1
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Nicollier PM, Ratschow AD, Ruggeri F, Drechsler U, Hardt S, Paratore F, Knoll AW. Gate Electrodes Enable Tunable Nanofluidic Particle Traps. J Phys Chem Lett 2024; 15:4151-4157. [PMID: 38597408 DOI: 10.1021/acs.jpclett.4c00278] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/11/2024]
Abstract
The ability to control the location of nanoscale objects in liquids is essential for fundamental and applied research from nanofluidics to molecular biology. To overcome their random Brownian motion, the electrostatic fluid trap creates local minima in potential energy by shaping electrostatic interactions with a tailored wall topography. However, this strategy is inherently static; once fabricated, the potential wells cannot be modulated. Here, we propose and experimentally demonstrate that such a trap can be controlled through a buried gate electrode. We measure changes in the average escape times of nanoparticles from the traps to quantify the induced modulations of 0.7 kBT in potential energy and 50 mV in surface potential. Finally, we summarize the mechanism in a parameter-free predictive model, including surface chemistry and electrostatic fringing, that reproduces the experimental results. Our findings open a route toward real-time controllable nanoparticle traps.
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Affiliation(s)
| | - Aaron D Ratschow
- Institute for Nano- and Microfluidics, TU Darmstadt, Peter-Grünberg-Strasse 10, D-64287 Darmstadt, Germany
| | - Francesca Ruggeri
- IBM Research Europe - Zurich, Säumerstrasse 4, CH-8803 Rüschlikon, Switzerland
| | - Ute Drechsler
- IBM Research Europe - Zurich, Säumerstrasse 4, CH-8803 Rüschlikon, Switzerland
| | - Steffen Hardt
- Institute for Nano- and Microfluidics, TU Darmstadt, Peter-Grünberg-Strasse 10, D-64287 Darmstadt, Germany
| | - Federico Paratore
- IBM Research Europe - Zurich, Säumerstrasse 4, CH-8803 Rüschlikon, Switzerland
- Laboratory for Soft Materials and Interfaces, Department of Materials, ETH Zürich, Vladimir-Prelog-Weg 5, CH-8093 Zürich, Switzerland
| | - Armin W Knoll
- IBM Research Europe - Zurich, Säumerstrasse 4, CH-8803 Rüschlikon, Switzerland
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2
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Lassaline N, Thureja D, Chervy T, Petter D, Murthy PA, Knoll AW, Norris DJ. Freeform Electronic and Photonic Landscapes in Hexagonal Boron Nitride. Nano Lett 2021; 21:8175-8181. [PMID: 34591490 DOI: 10.1021/acs.nanolett.1c02625] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Atomically smooth hexagonal boron nitride (hBN) flakes have revolutionized two-dimensional (2D) optoelectronics. They provide the key substrate, encapsulant, and gate dielectric for 2D electronics while offering hyperbolic dispersion and quantum emission for photonics. The shape, thickness, and profile of these hBN flakes affect device functionality. However, researchers are restricted to simple, flat flakes, limiting next-generation devices. If arbitrary structures were possible, enhanced control over the flow of photons, electrons, and excitons could be exploited. Here, we demonstrate freeform hBN landscapes by combining thermal scanning-probe lithography and reactive-ion etching to produce previously unattainable flake structures with surprising fidelity. We fabricate photonic microelements (phase plates, grating couplers, and lenses) and show their straightforward integration, constructing a high-quality optical microcavity. We then decrease the length scale to introduce Fourier surfaces for electrons, creating sophisticated Moiré patterns for strain and band-structure engineering. These capabilities generate opportunities for 2D polaritonics, twistronics, quantum materials, and deep-ultraviolet devices.
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Affiliation(s)
- Nolan Lassaline
- Optical Materials Engineering Laboratory, Department of Mechanical and Process Engineering, ETH Zurich, 8092 Zurich, Switzerland
| | - Deepankur Thureja
- Optical Materials Engineering Laboratory, Department of Mechanical and Process Engineering, ETH Zurich, 8092 Zurich, Switzerland
- Quantum Photonics Group, Department of Physics, ETH Zurich, 8092 Zurich, Switzerland
| | - Thibault Chervy
- Quantum Photonics Group, Department of Physics, ETH Zurich, 8092 Zurich, Switzerland
- Physics and Informatics Laboratories, NTT Research, Inc., Sunnyvale, California 94085, United States
| | - Daniel Petter
- Optical Materials Engineering Laboratory, Department of Mechanical and Process Engineering, ETH Zurich, 8092 Zurich, Switzerland
| | - Puneet A Murthy
- Quantum Photonics Group, Department of Physics, ETH Zurich, 8092 Zurich, Switzerland
| | | | - David J Norris
- Optical Materials Engineering Laboratory, Department of Mechanical and Process Engineering, ETH Zurich, 8092 Zurich, Switzerland
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3
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Gottlieb S, Pigard L, Ryu YK, Lorenzoni M, Evangelio L, Fernández-Regúlez M, Rawlings CD, Spieser M, Perez-Murano F, Müller M, Knoll AW. Thermal Imaging of Block Copolymers with Sub-10 nm Resolution. ACS Nano 2021; 15:9005-9016. [PMID: 33938722 DOI: 10.1021/acsnano.1c01820] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Thermal silicon probes have demonstrated their potential to investigate the thermal properties of various materials at high resolution. However, a thorough assessment of the achievable resolution is missing. Here, we present a probe-based thermal-imaging technique capable of providing sub-10 nm lateral resolution at a sub-10 ms pixel rate. We demonstrate the resolution by resolving microphase-separated PS-b-PMMA block copolymers that self-assemble in 11 to 19 nm half-period lamellar structures. We resolve an asymmetry in the heat flux signal at submolecular dimensions and assess the ratio of heat flux into both polymers in various geometries. These observations are quantitatively compared with coarse-grained molecular simulations of energy transport that reveal an enhancement of transport along the macromolecular backbone and a Kapitza resistance at the internal interfaces of the self-assembled structure. This comparison discloses a tip-sample contact radius of a ≈ 4 nm and identifies combinations of enhanced intramolecular transport and Kapitza resistance.
