The laser power used to produce the tubes was less than 1% of the total output of the laser, so that by splitting the beam into multiple paths, many capillaries can be written simultaneously on the same or different samples. Capillaries can also be produced in a bitwise fashion, in which rectangle regions of film are delaminated from the substrate and connected together to form capillaries. Utilizing the bitwise writing technique, software has been developed which allows for devices to be written with only a bitmap of the desired device required. Optimal laser and sample conditions will be presented for producing the best linear capillaries and devices via the bitwise writing technique, and examples of each will be shown. Measured capillary characteristics such as flow rates, interior surface roughness, and repeatability and consistency of the direct write approach will be presented. The laser/material interaction responsible for the production of the capillaries by delamination of the thermal oxide film from the substrate will also be discussed.
9:00 PM - T5.24
Two-Dimensional Fractal Structures Obtained on Substrates Using Polypeptides.
Laura Sowards 1 , Kristi Singh 1 2 , Lawrence Drummy 1 , Linda Kasten 1 3 , Rajesh Naik 1
1 Materials and Manufacturing Directorate, Air Force Research Laboratory, Wright-Patterson Air Force Base, Ohio, United States, 2 , UES, Inc., Dayton, Ohio, United States, 3 , University of Dayton Research Institute, Dayton, Ohio, United States
Show AbstractBiomineralization occurs in many biological organisms in order to create specialized structures composed of inorganic materials. The transformation of inorganic molecules into nano- and microstructured components is controlled in vivo by proteins. The ability of proteins to direct the assembly of nanostructured components into sophisticated functional structures at ambient conditions has motiviated intense research efforts in developing methods that mimic the recognition and nucleating capabilities found in biological systems. Polypeptides like poly-L-lysine (PLL) can be used in the precipitation of metal oxides such as titania. Here we report on the formation of fractal titania-containing structures (3%) by the addition a water-soluble titanium congugate, titanium (IV) bis(ammonium lactato) dihydroxide solution (TiBALDH) to a poly-L-lysine coated substrate. Effects of precursor and biotemplate concentration on the resulting titania structures will be examined. In this study, we have demonstrated the ability to control biomineralization reactions to produce reproducible structures formed by two-dimentional diffusion-limited aggregation (DLA). The next step is to utilize micro- or nano-patterning techniques to seed structure growth. The precice placement of molecules capable of precipitating inorganic nucleation can be exploited as a method for nano- to micro-scale device fabrication.
9:00 PM - T5.26
Ink-Jet Printing of Encapsulated Bacteria
John McGuirt 1 , Faith Coldren 1 , Nicole Levi 1 , David Carroll 1 , Elizabeth Palavecino 2
1 Physics, Center for Nanotechnology and Molecular Materials, Wake Forest University, Winston-Salem, North Carolina, United States, 2 Pathology, Wake Forest University School of Medicine, Winston-Salem, North Carolina, United States
Show AbstractInk-jet printing of the gram-negative organism Escherichia coli by other researchers onto a growth medium previously completed demonstrated that the bacteria remain viable. We are interested in extending the scope of knowledge for the effect on ink-jet printing on cellular ultrastructures. The retention of viability is useful when colony growth is desired. However, when bacteria are isolated from an infection they often exhibit characteristics that can be lost when grown in standard laboratory cultures. Ideally, individual bacteria from an infection would be printed and studied without extensive culturing or processing. We investigated the gram-positive organism Staphylococcus aureus and the glycocalyx ultrastructure that surrounds the cell. The glycocalyx is composed of polysaccharides and can either be diffuse or discrete. We used atomic force microscopy and scanning electron microscopy to compare the integrity and uniformity of S. aureus glycocalyx before and after ink-jet printing.
9:00 PM - T5.28
A Mixing Micro-fluidic System Based on Rotating Magnetic Nanowires
Hao Jing 1 , Ben Wilde 4 , Russell Taylor II 4 , Leandra Vicci 4 , Richard McLaughlin 2 , Roberto Camassa 2 , Terry Jo Leiterman 2 , Richard Superfine 3 1 4
1 Materials Science, University of North Carolina Chapel Hill, Chapel Hill, North Carolina, United States, 4 Department of Computer Science, University of North Carolina Chapel Hill, Chapel Hill, North Carolina, United States, 2 Department of Mathematics, University of North Carolina Chapel Hill, Chapel Hill, North Carolina, United States, 3 Dept. of Physics and Astronomy, University of North Carolina Chapel Hill, Chapel Hill, North Carolina, United States
Show Abstract9:00 PM - T5.29
A Novel Design Toward Understanding and Characterizing Transport Behavior of Composite Mesoporous Silica Thin Films.
Zhu Chen 1 , David Adams 2 , Michael Vasile 2 , Nanguo Liu 1 , Yingbing Jiang 1 , George Xomeritakes 1 , C. Brinker 2 1
1 , University of New Mexico, Albuquerque, New Mexico, United States, 2 , Sandia national Laboratory, Albuquerque, New Mexico, United States
Show AbstractResearch in synthetic materials with controlled transport properties has been inspired by the exquisite selectivity exhibited by natural transmembrane proteins such as ion channels (for selectively transporting ions like sodium and potassium, etc) and aquaporins (for conducting high fluxes of water and excluding ions). In this poster we focus on the transport behavior of highly ordered mesoporous silica thin films synthesized by evaporation induced silica/surfactant self-assembly (EISA). This process allows us to integrate the nanostructures into electronic and fluidic systems by simple coating or spraying procedures, facilitating the characterization of their transport behaviors. Also, the nanocomposite architecture made by this process gives precisely defined pore size, orientation and surface chemistry, allowing tailoring of the motion of molecules and ions transported across the nanochannels. To approach our final goal of understanding and characterizing the transport behavior of our materials, we designed our experiments into three steps: first, we employed focused ion beam (FIB) lithography to drill a single sub-100-nm pore on a substrate support, providing a platform enabling the characterization of trans-membrane behavior of ions/molecules. Second, we developed two EISA approaches to form cubic thin film silica mesophases spanning the FIB-drilled pore. In one approach, we adapted our aerosol-assisted EISA where fusion of liquid crystalline aerosol droplets creates a thin membrane spanning the substrate pore. In the other approach, we modified our synthetic protocol to form ultra thin (20-nm) spanning films by spin-coating. Films with pore sizes ranging from 2nm to 7nm and surface chemistries including –OH, -COOH and –NH2 terminated pore surfaces were prepared in this fashion and integrated to the FIB-drilled single pore substrate support with uniformity to allow tailoring of the motion of ions and molecules. Third, we designed an electrochemical cell in which the FIB-drilled substrates are integrated to enable the measurements of ion fluxes using standard “patch-clamp” instruments. Experiments are conducted to demonstrate the transport characteristics of our materials by measuring transmembrane ion fluxes when specific molecules such as DNA are applied, a method relevant to low cost DNA sequencing. Also, by chemically or physically blocking all but one or several membrane pores, we are attempting to measure ion and water transport in individual synthetic nanopores and compare results with natural ion and water channels.