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Affiliation(s)
- Steven Gottlieb
- Instituto de Microelectrónica de Barcelona (IMB-CNM, CSIC), Carrer dels Tillers s/n, 08193 Bellaterra, Barcelona, Spain
| | - Louis Pigard
- Institute for Theoretical Physics, Georg-August-University, 37077 Göttingen, Germany
| | - Yu Kyoung Ryu
- IBM Research - Zurich, Säumerstrasse 4, 8803 Rüschlikon, Switzerland
| | - Matteo Lorenzoni
- Instituto de Microelectrónica de Barcelona (IMB-CNM, CSIC), Carrer dels Tillers s/n, 08193 Bellaterra, Barcelona, Spain
| | - Laura Evangelio
- Instituto de Microelectrónica de Barcelona (IMB-CNM, CSIC), Carrer dels Tillers s/n, 08193 Bellaterra, Barcelona, Spain
| | - Marta Fernández-Regúlez
- Instituto de Microelectrónica de Barcelona (IMB-CNM, CSIC), Carrer dels Tillers s/n, 08193 Bellaterra, Barcelona, Spain
| | - Colin D Rawlings
- IBM Research - Zurich, Säumerstrasse 4, 8803 Rüschlikon, Switzerland
| | - Martin Spieser
- SwissLitho AG, Technoparkstrasse 1, 8805 Zürich, Switzerland
| | - Francesc Perez-Murano
- Instituto de Microelectrónica de Barcelona (IMB-CNM, CSIC), Carrer dels Tillers s/n, 08193 Bellaterra, Barcelona, Spain
| | - Marcus Müller
- Institute for Theoretical Physics, Georg-August-University, 37077 Göttingen, Germany
| | - Armin W Knoll
- IBM Research - Zurich, Säumerstrasse 4, 8803 Rüschlikon, Switzerland
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4
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Liu X, Sachan AK, Howell ST, Conde-Rubio A, Knoll AW, Boero G, Zenobi R, Brugger J. Thermomechanical Nanostraining of Two-Dimensional Materials. Nano Lett 2020; 20:8250-8257. [PMID: 33030906 PMCID: PMC7662931 DOI: 10.1021/acs.nanolett.0c03358] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/18/2020] [Revised: 09/27/2020] [Indexed: 05/07/2023]
Abstract
Local bandgap tuning in two-dimensional (2D) materials is of significant importance for electronic and optoelectronic devices but achieving controllable and reproducible strain engineering at the nanoscale remains a challenge. Here, we report on thermomechanical nanoindentation with a scanning probe to create strain nanopatterns in 2D transition metal dichalcogenides and graphene, enabling arbitrary patterns with a modulated bandgap at a spatial resolution down to 20 nm. The 2D material is in contact via van der Waals interactions with a thin polymer layer underneath that deforms due to the heat and indentation force from the heated probe. Specifically, we demonstrate that the local bandgap of molybdenum disulfide (MoS2) is spatially modulated up to 10% and is tunable up to 180 meV in magnitude at a linear rate of about -70 meV per percent of strain. The technique provides a versatile tool for investigating the localized strain engineering of 2D materials with nanometer-scale resolution.
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Affiliation(s)
- Xia Liu
- Microsystems
Laboratory, École Polytechnique Fédérale
de Lausanne (EPFL), 1015 Lausanne, Switzerland
| | - Amit Kumar Sachan
- Department
of Chemistry and Applied Biosciences, ETH
Zurich, 8093 Zurich, Switzerland
| | - Samuel Tobias Howell
- Microsystems
Laboratory, École Polytechnique Fédérale
de Lausanne (EPFL), 1015 Lausanne, Switzerland
| | - Ana Conde-Rubio
- Microsystems
Laboratory, École Polytechnique Fédérale
de Lausanne (EPFL), 1015 Lausanne, Switzerland
| | - Armin W. Knoll
- IBM
Research - Zurich, Säumerstrasse
4, 8803 Rüschlikon, Switzerland
| | - Giovanni Boero
- Microsystems
Laboratory, École Polytechnique Fédérale
de Lausanne (EPFL), 1015 Lausanne, Switzerland
| | - Renato Zenobi
- Department
of Chemistry and Applied Biosciences, ETH
Zurich, 8093 Zurich, Switzerland
| | - Jürgen Brugger
- Microsystems
Laboratory, École Polytechnique Fédérale
de Lausanne (EPFL), 1015 Lausanne, Switzerland
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5
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Abstract
Accurate deposition of nanoparticles at defined positions on a substrate is still a challenging task, because it requires simultaneously stable long-range transport and attraction to the target site and precise short-range orientation and deposition. Here we present a method based on geometry-induced energy landscapes in a nanofluidic slit for particle manipulation: Brownian motors or electro-osmotic flows are used for particle delivery to the target area. At the target site, electrostatic trapping localizes and orients the particles. Finally, reducing the gap distance of the slit leads sequentially to a focusing of the particle position and a jump into adhesive contact by several nanometers. For 60 nm gold spheres, we obtain a placement accuracy of 8 nm. The versatility of the method is demonstrated further by a stacked assembly of nanorods and the directed deposition of InAs nanowires.
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Affiliation(s)
- Stefan Fringes
- IBM Research - Zurich , Säumerstrasse 4 , 8803 Rüschlikon , Switzerland
| | - C Schwemmer
- IBM Research - Zurich , Säumerstrasse 4 , 8803 Rüschlikon , Switzerland
| | - Colin D Rawlings
- IBM Research - Zurich , Säumerstrasse 4 , 8803 Rüschlikon , Switzerland
| | - Armin W Knoll
- IBM Research - Zurich , Säumerstrasse 4 , 8803 Rüschlikon , Switzerland
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6
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Rawlings C, Ryu YK, Rüegg M, Lassaline N, Schwemmer C, Duerig U, Knoll AW, Durrani Z, Wang C, Liu D, Jones ME. Fast turnaround fabrication of silicon point-contact quantum-dot transistors using combined thermal scanning probe lithography and laser writing. Nanotechnology 2018; 29:505302. [PMID: 30248025 DOI: 10.1088/1361-6528/aae3df] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
Abstract
The fabrication of high-performance solid-state silicon quantum-devices requires high resolution patterning with minimal substrate damage. We have fabricated room temperature (RT) single-electron transistors (SETs) based on point-contact tunnel junctions using a hybrid lithography tool capable of both high resolution thermal scanning probe lithography and high throughput direct laser writing. The best focal z-position and the offset of the tip- and the laser-writing positions were determined in situ with the scanning probe. We demonstrate <100 nm precision in the registration between the high resolution and high throughput lithographies. The SET devices were fabricated on degenerately doped n-type >1020/cm3 silicon on insulator chips using a CMOS compatible geometric oxidation process. The characteristics of the three devices investigated were dominated by the presence of Si nanocrystals or phosphorous atoms embedded within the SiO2, forming quantum dots (QDs). The small size and strong localisation of electrons on the QDs facilitated SET operation even at RT. Temperature measurements showed that in the range 300 K > T > ∼100 K, the current flow was thermally activated but at <100 K, it was dominated by tunnelling.
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Affiliation(s)
- Colin Rawlings
- IBM Research-Zurich, Saeumerstrasse 4, 8803 Rueschlikon, Switzerland
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7
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Marneffe JFD, Chan BT, Spieser M, Vereecke G, Naumov S, Vanhaeren D, Wolf H, Knoll AW. Conversion of a Patterned Organic Resist into a High Performance Inorganic Hard Mask for High Resolution Pattern Transfer. ACS Nano 2018; 12:11152-11160. [PMID: 30481961 DOI: 10.1021/acsnano.8b05596] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
Abstract
Polyphthalaldehyde is a self-developing resist material for electron beam and thermal scanning probe lithography (t-SPL). Removing the resist in situ (during the lithography process itself) simplifies processing and enables direct pattern inspection, however, at the price of a low etch resistance of the resist. To convert the material into a etch resistant hard mask, we study the selective cyclic infiltration of trimethyl-aluminum (TMA)/water into polyphthalaldehyde. It is found that TMA diffuses homogeneously through the resist, leading to material expansion and formation of aluminum oxide concurrent to the exposure to water and the degradation of the polyphthalaldehyde polymer. The plasma etch resistance of the infiltrated resist is significantly improved, as well as its stability. Using a silicon substrate coated with 13 nm silicon nitride and 7 nm cross-linked polystyrene, high resolution polyphthalaldehyde patterning is performed using t-SPL. After TMA/H2O infiltration, it is demonstrated that pattern transfer into silicon can be achieved with good fidelity for structures as small as 10 nm, enabling >10× amplification and low surface roughness. The presented results demonstrate a simplified use of polyphthalaldehyde resist, targeting feature scales at nanometer range, and suggest that trimethyl-aluminum infiltration can be applied to other resist-based lithography techniques.
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Affiliation(s)
| | | | | | | | - Sergej Naumov
- Leibniz Institute of Surface Engineering - IOM , Leipzig 04318 , Germany
| | | | - Heiko Wolf
- IBM Research - Zurich , Rüschlikon CH-8803 , Switzerland
| | - Armin W Knoll
- IBM Research - Zurich , Rüschlikon CH-8803 , Switzerland
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8
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Schwemmer C, Fringes S, Duerig U, Ryu YK, Knoll AW. Experimental Observation of Current Reversal in a Rocking Brownian Motor. Phys Rev Lett 2018; 121:104102. [PMID: 30240236 DOI: 10.1103/physrevlett.121.104102] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/30/2018] [Revised: 07/13/2018] [Indexed: 05/11/2023]
Abstract
A reversal of the particle current in overdamped rocking Brownian motors was predicted more than 20 years ago; however, an experimental verification and a deeper insight into this noise-driven mechanism remained elusive. Here, we investigate the high-frequency behavior of a rocking Brownian motor for 60 nm gold spheres based on electrostatic interaction in a 3D-shaped nanofluidic slit and electro-osmotic forcing of the particles. We measure the particle probability density in situ with 10 nm spatial and 250 μs temporal resolution and compare it with theory. At a driving frequency of 250 Hz, we observe a current reversal that can be traced to the asymmetric and increasingly static probability density at high frequencies.