9:00 PM - T5.30
Separation of Nanocrystal/Polymer Conjugates by HPLC.
Karl Krueger 1 , Ali Al-Somali 1 , Vicki Colvin 1
1 , Rice University, Houston, Texas, United States
Show AbstractIsolation of assembled nanostructures is an important topic in nanoscience. We demonstrate the chromatographic separation of both metal and semiconductor nanocrystals functionalized with thiol-terminated polystyrene macromolecules. Au and CdSe nanocrystals were functionalized in solution with 50k molecular weight thiol-terminated polystyrene via the grafting-to approach. By limiting the amount of polymer used, total surface coverage was not achieved resulting in a distribution of nanocrystal species with 0, 1, 2, or 3 polystyrene macromolecules bound to the nanocrystal surface. Due to the large polymer size relative to the nanocrystal, we detected differences in hydrodynamic diameter between the species and separated them using high performance size exclusion chromatography. Quantitative 1H-NMR of the collected fractions with 1,4-dioxane as an internal standard confirmed the separation.
9:00 PM - T5.31
Development of a Biological Ink for Use with Piezo Inkjet Technology.
Helen Smith 1 2 , Lawrence Brott 2 , Rajesh Naik 2
1 Department of Chemistry, University of Dayton, Dayton, Ohio, United States, 2 Air Force Research Laboratory, Materials and Manufacturing Directorate, Wright Patterson Air Force Base, Ohio, United States
Show AbstractThere is a desire to develop direct write methods for the patterning of biomolecules. Currently the most prevalent direct write methods include dip-pen nanolithography (DPN), laser-mediated direct write, and inkjet printing. Our work utilizes a unique inkjet printing system composed of a single piezo ejector linked to a linear stage via custom software. An aqueous-based biological ink can be inkjet printed onto a substrate coated with a micron-thick UV-curable monomer layer using the custom inkjet printer. Utilizing this technique, biomolecules can be permanently affixed to the substrate while also retaining their activity. A practical example involves printing a silica precipitating peptide solution onto a monomer-coated sample, curing the monomer to immobilize the peptide and then further reacting the slide with a silica precursor, yielding patterned silica nanoparticles on a flexible substrate.
9:00 PM - T5.32
Nanowire-Based Chemical Sensor System Using Microfluidic Sample Handling.
Brian Hunt 1 , Eric Wong 1 , Anita Fisher 1 , Mike Bronikowski 1 , Ed Luong 1 , Peter Willis 1 , Mihail Petkov 1
1 , JPL/Caltech, Pasadena, California, United States
Show AbstractNanowire-based chemical sensors utilize a simple and effective sensing mechanism based on the change in conductance of a semiconducting nanowire (NW) as a molecule attaches to the wire or a receptor bound to the NW. Such sensors are relevant to a wide variety of applications ranging from biomedical testing to astrobiology. Effective use of these devices requires microfluidic sample handling to enable efficient delivery of minute samples, while minimizing potential problems with electrochemical degradation of electrodes. Here we report on our work on nanowire chemical sensors utilizing carbon nanotubes (CNT) and silicon nanowires in field effect transistor configurations. The carbon nanotubes are grown in controlled locations using Fe catalyst particles and methane CVD, resulting in single-walled nanotubes spanning Mo or Ti/Au electrode gaps ranging from 100 nm to 2 microns. The Si NWs are grown by silane CVD from patterned nanoscale Au catalysts, followed by liftoff of Ti/Au electrodes. The nanowires have been integrated with a PDMS-based microfluidic sample handling system. The PDMS microchannels are patterned using standard soft lithography techniques and sealed against the device chips using a support fixture compatible with direct probe electrical testing. External valves enable selection and delivery of microliter to nanoliter sample volumes to the microfluidic channels and nanowire devices. We have demonstrated both gas and liquid phase chemical sensing using unfunctionalized CNT and Si NW devices. The liquid phase testing has been aimed at measurements of amino acids in water. Conductance measurements for arginine, aspartic acid, and tryptophan showed significant differences in the magnitude and sign of the conductance change for each amino acid as the concentrations were varied. We will also report on our ongoing efforts to functionalize Si/SiO2 nanowire surfaces to enable chemically specific detection of biomolecules of interest, via protein receptor (enzyme/antibody) binding to the respective ligand.