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Affiliation(s)
| | - Stefan Fringes
- IBM Research GmbH, Säumerstrasse 4, 8803 Rüschlikon, Switzerland
- Department of Physics, University of Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland
| | - Urs Duerig
- IBM Research GmbH, Säumerstrasse 4, 8803 Rüschlikon, Switzerland
- SwissLitho AG, Technoparkstrasse 1, 8005 Zürich, Switzerland
| | - Yu Kyoung Ryu
- IBM Research GmbH, Säumerstrasse 4, 8803 Rüschlikon, Switzerland
| | - Armin W Knoll
- IBM Research GmbH, Säumerstrasse 4, 8803 Rüschlikon, Switzerland
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9
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Skaug MJ, Schwemmer C, Fringes S, Rawlings CD, Knoll AW. Nanofluidic rocking Brownian motors. Science 2018; 359:1505-1508. [PMID: 29599239 DOI: 10.1126/science.aal3271] [Citation(s) in RCA: 73] [Impact Index Per Article: 12.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2017] [Accepted: 02/01/2018] [Indexed: 12/14/2022]
Abstract
Control and transport of nanoscale objects in fluids is challenging because of the unfavorable scaling of most interaction mechanisms to small length scales. We designed energy landscapes for nanoparticles by accurately shaping the geometry of a nanofluidic slit and exploiting the electrostatic interaction between like-charged particles and walls. Directed transport was performed by combining asymmetric potentials with an oscillating electric field to achieve a rocking Brownian motor. Using gold spheres 60 nanometers in diameter, we investigated the physics of the motor with high spatiotemporal resolution, enabling a parameter-free comparison with theory. We fabricated a sorting device that separates 60- and 100-nanometer particles in opposing directions within seconds. Modeling suggests that the device separates particles with a radial difference of 1 nanometer.
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10
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Fringes S, Holzner F, Knoll AW. The nanofluidic confinement apparatus: studying confinement-dependent nanoparticle behavior and diffusion. Beilstein J Nanotechnol 2018; 9:301-310. [PMID: 29441273 PMCID: PMC5789440 DOI: 10.3762/bjnano.9.30] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/21/2017] [Accepted: 01/12/2018] [Indexed: 05/25/2023]
Abstract
The behavior of nanoparticles under nanofluidic confinement depends strongly on their distance to the confining walls; however, a measurement in which the gap distance is varied is challenging. Here, we present a versatile setup for investigating the behavior of nanoparticles as a function of the gap distance, which is controlled to the nanometer. The setup is designed as an open system that operates with a small amount of dispersion of ≈20 μL, permits the use of coated and patterned samples and allows high-numerical-aperture microscopy access. Using the tool, we measure the vertical position (termed height) and the lateral diffusion of 60 nm, charged, Au nanospheres as a function of confinement between a glass surface and a polymer surface. Interferometric scattering detection provides an effective particle illumination time of less than 30 μs, which results in lateral and vertical position detection accuracy ≈10 nm for diffusing particles. We found the height of the particles to be consistently above that of the gap center, corresponding to a higher charge on the polymer substrate. In terms of diffusion, we found a strong monotonic decay of the diffusion constant with decreasing gap distance. This result cannot be explained by hydrodynamic effects, including the asymmetric vertical position of the particles in the gap. Instead we attribute it to an electroviscous effect. For strong confinement of less than 120 nm gap distance, we detect the onset of subdiffusion, which can be correlated to the motion of the particles along high-gap-distance paths.
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Affiliation(s)
- Stefan Fringes
- IBM Research - Zurich, Säumerstr. 4, 8803 Rüschlikon, Switzerland
- Department of Chemistry, University of Zurich, Winterthurerstrasse 190, CH 8057 Zürich, Switzerland
| | - Felix Holzner
- IBM Research - Zurich, Säumerstr. 4, 8803 Rüschlikon, Switzerland
- SwissLitho AG, Technoparkstrasse 1, 8005 Zurich, Switzerland
| | - Armin W Knoll
- IBM Research - Zurich, Säumerstr. 4, 8803 Rüschlikon, Switzerland
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11
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Carroll K, Knoll AW, Wolf H, Duerig U. Explaining the Transition from Diffusion Limited to Reaction Limited Surface Assembly of Molecular Species through Spatial Variations. Langmuir 2018; 34:73-80. [PMID: 29237260 PMCID: PMC5763283 DOI: 10.1021/acs.langmuir.7b03050] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
Surface assembly is often decomposed into two classes: diffusion and reaction limited processes. The transition between the two cases is complex because the dynamics are so different. In this article, we simulate, explain, and experimentally discuss the evolution of the spatial distribution for surface assemblies with diffusion limited and reaction limited processes. Explicitly, we demonstrate that diffusion limited and reaction limited processes show some temporal differences, but more importantly, we show that the spatial arrangements are different enough to discriminate between the two cases. Using fundamental properties, such as the diffusion constant, we calculate the evolution of the spatial profile and derive from physical, heuristic models the assembly rate for reaction and diffusion limited processes based on the individual particle's interactions with the surface. Finally, we confirm the spatial profile differences between diffusion and reaction limited cases by experimentally measuring the surface assembly between two molecules of similar size, but having different assembly routes. Unique to our description is that we have derived and simulated everything through the particle picture in place of ensemble descriptions such as the diffusion equation, and we show the equivalence between our heuristic formulas and those derived from the diffusion equation.