9:00 PM - T5.33
Electroless Gold Nanoparticle Layer Patterning on Semiconductor Surfaces
Hyuneui Lim 1 , Junghyun Noh 1 , Wan-Doo Kim 1
1 Dept. of future technology, Korea Institute of Machinery and Material, Daejon Korea (the Republic of)
Show Abstract9:00 PM - T5.34
Chemically Selective Soft X-ray Lithography
Jian Wang 1 , Adam Hitchcock 1 , Harald Stover 1 , Daniel Hernandez Cruz 1 , Tolek Tyliszczak 2
1 BIMR, McMaster University, Hamilton, Ontario, Canada, 2 Chemical Sciences, Lawrence Berkeley National Lab, Berkeley, California, United States
Show AbstractWednesday, 4/19New PosterChemically Selective Soft X-ray Lithography. Adam HitchcockCurrent sub-micron and nanolithography techniques, such as X-ray or extreme ultraviolet (EUV) projection lithography, electron or ion beam lithography, and nanoimprint (soft) lithography, have no chemically or physically selective interactions with the resist materials. Monochromatic soft X-rays (100 - 1000 eV) interact very selectively with many chemical materials, such as resist polymers. Thus, patterning with soft X-rays can be used for chemically selective lithography, which may have potential nanomanufacturing applications. Here we present some recent work toward this goal with focus on quantitative studies of soft X-ray radiation damage of polymers and optimization of both samples and procedures for chemically selective lithography. The work is performed using a scanning transmission X-ray microscope (STXM) at beamline 5.3.2 at the Advanced Light Source, Berkeley.Near edge X-ray absorption spectra (NEXAFS) and quantitative dose-damage relationships were measured for poly(methyl methacrylate) (PMMA) and polyacrylonitrile (PAN) as part of the development of chemically selective X-ray lithography. The absorption spectra are characterized by a strong π*(C≡N) absorption peak at 286.8 eV for PAN and a strong π*(C=O) absorption peak at 288.4 eV for PMMA. The critical dose for chemical change to PAN (destruction and loss of C≡N groups) is about 2~3 times larger than that for PMMA (destruction and loss of C=O groups).Chemically selective X-ray lithography was achieved by using carefully selected X-ray photon energies and radiation doses to confine the radiation damage of C≡N groups in PAN domains and C=O groups in PMMA domains. Four different polymer film systems were studied: a PAN-blend-PMMA micro phase-separated film, a PMMA-on-PAN bilayer film, poly(MMA-co-AN) copolymer film and a polycyanoacrylate homopolymer film. Energy-specific damage of C≡N in PAN at 286.8 eV and C=O in PMMA at 288.4 eV at the same (x,y) position of the sample was achieved only for the PAN/PMMA bilayer. In the last two homogenous systems similar amounts of damage to the nitrile and acrylate groups occurred at 286.8 and 288.4 eV due to the close spatial proximity of the C≡N and C=O groups. To demonstrate chemically selective lithography, several chemically selective patterns were created in the PAN/PMMA bilayer system. Radical inhibitors are shown to be effective in reducing radical migration and improving spatial resolution, currently limited by radical migration to ~100 nm. The fabrication and test of a trilayer system, which would be capable of full color lithography, is in progress and will be reported at the meeting.Research supported by NSERC (Canada), CFI, Canada Research Chair program.
9:00 PM - T5.4
Interface Structure Characterization of Vertically Aligned Carbon Nanofibers.
Yusuke Ominami 1 , Makoto Suzuki 1 , Ngo Quoc 1 3 , Kevin Mcilwrath 2 , Konrad Jarausch 2 , Alan Cassell 3 , Jun Li 3 , Cary Yang 1
1 Center for Nanostructures, Santa Clara University, Santa Clara, California, United States, 3 , Hitachi High Technologies America, Pleasanton, California, United States, 2 Center for Nanotechnology, NASA Ames Research Center, Moffett Field, California, United States
Show AbstractWe report detailed interfacial nanostructures of vertically aligned carbon nanofibers (CNFs) with various diameters using scanning transmission electron microscopy (STEM). Using plasma-enhanced chemical vapor deposition (PECVD), vertically aligned CNFs are selectively grown on a substrate comprising a narrow strip (width ~100nm) fabricated with focused ion beam (FIB). The novel sample preparation technique used for this work is ideal for highly efficient analysis of carbon nanostructures. Findings obtained from this analysis provide crucial information for the manufacturing process to tune process conditions in order to obtain favorable CNF structures for electronic and sensing applications. Because device structure plays an integral part in performance, characterization using STEM is vital to process development. Our technique is highly accurate and less time consuming than traditional TEM sample preparation. CNFs can clearly be observed on the narrow, 100nm wide strip, making these structures favorable for analysis with STEM. The diameters of CNFs range from 10nm to 100nm. We characterized the nanostructures of CNFs with STEM, focusing on the interfacial region near the base of the CNFs. The structures of stacked graphene sheets parallel to the narrow strip have been observed near the base of CNFs having diameters of 10, 20, 40, and 80nm, respectively. The evolution of these graphene stackings provides some insight into the growth mechanisms of CNFs.
9:00 PM - T5.5
A Regular Array of Polydiacetylene Vesicles Fabricated by Using Nanoshpere Lithograhpy and Selective Immobilization.
Eun Young Kim 1 , Myung Mo Sung 1
1 Chemistry, Kookmin University, Seoul Korea (the Republic of)
Show Abstract9:00 PM - T5.6
Direct Patterning of Aluminum Thin Fimls on TiO2-Coated Si Substrates by Using Metal Transfer Printing.
Yeon Hee Cho 1 , Myung Mo Sung 1
1 Chemistry, Kookmin University, Seoul Korea (the Republic of)
Show Abstract9:00 PM - T5.7
Search for Reaction Pathways of a CMOS-compatible Fabrication of Nanofluidic Channels by Means of Atomistic Computer Simulations.
Lars Roentzsch 1 , Karl-Heinz Heinig 1
1 FWIT, Research Center Rossendorf, Dresden Germany
Show AbstractNanofluidic devices are going to play an important role in miniaturization, automation and parallelization of chemical, biological, or medical systems. At present, the fabrication of microfluidic channel networks requires a large number of sophisticated processing steps. For "lab on a chip" devices, CMOS compatibility is desired in the fabrication process, additionally.In this contribution, we present potential reaction pathways of a nonconventional, however, CMOS-compatible fabrication method of nanofluidic channels and channel networks. The reaction pathways are predicted by Monte Carlo simulations which atomistically describe the evolution of a sample configuration during a thermal treatment. Referring to the "empty-space-in-silicon" formation technique (T. Sato et al., Jnp. J. Appl. Phys. 43 (2003) 12.), a Si-(100) substrate is assumed which contains isolated trenches that are arranged in a line. This approach is modified by using trenches of different depths and diameters. During thermal treatment in a low-pressure hydrogen atmosphere, migration of surface atoms leads to an overall surface minimization. Thin trenches decouple quickly from the wafer surface forming buried voids. In a self-organizing manner, neighboring voids may coalesce and, thus, they construct a buried channel. Due to their lower surface-to-volume ratio, thick trenches are more stable. They remain in contact with the wafer surface and, therefore, they may act as vertical supply and drain pipes for the buried channels. In addition, the simulations predict the formation of elementary nanochannel networks such as T-junctions, X-junctions, or H-filters. The channel surface of the whole active layer can be transformed into SiO2 by post-fabrication oxidation.