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12
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Ryu Cho YK, Rawlings CD, Wolf H, Spieser M, Bisig S, Reidt S, Sousa M, Khanal SR, Jacobs TDB, Knoll AW. Sub-10 Nanometer Feature Size in Silicon Using Thermal Scanning Probe Lithography. ACS Nano 2017; 11:11890-11897. [PMID: 29083870 PMCID: PMC5746844 DOI: 10.1021/acsnano.7b06307] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/05/2017] [Accepted: 10/30/2017] [Indexed: 05/20/2023]
Abstract
High-resolution lithography often involves thin resist layers which pose a challenge for pattern characterization. Direct evidence that the pattern was well-defined and can be used for device fabrication is provided if a successful pattern transfer is demonstrated. In the case of thermal scanning probe lithography (t-SPL), highest resolutions are achieved for shallow patterns. In this work, we study the transfer reliability and the achievable resolution as a function of applied temperature and force. Pattern transfer was reliable if a pattern depth of more than 3 nm was reached and the walls between the patterned lines were slightly elevated. Using this geometry as a benchmark, we studied the formation of 10-20 nm half-pitch dense lines as a function of the applied force and temperature. We found that the best pattern geometry is obtained at a heater temperature of ∼600 °C, which is below or close to the transition from mechanical indentation to thermal evaporation. At this temperature, there still is considerable plastic deformation of the resist, which leads to a reduction of the pattern depth at tight pitch and therefore limits the achievable resolution. By optimizing patterning conditions, we achieved 11 nm half-pitch dense lines in the HM8006 transfer layer and 14 nm half-pitch dense lines and L-lines in silicon. For the 14 nm half-pitch lines in silicon, we measured a line edge roughness of 2.6 nm (3σ) and a feature size of the patterned walls of 7 nm.
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Affiliation(s)
| | - Colin D. Rawlings
- IBM
Research Zurich, Säumerstrasse
4, 8803 Rüschlikon, Switzerland
- SwissLitho
AG, Technoparkstrasse
1, 8005 Zurich, Switzerland
| | - Heiko Wolf
- IBM
Research Zurich, Säumerstrasse
4, 8803 Rüschlikon, Switzerland
| | - Martin Spieser
- SwissLitho
AG, Technoparkstrasse
1, 8005 Zurich, Switzerland
| | - Samuel Bisig
- SwissLitho
AG, Technoparkstrasse
1, 8005 Zurich, Switzerland
| | - Steffen Reidt
- IBM
Research Zurich, Säumerstrasse
4, 8803 Rüschlikon, Switzerland
| | - Marilyne Sousa
- IBM
Research Zurich, Säumerstrasse
4, 8803 Rüschlikon, Switzerland
| | - Subarna R. Khanal
- University
of Pittsburgh, Pittsburgh, Pennsylvania 15261, United States
| | | | - Armin W. Knoll
- IBM
Research Zurich, Säumerstrasse
4, 8803 Rüschlikon, Switzerland
- E-mail:
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13
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Carroll KM, Rawlings C, Zhang Y, Knoll AW, Marder SR, Wolf H, Duerig U. Testing the Equivalence between Spatial Averaging and Temporal Averaging in Highly Dilute Solutions. Langmuir 2017; 33:14539-14547. [PMID: 29206465 DOI: 10.1021/acs.langmuir.7b02730] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/10/2023]
Abstract
Diffusion relates the flux of particles to the local gradient of the particle density in a deterministic way. The question arises as to what happens when the particle density is so low that the local gradient becomes an ill-defined concept. The dilemma was resolved early last century by analyzing the average motion of particles subject to random forces whose magnitude is such that the particles are always in thermal equilibrium with their environment. The diffusion dynamics is now described in terms of the probability density of finding a particle at some position and time and the probabilistic flux density, which is proportional to the gradient of the probability density. In a time average sense, the system thus behaves exactly like the ensemble average. Here, we report on an experimental method and test this fundamental equivalence principle in statistical physics. In the experiment, we study the flux distribution of 20 nm radius polystyrene particles impinging on a circular sink of micrometer dimensions. The particle concentration in the water suspension is approximately 1 particle in a volume element of the dimension of the sink. We demonstrate that the measured flux density is exactly described by the solution of the diffusion equation of an infinite system, and the flux statistics obeys a Poissonian distribution as expected for a Markov process governing the random walk of noninteracting particles. We also rigorously show that a finite system behaves like an infinite system for very long times despite the fact that a finite system converges to a zero flux empty state.