9:00 PM - T5.8
Fabrication of 2D Structured Nanowebs During Electrospinning.
Bin Ding 1 , Chunrong Li 2 , Yasuhiro Miyauchi 1 , Seimei Shiratori 1 2
1 , Keio University, Yokohama Japan, 2 , SNT Co. Ltd., Kawasaki Japan
Show AbstractWe report a new manufacturing technique for generating novel two-dimensional (2D) nanowebs among electrospun nanofibers by optimization of various processing parameters during electrospinning. The formation of the nanowebs of poly(acrylic acid) and Nylon 6 is considered due to the fast phase separation of the charged droplets in flight. The formation possibility, morphology, and area density in electrospun fiber textiles of the nanowebs are strongly affected by the ambient relative humidity, solvents, solution concentration, applied voltage, and syringe tip to collector distance (TCD). The electrospun fibers act as supporter to support the “fishnet-like” nanowebs comprised of interlinked 1D nanowires. The average diameter of the nanowires contained in nanowebs is one order of magnitude lower than that of conventional electrospun fibers. We find that relative humidity, kinds of solvents, and applied voltage are strongly correlated with the formation of nanowebs among electrospun fibers. Additionally, the pore shape and size of nanowebs, and the adhesion conditions between electrospun fiber and nanoweb can be affected by the polymer concentration, TCD, and applied voltage. The expanded applications of electrospun fibers are expected due to the formation of nanowebs, such as the nanosize controllable filters and high efficient catalysts, catalyst supporter, and sensors.
9:00 PM - T5.9
Controlling Length of Gold Nanorods and Monitoring Their Growth Mechanism Using X-ray Absorption Spectroscopy.
Ru-Shi Liu 1 , Hao Ming Chen 1 , Shu-Fen Hu 2
1 Department of Chemistry, National Taiwan University , Taipei 106 Taiwan, 2 , National Nano Device Laboratories, Hsinchu 300 Taiwan
Show AbstractA new approach to fabricate long length of gold nanorods by controlling the volume of growth solution will be reported. The shape evolutions ranging from fusiform nanoparticles to 1-D rods was observed. Increasing the addition of growth solution can control the length of nanorods. The length of rods can be extended to 2 μm, and nanorods with aspect ratios of up to ~ 70 could be obtained. Moreover, X-ray absorption spectroscopy (XAS) is applied herein to elucidate the growth mechanism of gold nanorods. The gold ions were directly reduced to gold atoms by ascorbic acid during the reaction, and then gold atoms were deposited on the surface of gold seeds that were introduced into the reaction. Extended X-ray absorption fine structure (EXAFS) confirmed the growth of gold and the environment around Au atoms over the reaction. The XAS are expected to have wide applications in the growth of gold and other related materials.
Symposium Organizers
Francesco Stellacci Massachusetts Institute of Technology
Joseph W. Perry Georgia Institute of Technology
Gregory S. Herman Hewlett-Packard Company
Rabindra Nath Das Endicott Interconnect Technologies
T6: Soft Lithography and Printing
Session Chairs
Albert Jeans
Francesco Stellacci
Thursday AM, April 20, 2006
Room 2004 (Moscone West)
9:30 AM - **T6.1
Some Recent Developments in Soft Lithography
John Rogers 1
1 , University of Illinois, Urbana, Illinois, United States
Show AbstractThis talk describes some new soft lithographic methods, including soft imprinting with molecular scale resolution, liquid immersion photolithography with conformable masks, and kinetically controlled transfer printing of solid objects. The patterning capabilities of these techniques will be illustrated through some representative applications in electronics and photonics.
10:00 AM - T6.2
Rapid Prototyping of Poly(dimethylsiloxane) (PDMS) Stamps with Electron Beam Lithography: Novel Features and Patterning Chemical Functionality.
Matthew Russell 1 , Liam Pingree 2 , Mark Hersam 2 , Tobin Marks 1 2
1 Chemistry, Northwestern University, Evanston, Illinois, United States, 2 Materials Science and Engineering, Northwestern University, Evanston, Illinois, United States
Show Abstract10:15 AM - T6.3
Influence of Low Molecular Weight PDMS Chains in PDMS-based Non-Photolithography.
Jinook Kim 1 , C.H. Lee 1 , Mikyung Park 1 , G.S. Chae 1 , In-Jae Chung 1
1 , LG.Philips LCD R &D center, Gyongki-do Korea (the Republic of)
Show AbstractWe present the compatibility of elastomeric stamp, poly(dimethylsiloxane) (PDMS), with inks for non-photolithography. This ink dependence is important in considering the lamination of hydrophilic solution on the patterned ink surface using an elastomeric stamp. We focus on an increase of the hydrophobicity of the patterned surface due to diffusion of low molecular weight (LMW) silicone polymer chains. This hydrophobicity increases as the decrease of PDMS-ink interaction parameter (c), which is correlated with the solubility parameter (d). In this study, the results can be proposed design factors of the ink for the patterned functional layer using PDMS-based lithography.
10:30 AM - T6.4
Physical Limits for the Speed and Resolution of Ink-Jet Printed Lines.
Brian Derby 1
1 School of Materials, University of Manchester, MANCHESTER United Kingdom
Show AbstractInk-jet printing can be used to manufacture precision electronic components and devices. The resolution of the printed structure depends on the size of the printed drops and the speed at which a structure can be printed depends on both the drop size and the frequency at which they are generated. Here we consider the inter-relation between these process parameters and the physical principles that operate during ink-jet printing. Ink-jet printing is considered as three distinct processes of drop generation, drop flight and drop impact. Simple dimensional analyses of these processes is shown to generate a set of limiting bounds, which can be illustrated graphically in a parameter space defined by the dimensionless Reynolds and Weber numbers to define the conditions under which drop-on-demand ink-jet printing is possible. The limiting condition for drop flight is governed by aerodynamic drag and is determined by the ratio of the fluid viscosity to that of the surrounding atmosphere. The limiting bound for drop impact (the onset of splashing) is used in conjunction with that for droplet generation to show that the fluid Reynolds number determines an upper bound for drop velocity on impact. It is further shown that simple equilibrium considerations of the requirements for droplet overlap to form lines on substrates can be used in conjunction with this upper bound for drop impact, to predict a maximum transverse velocity of the drop generator (printhead) relative to the substrate and thus the maximum speed at which a linear feature can be drawn.