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Affiliation(s)
- Keith M Carroll
- IBM Research-Zurich , Saumerstrasse 4, 8803 Ruschlikon, Switzerland
| | - Colin Rawlings
- IBM Research-Zurich , Saumerstrasse 4, 8803 Ruschlikon, Switzerland
| | - Yadong Zhang
- School of Chemistry and Biochemistry, Georgia Institute of Technology , 901 Atlantic Drive, Atlanta, Georgia 30332-0400, United States
| | - Armin W Knoll
- IBM Research-Zurich , Saumerstrasse 4, 8803 Ruschlikon, Switzerland
| | - Seth R Marder
- School of Chemistry and Biochemistry, Georgia Institute of Technology , 901 Atlantic Drive, Atlanta, Georgia 30332-0400, United States
| | - Heiko Wolf
- IBM Research-Zurich , Saumerstrasse 4, 8803 Ruschlikon, Switzerland
| | - Urs Duerig
- IBM Research-Zurich , Saumerstrasse 4, 8803 Ruschlikon, Switzerland
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14
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Gottlieb S, Lorenzoni M, Evangelio L, Fernández-Regúlez M, Ryu YK, Rawlings C, Spieser M, Knoll AW, Perez-Murano F. Thermal scanning probe lithography for the directed self-assembly of block copolymers. Nanotechnology 2017; 28:175301. [PMID: 28374684 DOI: 10.1088/1361-6528/aa673c] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Thermal scanning probe lithography (t-SPL) is applied to the fabrication of chemical guiding patterns for directed self-assembly (DSA) of block copolymers (BCP). The two key steps of the overall process are the accurate patterning of a poly(phthalaldehyde) resist layer of only 3.5 nm thickness, and the subsequent oxygen-plasma functionalization of an underlying neutral poly(styrene-random-methyl methacrylate) brush layer. We demonstrate that this method allows one to obtain aligned line/space patterns of poly(styrene-block-methyl methacrylate) BCP of 18.5 and 11.7 nm half-pitch. Defect-free alignment has been demonstrated over areas of tens of square micrometres. The main advantages of t-SPL are the absence of proximity effects, which enables the realization of patterns with 10 nm resolution, and its compatibility with standard DSA methods. In the brush activation step by oxygen-plasma exposure, we observe swelling of the brush. This effect is discussed in terms of the chemical reactions occurring in the exposed areas. Our results show that t-SPL can be a suitable method for research activities in the field of DSA, in particular for low-pitch, high-χ BCP to achieve sub-10 nm line/space patterns.
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Affiliation(s)
- S Gottlieb
- Instituto de Microelectrónica de Barcelona IMB-CNM, CSIC, E-08193 Bellaterra, Barcelona, Spain
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15
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Rawlings C, Wolf H, Hedrick JL, Coady DJ, Duerig U, Knoll AW. Accurate Location and Manipulation of Nanoscaled Objects Buried under Spin-Coated Films. ACS Nano 2015; 9:6188-95. [PMID: 26046586 DOI: 10.1021/acsnano.5b01485] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Detection and precise localization of nanoscale structures buried beneath spin-coated films are highly valuable additions to nanofabrication technology. In principle, the topography of the final film contains information about the location of the buried features. However, it is generally believed that the relation is masked by flow effects, which lead to an upstream shift of the dry film's topography and render precise localization impossible. Here we demonstrate, theoretically and experimentally, that the flow-shift paradigm does not apply at the submicrometer scale. Specifically, we show that the resist topography is accurately obtained from a convolution operation with a symmetric Gaussian kernel whose parameters solely depend on the resist characteristics. We exploit this finding for a 3 nm precise overlay fabrication of metal contacts to an InAs nanowire with a diameter of 27 nm using thermal scanning probe lithography.
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Affiliation(s)
| | - Heiko Wolf
- †IBM Research - Zurich, Rueschlikon 8803, Switzerland
| | - James L Hedrick
- ‡IBM Research - Almaden, San Jose, California 95120, United States
| | - Daniel J Coady
- ‡IBM Research - Almaden, San Jose, California 95120, United States
| | - Urs Duerig
- †IBM Research - Zurich, Rueschlikon 8803, Switzerland
| | - Armin W Knoll
- †IBM Research - Zurich, Rueschlikon 8803, Switzerland
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16
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Koren E, Knoll AW, Lörtscher E, Duerig U. Direct experimental observation of stacking fault scattering in highly oriented pyrolytic graphite meso-structures. Nat Commun 2014; 5:5837. [PMID: 25510583 DOI: 10.1038/ncomms6837] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2014] [Accepted: 11/11/2014] [Indexed: 11/09/2022] Open
Abstract
Stacking fault defects are thought to be the root cause for many of the anomalous transport phenomena seen in high-quality graphite samples. In stark contrast to their importance, direct observation of stacking faults by diffractive techniques has remained elusive due to fundamental experimental difficulties. Here we show that the stacking fault density and resistance can be measured by analyzing the non-Gaussian scatter observed in the c-axis resistivity of mesoscopic graphite structures. We also show that the deviation from Ohmic conduction seen at high electrical field strength can be fit to a thermally activated transport model, which accurately reproduces the stacking fault density inferred from the statistical analysis. From our measurements, we conclude that the c-axis resistivity is entirely determined by the stacking fault resistance, which is orders of magnitude larger than the inter-layer resistance expected from a Drude model.