10:45 AM - T6.5
Biodegradable Nano-Material Composites for Use in an Inkjet Printing System.
Nicole Levi 1 2 , Faith Coldren 1 , Baxter McQuirt 1 , David Carroll 1 2
1 Center for Nanotechnology and Molecular Materials, Department of Physics, Wake Forest University, Winston-Salem, North Carolina, United States, 2 School of Biomedical Engineering and Sciences, Virginia Tech Wake Forest University, Winston-Salem, North Carolina, United States
Show AbstractCurrent interest has lead to explorations of biodegradable materials such as collagen, elastin, poly (lactic) glycolic acid, alginates, polyethylene glycol, and many others for use in scaffolding of soft or hard tissues. Such materials are commonly manufactured using solvent casting, fiber spinning and weaving, as well as molding and pressing techniques; however, alternate methods are sought to create patterned macro- and micro- scopic structures for use as implantable cell scaffolds. It was recently discovered, by other groups, that a modified inkjet printer is a viable alternative method and, not only could biomaterials like collagen be printed, but living cells could also be printed within the structure. In such a manner, it was found that three- dimensional gel-type matrices, including viable cells, could be printed. Printing biologically compatible materials does have limitations however, including viscosity of the solution and the tendency of materials to clog the print head. To offer a wider range of clinically useful printed materials, modification of the structural integrity of printed polymeric materials should be examined. Hence, it would be ideal to incorporate nano- particles, including carbon nanotubes into polymer matrices without leading to the above- described printing dilemmas. We have evaluated pure and composite blends of the following polymers: collagen, alginate, and fibronectin, as well as blends of polyesters. Using a thermally (or piezoelectrically) driven inkjet printer may significantly impact nano-material/ polymer composites during printing. For example, nanoparticles have the ability to either crystallize or cut polymers under the appropriate heating and mechanical regimes. This may lead to clogging of the print head dependent upon the composite system chosen. Thermal gradients induced during droplet formation may result in site-specific aggregation of nano- materials which were initially well dispersed. Examination of our doped and undoped polymeric printed structures was carried out to provide an idea of morphologies and mechanical properties of the composite materials. These properties were then correlated with structural integrity in printed three dimensional structures. Surface morphology, local elastic moduli and visco-elastic response, as well as and height characteristics were determined using atomic force microscopy, confocal microscopy, and electron microscopy. The purpose behind our work was to elucidate a variety of materials that can be printed and determine the ease of working with these materials. Fundamental knowledge about materials and solvents that may be used is key to future development of the bio-printing technique. In addition to the choices of biodegradable polymers, a selection of incorporated nano-materials to enhance the structural integrity of the printed material was also evaluated.
11:30 AM - **T6.6
Nanoimprint as a Disruptive Technology.
William Tong 1 2 , Wei Wu 2 , Gun-Young Jung 2 , Zhaoning Yu 2 , Shih-Yuan Wang 2 , James Ellenson 1 , Kenneth Kramer 1 , Timothy Hostetler 1 , A Talin 3 , Blake Simmons 3 , Laura King 1 , R Williams 2
1 Advanced Materials Process Lab, TDO, Hewlett-Packard Company, Corvallis, Oregon, United States, 2 Quantum Science Research, HP Labs, Hewlett-Packard Company, Palo Alto, California, United States, 3 , Sandia National Laboratories, Livermore, California, United States
Show Abstract12:00 PM - T6.7
Supramolecular Nano-Stamping (SuNS) on Polymethylmethacrylate (PMMA).
Arum Yu 1 , Tim Savas 2 , Stefano Cabrini 3 , Enzo diFabrizio 4 , Henry I. Smith 2 , Francesco Stellacci 1
1 Materials Science and Engineerinmg, Massachusetts Institute of Technology, Cambridge, Massachusetts, United States, 2 Research Laboratory of Electronics, MIT, Cambridge, Massachusetts, United States, 3 , Laboratorio TASC Statale, Basovizza-Trieste Italy, 4 , Universita' Magna Graecia, Cantanzaro Italy
Show AbstractIndustry is always looking for novel parallel production methods that enable the fabrication of small and complex (i.e. information rich) devices. Recently, we developed a new printing technique, Supramolecular Nano-Stamping (SuNS), capable of printing soft molecules with high resolution.[1] SuNS is based on the specific interaction between a pair of complement DNA strands: a master, with features composed of single stranded DNA, can be reproduced through three simple assembly- and contact-based steps. The final product is a substrate containing the same features present in the master, and made of the complementary DNA strands. SuNS is a unique technique because it can be used to print features made of DNA strands with different sequences, simultaneously. This makes SuNS the only stamping methods able to transfer chemical information together with spatial information. Additionally, in SuNS, any printed pattern can be used as a new master to stamp other copies. In our first report,[1] SuNS was applied to print on gold substrates. Despite the initial successes in terms of resolution and efficiency, gold substrates are far from ideal. First, their mechanical properties prevent the printing on large areas due to contact related limitations. Second, the printed features are not suitable for optical applications. And finally, flat gold substrates are difficult to produce and thus expensive. Here, we present new results concerning the stamping (via SuNS) on polymethylmethacrylate (PMMA), a flexible substrate, with many advantages. PMMA is i) optically transparent, ii) insulating, and iii) inexpensive. Also, PMMA has a temperature of glass transition (1000C) that is far enough from room temperature to provide mechanical robustness but is also low enough to allow for conformal contact with a master. The use of PMMA substrates for SuNS provided a substantial improvement in printing coverage (100μm2) while still keeping high resolution (feature resolution: 50nm, point-to-point resolution: 100nm). We believe that the extension of SuNS to polymeric substrates is another step toward the fabrication of DNA micro-arrays in a massively parallel and inexpensive way.[1] Yu, A. A.; Savas, T. A.; Taylor, G. S.; Guiseppe-Elie, A.; Smith, H. I.; Stellacci, F. Nano Lett. 2005, 5, 1061-1064