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Affiliation(s)
- E Koren
- IBM Research-Zurich, Säumerstrasse 4, 8803 Rüschlikon, Switzerland
| | - A W Knoll
- IBM Research-Zurich, Säumerstrasse 4, 8803 Rüschlikon, Switzerland
| | - E Lörtscher
- IBM Research-Zurich, Säumerstrasse 4, 8803 Rüschlikon, Switzerland
| | - U Duerig
- IBM Research-Zurich, Säumerstrasse 4, 8803 Rüschlikon, Switzerland
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17
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Abstract
The nanoscale control afforded by scanning probe microscopes has prompted the development of a wide variety of scanning-probe-based patterning methods. Some of these methods have demonstrated a high degree of robustness and patterning capabilities that are unmatched by other lithographic techniques. However, the limited throughput of scanning probe lithography has prevented its exploitation in technological applications. Here, we review the fundamentals of scanning probe lithography and its use in materials science and nanotechnology. We focus on robust methods, such as those based on thermal effects, chemical reactions and voltage-induced processes, that demonstrate a potential for applications.
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Affiliation(s)
- Ricardo Garcia
- Instituto de Ciencia de Materiales de Madrid, CSIC, Sor Juana Inés de la Cruz 3. 28049 Madrid, Spain
| | - Armin W Knoll
- IBM Research - Zurich, Saeumerstr. 4, 8803 Rueschlikon, Switzerland
| | - Elisa Riedo
- School of Physics, Georgia Institute of Technology, Atlanta, Georgia 30332-0400, USA
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Stenbock-Fermor A, Knoll AW, Böker A, Tsarkova L. Enhancing Ordering Dynamics in Solvent-Annealed Block Copolymer Films by Lithographic Hard Mask Supports. Macromolecules 2014. [DOI: 10.1021/ma500561q] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Affiliation(s)
- Anja Stenbock-Fermor
- DWI—Leibniz-Institut
für Interaktive Materialien, Forckenbeckstraße 50, 52056, Aachen Germany
| | - Armin W. Knoll
- IBM Research—Zurich, Säumerstrasse 4, CH-8803 Rüschlikon, Switzerland
| | - Alexander Böker
- DWI—Leibniz-Institut
für Interaktive Materialien, Forckenbeckstraße 50, 52056, Aachen Germany
| | - Larisa Tsarkova
- DWI—Leibniz-Institut
für Interaktive Materialien, Forckenbeckstraße 50, 52056, Aachen Germany
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Abstract
Sliding friction between a silicon tip and a polymer bilayer system consisting of a polystyrene (PS) film covered with a few-nanometers-thick capping layer of hard plasma polymer is studied using friction force microscopy. The system was chosen to enable subsurface dissipation channels to be distinguished from surface friction. Frictional energy dissipation in the underlayer can be identified through the kinetics of the polymer relaxation modes that we measured using nanoscale friction experiments as a function of sample temperature, scanning velocity, and applied load. We found a strong nonlinear increase in friction as a function of applied load around the glass-transition temperature of the PS underlayer. This behavior is a clear signature of frictional dissipation occurring in the volume of the polystyrene layer, well below the surface of the sample. The time-temperature kinetics associated with frictional energy dissipation into the PS was found to be in agreement with the known material properties of PS. Moreover, the data was found to support the hypothesis that the observed friction can be understood as the sum of friction resulting from the relaxation process in the polymer underlayer induced by stress due to the sliding of the tip and a second term associated with dissipation due to sliding friction on the capping layer.
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Affiliation(s)
- Lars Jansen
- Physikalisches Institut, Westfälische Wilhelms-Universität Münster , Wilhelm-Klemm-Str. 10, 48149 Münster, Germany
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20
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Abstract
In spite of the long history of atomic force microscopy (AFM) imaging of soft materials such as polymers, little is known about the detailed effect of a finite tip size and applied force on the imaging performance on such materials. Here we exploit the defined scaling of roughness amplitudes on amorphous polymer films to determine the transfer function imposed by the imaging tip. The finite indentation of the nanometer-scale tip into the comparatively soft polymer surface leads to a finite contact area, which in turn effectively acts as a moving average filter for the surface roughness. In the power spectral density (PSD), this leads to an attenuation of the roughness amplitudes related to the Airy pattern known from light diffraction of a circular aperture. This transfer function is affected by the roughness-induced local modulation of the tip height and contact area, which is studied by performing simulations of the polymer roughness and the imaging process. We find that for typical polymer parameters and sharp tips the contact radius of the tip-sample contact can be recovered from the roughness spectrum. We experimentally verify and demonstrate the method by measuring the nanoscale contact radius as a function of applied load and travel distance on a highly cross-linked model polymer. The data are consistent with the Johnson-Kendall-Roberts (JKR) contact model and verifies its applicability at the nanometer scale. Using the model, quantitative values of the elastic sample parameters can be determined.