12:15 PM - T6.8
High-rate Nanomanufacturing of Nanoscale Patterns and Sensors by Rapid Thermal Printing of Nano-elements-assembly onto a Plastic
Myunghwan Kim 1 , Jun Lee 1 , Ming Wei 1 , Jason Chiota 1 , Zhenghong Tao 1 , Sandip Sengupta 1 , Sivasubramanian Somu 2 , Ahmed Busnaina 2 , Carol Barry 1 , Joey Mead 1
1 Plastics Engineering, NSF Center for High-rate Nanomanufacturing , University of Massachusetts Lowell, Lowell, Massachusetts, United States, 2 NSF Center for High-rate Nanomanufacturing, Northeastern University, Boston, Massachusetts, United States
Show AbstractPolystyrene (PS) phases are thermally printed onto an immiscible poly (methylmethacrylate) (PMMA) substrate at a high rate using injection or compression molding. This approach does not require the long period of annealing to fabricate plastic periodic patterns on templates, necessary for block copolymers. Nanoscale organic (or gold) line and dot features are patterned on gold (or silicon) substrates using Dip-Pen Nanolithography, Nanoimprint, or e-beam lithography. The surfaces of the line and dot features are chemically modified to create an appropriate surface functionality by the deposition of polyelectrolytes or thiols. In a subsequent step, charged monodisperse polystyrene spheres (50 nm) are selectively assembled on the surfaces of the line and dot features (or only the substrate) via electrostatic attraction. Upon exposure to a chemical vapor, PS spheres plasticize, coalesce, and level at the top surface of line and dot features (or only the substrate). These PS phases on features are transferred to PMMA substrate using hot compression or injection molding. The thermally printed PS patterns on the PMMA plastic are examined using AFM (FMM, MFM), FE-SEM, OM, and TEM. This approach to patterning is general and can utilize various nano-elements, such as, fluorescent PS, protein conjugated PS, and colloidal iron oxide. Further studies are in progress for photonic, biosensor, and memory device application.
12:30 PM - T6.9
Directed Assembly of Conducting Polymers Using Electrostatically Addressable Templates and Pattern Transfer by Compression Molding or Solution Casting
Ming Wei 1 , zhenghong Tao 1 , Sivasubramanian Somu 2 , Myunghwan Kim 1 , Sandip Sengupta 1 , Ahmed Busnaina 2 , Carol Barry 1 , Joey Mead 1
1 Plastics Engineering, Umass Lowell, Lowell, Massachusetts, United States, 2 , Northeastern University, Boston, Massachusetts, United States
Show AbstractThe use of electrostatically addressable templates for the directed assembly of conducting polymer and pattern transfer to another polymer substrate is the focus of this work. Conducting polyaniline doped by camphor-sulfonic acid and dissolved in dimethylformamide was selectively assembled on the negative electrodes. The use of electric fields causes the deposition of polyaniline on the patterned template to occur rapidly in one-step and avoids complicated chemical methods, such as template polymerization of conductive polymer and functionalization of the substrate surface. Results indicated that the amount of deposited polyaniline was controlled by the deposition time and the applied electric field strength. After deposition, complete transfer of the templated pattern to a second substrate has been demonstrated. Transfer was accomplished by compression molding for styrene-butadiene rubber sheet and solution casting for polystyrene substrates. The simple one-step assembly of conductive polymers and facile pattern transfer make this approach promising for the fabrication of high performance flexible nanoelectronics and biosensors by high rate nanomanufacturing.
12:45 PM - T6.10
The Formation of Nanoislands by Electromolding Self-Organization Process.
Cheng-hsin Chiu 1 , Zhijun Huang 1
1 Materials Science and Engineering, National University of Singapore, Singapore Singapore
Show AbstractThe self-assembly of crystalline nanoislands on the Stranski-Krastanow (SK) film-substrate systems is a promising nanomanufacturing technique with an enormous amount of potential applications. A challenge of the technique is to control the size, shape, and site of the islands. In this talk, we propose that the controlled self-assembly of nanoislands can be realized by using a patterned electric plate to generate an electric field on the SK system consisting of a conductor film and a semi-conductor substrate; we call the approach the electromolding self-organization (EMSO) process. The capability of the EMSO process is explored by energy analysis and numerical simulation for the morphological evolution of the SK system under an electric filed. Our results show that the EMSO process can activate the self-assembly of nanoislands that are stable against size variation. By modifying the patterns on the electric plate, the EMSO process allows the sizes, shapes, and sites of the stable islands to be tailored individually, and the EMSO process has the potential to fabricate numerous shapes of nanoislands such as pyramids, pits, rings, wires, trenches, and cross junctions. The theory, the three-dimensional simulation results, and the applications of the EMSO process are presented in this talk.
T7: Self-Assembly Methods
Session Chairs
Thursday PM, April 20, 2006
Room 2004 (Moscone West)
2:30 PM - T7.1
The Formation of Anodic Aluminum Oxide Pore Array in Trench Structures via CMP Process.
Sang-Hyun Park 1 3 , Ki-Bum Kim 1 3 , Yu-Won Lee 2 , Jin-Kyu Lee 2 , Hyoung-Keun Choi 1 , Kyoung-Woo Lee 1
1 School of Materials Science and Engineering, Seoul National University, Seoul Korea (the Republic of), 3 Nano Systems Institute-NCRC, Seoul National University, Seoul Korea (the Republic of), 2 Department of Chemistry, Seoul National University, Seoul Korea (the Republic of)
Show Abstract2:45 PM - T7.2
Control over Pore Positions in Anodised Aluminium Oxide Films via Manipulation of the Surface of Pure Aluminium with a Hysitron.
Darren LeClere 1 , Brian Derby 1 , George Thompson 2
1 Manchester Materials Science Centre, Manchester University, Manchester United Kingdom, 2 Corrosion and Protection Centre, Manchester University, Manchester United Kingdom
Show Abstract3:00 PM - T7.3
Fabrication of Metal Nanohole Arrays with Straight Holes of High Aspect Ratios
Takashi Yanagishita 1 , Kazuyuki Nishio 1 2 , Hideki Masuda 1 2
1 , Kanagawa Academy of Science and Technology, Kanagawa Japan, 2 , Tokyo Metropolitan University, tokyo Japan
Show AbstractOrdered nanohole array structures with uniform-shaped and -sized holes have attracted growing interest as a key material for the preparation of several types of functional nanodevices. Anodic porous alumina, which was formed by the anodization of Al in an acidic solution, is one of the promising hole array materials due to its naturally occurring highly ordered hole array structure [1]. To expand the application fields of anodic porous alumina, we have developed a replication process for preparing metal or semiconductor nanohole arrays using anodic porous alumina templates [1,2]. However, in the previous process, it is difficult to form the ordered nanohole arrays with straight holes of high aspect ratios. In the present report, we describe the fabrication of ordered metal nanohole array with high aspect ratios by new replication process. The new process is based on the preparation of polymer pillars, both sides of which are supported by supporting layers, therefore can be maintained upright. Such nanopillar arrays can be used as the negative-type for nanohole arrays with straight holes of high aspect ratios. In the experiment, Ni nanohole arrays with high aspect ratios [3] were fabricated by electrochemical deposition. The obtained Ni nanohole array will be applied to several types of functional nanodevices. [1] H. Masuda et al. Science, 268, 1466 (1995). [2] H. Masuda et al. Jpn. J. Appl. Phys., 31, L1775 (1992). [3] T. Yanagishita et al., Adv. Mater., 17,2241 (2005).
3:15 PM - T7.4
Contacts to Gold Nanowires Arrayed in Porous Anodic Alumina Templates.
Kalapi Biswas 1 , Yexian Qin 2 , Manuel DaSilva 1 , Ron Reifenberger 2 , Timothy Sands 1 3
1 School of Materials Engineering, Purdue University, West Lafayette, Indiana, United States, 2 Department of Physics, Purdue University, West Lafayette, Indiana, United States, 3 School of Electrical and Computer Engineering, Purdue University, West Lafayette, Indiana, United States
Show AbstractNanowire array composites fabricated by electrodeposition into porous anodic alumina (PAA) templates exhibit anisotropic optical, thermal and electronic properties that cannot be achieved in homogeneous bulk or thin-film materials. The nanoscale characteristic dimensions allow the engineering of properties on the scale of the scattering lengths of phonons and electrons, and the wavelengths of phonons, electrons and photons. Potential applications of nanowire array composites include materials for thermoelectric cooling devices, nanoplasmonic optics, light-emitting diodes and a wide range of sensing devices. Common to many of these applications is the need for developing fabrication processes and measurement strategies for low-resistance ohmic contacts. In this work, contacts to Au nanowire arrays have been investigated as a model system. A procedure is demonstrated for the measurement of electrical properties of individual nanowires and arrays of nanowires grown in porous anodic alumina templates. Gold nanowires of diameter 50 nm were synthesized in PAA templates by electrodeposition. The individual wires were grown from a 100 nm platinum back electrode deposited by e-beam evaporation prior to electrodeposition. Planarization of the top of the alumina template was achieved by mechanical polishing of the array composite structure. After planarization, a uniform length of the nanowire array (typically 50nm) was exposed by selective etching of the template. The exposed nanowire tips facilitate the formation of low-resistance ohmic contacts. The structural, topographical and electrical characteristics of the nanowire array have been studied using field emission scanning electron microscopy (FESEM) and atomic force microscopy (AFM). Force (F) vs. distance (Z) and current (I) vs. distance (Z) characteristics of individual nanowires in the template were investigated using conductive AFM. An electrical contact between the Au-coated conducting AFM probe and the exposed Au nanowire tips was initiated with the application of a force of 14.6±0.6 nN. After electrical contact was established with an individual nanowire of nominal length 15 microns, the resulting I-V data showed linear behavior with a conductance of 800±30 μS corresponding to a resistivity of 1.66±0.07 x10-7 Ωm. The nanowire resistivity is about 7.5 times higher than the bulk resistivity of gold (ρbulk=2.2x10-8 Ωm). A comparison of resistivities of individual nanowires with the measurement of arrays, as well as a scheme for the extraction of the effective contact resistance will be described.
3:30 PM - **T7.5
Wafer-Scale Ordering of Nano-Materials Through Templated Self-Assembly
Carl V. Thompson 1
1 Materials Science and Engineering, M.I.T., Cambridge, Massachusetts, United States
Show Abstract We have investigated the use of lithographic templating to control self-assembly processes involving evolution of unstable structures. This leads to the ability to achieve ordering of nano-scale materials over wafer-scale areas. Two examples will be described. In both cases, templating was achieved through the use of Si surfaces patterned with pits with inverted pyramidal shapes, patterned as diperiodic arrays using interference lithography and anisotropic etching. We have investigated solid state dewetting of Au films deposited on diperiodic topography, and determined the conditions that lead to the formation of islands with controlled spacing, size, and crystallographic orientations. Deposition of films on surfaces with topography creates a related topography on the film surface, and this topography leads to capillarity-driven surface self-diffusion. Deposition on substrates with periodic topography creates surfaces that are not only unstable relative to capillarity-driven diffusion, but which will evolve through a process governed by the symmetry of the initial topography. This can lead to dewetted films, or islands, with order that reflects that of the initial topography. Ordered islands created in this way have potential direct applications and can also be used to catalyze growth of ordered arrays of wires and tubes. We have also deposited Al films on substrates with diperiodic surface topography, to bias the instability that leads to pore formation during anodization. In this case, templating can be used to control the pore spacing and ordering symmetry (square, hexagonal, or other), and use of templating also allows the use of anodization conditions to independently control pore diameters. Similar results can be obtained by direct lithographic creation of periodic topography on the Al surface. We have shown that pore formation is the result of a strain-induced instability. Evolution resulting from such instabilities can lead to formation of pores with a range of spacings, even for a fixed set of anodization conditions. As in dewetting, templating of pore formation ‘picks’ the winning spacing from this range of allowed possibilities. We have used ordered pore arrays to create ordered arrays of dots, wires, and tubes.
4:30 PM - **T7.6
Template-Assisted Self-Assembly: A Versatile Approach to Nanoscale Structures and Patterns
Younan Xia 1
1 Chemistry, University of Washington, Seattle, Washington, United States
Show AbstractI will discuss three different types of templates that have been explored in my group for generating nanoscale structures and patterns. In the first type, cavities or tranches etched in the surface of a flat substrate have been used to assemble spherical colloids into complex clusters with well-defined structures. In the second type, relif structures patterned on a surface have been used as guides to direct the assembly of alkanethiol molecules forming controllable nanoscale patterns of monolayers. In the third type, patterned electrodes have been used to direct the assembly of electrospun nanofibers into uniaxially aligned arrays or multilayered stacks. I will particularly focus on the mechanism associated with each self-assembly process.
5:00 PM - T7.7
Mechanically Biased Self-Assembly of Quantum Dots by Nanoindentation.
Curtis Taylor 1 , Ajay Malshe 3 , Eric Stach 2 , Gregory Salamo 4
1 Mechanical Engineering, Virginia Commonwealth University, Richmond, Virginia, United States, 3 Mechanical Engineering, University of Arkansas, Fayetteville, Arkansas, United States, 2 Materials Engineering , Purdue University, West Lafayette, Indiana, United States, 4 Physics, University of Arkansas, Fayetteville, Arkansas, United States
Show AbstractQuantum dots possess unique optical and electronic properties that are changing the performance paradigm of electronic and optoelectronic devices. However, the realization of some of these devices, such as, high density memory elements, crafted photonic lattices, quantum cellular automata and high efficiency arrays of light emitters and detectors hinges upon the ability to precisely control the size and location of self-assembled quantum dots and their integration across dimensional scales. Such precise control has proven to be extremely difficult because of the stochastic nature of the self-assembly process.This work discusses the development of an innovative nanopatterning technique to direct the self-assembly of nanostructures. The technique focuses on perturbing surface strain energy by nanoindentation in order to mechanically bias quantum dot nucleation. Much of the novelty in the work lies in the characterization of indents created by ultra-low load nanoindentation. Site-specific cross-sectional thinning of nanoindents (down to 100 nm in size) has been achieved using the in-situ ‘lift-out’ technique. This allowed for observation of the deformation mechanisms of GaAs at depths and dimensions for which little is known. Transmission electron microscopy (TEM) reveals that the crystal deforms solely by dislocation activity with no evidence of stacking faults, twinning, fracture, or phase transformation. It is shown that the single-phase deformation of GaAs can be well characterized and controlled, thereby allowing for subsequent single crystal growth on the indent. Growth of InAs quantum dots on indent patterns is performed using molecular beam epitaxy (MBE). The effect of indent spacing and size on the patterned growth is investigated. The structural analysis of the quantum dots including spatial ordering, size, and shape are characterized by ex-situ atomic force microscopy (AFM). Results reveal that the indent patterns clearly bias nucleation with dot structures selectively growing on top of each indent. It is speculated that the biased nucleation is due to a combination of favorable surface strain and multi-atomic step formation at the indent sites, which leads to increased adatom diffusion on the patterned area. The success of this nanopatterning technique could lead to a relatively simple and inexpensive process for the development of novel nanoelectronic-photonic device architectures.
5:15 PM - T7.8
Dynamics of Self-Assembled Quantum-Dot Pattern Evolution Under Controlled Stress Fields
Yaoyu Pang 1 , Rui Huang 1
1 Department of Aerospace Engineering and Engineering Mechanics, University of Texas at Austin, Austin, Texas, United States
Show AbstractA strained epitaxial film can form self-assembled quantum dots. We develop a nonlinear evolution equation and a spectral method to simulate the process of self-assembly over a large area, assuming surface diffusion as the dominant mechanism. Nonlinear dependence of the surface curvature and the stress field on the surface morphology is taken into account as well as a nonlinear potential function for the wetting effect. Both two-dimensional and three-dimensional simulations are conducted effectively using a spectral method. Numerical simulations show surface roughening at the initial stage and subsequent growth and coarsening of quantum dots. By varying the stress state in the film, different shapes and sizes of the quantum dots and different special ordering are obtained. The size and ordering of quantum dots can also be controlled by applying non-uniform stress fields due to the effect of substrate surface patterning and/or templates. The present modeling and simulations suggest potential means for producing large numbers of self-assembled quantum dots with uniform size and ordered patterns.
5:30 PM - T7.9
Using Self-assembly and Selective Chemical Vapor Deposition for Precise Positioning of Individual Germanium Nanoparticles on Hafnia.
Shawn Coffee 1 , Scott Stanley 1 , Wyatt Winkenwerder 1 , Davood Shahrjerdi 2 , Sanjay Banerjee 2 , John Ekerdt 1
1 Chemical Engineering, University of Texas at Austin, Austin, Texas, United States, 2 Electrical and Computer Engineering, University of Texas at Austin, Austin, Texas, United States
Show Abstract5:45 PM - T7.10
Directed Diblock Copolymer Self-Assembly Using Engineered Topologies To Drive Defect Motion.
Ricardo Ruiz 1 , Charles Black 1 , Robert Sandstrom 1
1 T.J. Watson Research Center, IBM, Yorktown Heights, New York, United States
Show AbstractSelf-organizing materials hold great promise for delineating the critical nanometer-scale elements of future integrated circuits. While self assembly provides a pathway to defining sub-lithographic dimensions, its Achilles’ heel lies in minimizing defects. Unlike lithographic processes, self assembly involves optimization of thermodynamic free energy, which can require prohibitively long equilibration times and may never reach pattern perfection. We have begun to address this intrinsic limitation by engineering surfaces to influence the assembly process. In this way we eliminate defects in the critical device areas, while driving unavoidable imperfections to predefined, non-crucial regions. We discuss this approach within the context of lamellar-phase poly(styrene-b-methylmethacrylate) diblock copolymer films, which possess excellent material characteristics for use as lithographic templates. Understanding the dynamics of pattern formation in these materials is crucial to optimizing their performance -- we use correlation length measurements of lamellar diblock copolymer domains to extract information about mechanisms of defect annihilation. We also quantify the quality of these self-assembled materials within a framework of resist performance metrics, including resist profile, line-edge roughness, and etch characteristics.