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Affiliation(s)
- Armin W Knoll
- IBM Research - Zurich, Säumerstrasse 4, 8803 Rüschlikon, Switzerland
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Cheong LL, Paul P, Holzner F, Despont M, Coady DJ, Hedrick JL, Allen R, Knoll AW, Duerig U. Thermal probe maskless lithography for 27.5 nm half-pitch Si technology. Nano Lett 2013; 13:4485-91. [PMID: 23965001 DOI: 10.1021/nl4024066] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Thermal scanning probe lithography is used for creating lithographic patterns with 27.5 nm half-pitch line density in a 50 nm thick high carbon content organic resist on a Si substrate. The as-written patterns in the poly phthaladehyde thermal resist layer have a depth of 8 nm, and they are transformed into high-aspect ratio binary patterns in the high carbon content resist using a SiO2 hard-mask layer with a thickness of merely 4 nm and a sequence of selective reactive ion etching steps. Using this process, a line-edge roughness after transfer of 2.7 nm (3σ) has been achieved. The patterns have also been transferred into 50 nm deep structures in the Si substrate with excellent conformal accuracy. The demonstrated process capabilities in terms of feature density and line-edge roughness are in accordance with today's requirements for maskless lithography, for example for the fabrication of extreme ultraviolet (EUV) masks.
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Affiliation(s)
- Lin Lee Cheong
- IBM Research-Zurich , Säumerstrasse 4, CH-8803 Rüschlikon, Switzerland
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Kaule T, Zhang Y, Emmerling S, Pihan S, Foerch R, Gutmann J, Butt HJ, Berger R, Duerig U, Knoll AW. Nanoscale thermomechanics of wear-resilient polymeric bilayer systems. ACS Nano 2013; 7:748-59. [PMID: 23256440 DOI: 10.1021/nn305047m] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
Abstract
We explore the effect of an ultrathin elastic coating to optimize the mechanical stability of an underlying polymer film for nanoscale applications. The coating consists of a several nanometer thin plasma-polymerized norbornene layer. Scanning probes are used to characterize the system in terms of shear-force-induced wear and thermally assisted indentation. The layer transforms a weakly performing polystyrene film into a highly wear-resistive system, ideal for high-density and low-power data storage applications. The result can be understood from the indentation characteristics with a hot and sharp indenter tip. The latter gives rise to a deformation mode in the fully plastic regime, enabling a simple interpretation of the results. The softening transition and the yield stress of the system on a microsecond time scale and a nanometer size scale were obtained. We show that the plastic deformation is governed by yielding in the polystyrene sublayer, which renders the overall system soft for plastic deformation. The ultrathin protection layer contributes as an elastic skin, which shields part of the temperature and pressure and enables the high wear resistance against lateral forces. Moreover, the method of probing polymers at microsecond and nanometer size scales opens up new opportunities for studying polymer physics in a largely unexplored regime. Thus, we find softening temperatures of more than 100 °C above the polystyrene glass transition, which implies that for the short interaction time scales the glassy state of the polymer is preserved up to this temperature.
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Affiliation(s)
- Tassilo Kaule
- Max Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany
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23
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Abstract
A novel stitching method is presented which does not require special purpose alignment markers and which is particularly adapted to probe lithographic methods, enabling the writing of large patterns exceeding the size limitations imposed by high precision scan stages. The technique exploits the natural roughness of polymeric resist surfaces as a fingerprint marker for the sample position. Theoretical and experimental evidence is provided that sub-nanometer metrological accuracy can be achieved by inspecting the surface roughness in areas with 1 μm linear dimensions. The method has been put to the test in a thermal probe lithography experiment by writing a composite pattern consisting of five 10 μm × 10 μm fields which are seamlessly joined together. The observed stitching error of 10 nm between fields is dominated by inaccuracies of the scanning hardware used in the experiment and is not fundamentally limited by the method per se.
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Affiliation(s)
- Ph Paul
- IBM Research-Zurich, Rüschlikon, Switzerland.
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Holzner F, Kuemin C, Paul P, Hedrick JL, Wolf H, Spencer ND, Duerig U, Knoll AW. Directed placement of gold nanorods using a removable template for guided assembly. Nano Lett 2011; 11:3957-62. [PMID: 21854023 DOI: 10.1021/nl202276q] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
We have used a temperature sensitive polymer film as a removable template to position, and align, gold nanorods onto an underlying target substrate. Shape-matching guiding structures for the assembly of nanorods of size 80 nm × 25 nm have been written by thermal scanning probe lithography. The nanorods were assembled into the guiding structures, which determine both the position and the orientation of single nanorods, by means of capillary interactions. Following particle assembly, the polymer was removed cleanly by thermal decomposition and the nanorods are transferred to the underlying substrate. We have thus demonstrated both the placement and orientation of nanorods with an overall positioning accuracy of ≈10 nm onto an unstructured target substrate.
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Affiliation(s)
- Felix Holzner
- IBM Research-Zurich, Säumerstrasse 4, 8803 Rüschlikon, Switzerland
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25
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Abstract
Scanning probe nanolithography (SPL) has demonstrated its potential in a variety of applications like 3D nanopatterning, 'direct development' lithography, dip-pen deposition or patterning of self-assembled monolayers. One of the main issues holding back SPL has been the limited throughput for patterning and imaging. Here we present a complete lithography and metrology system based on thermomechanical writing into organic resists. Metrology is carried out using a thermoelectric topography sensing method. More specifically, we demonstrate a system with a patterning pixel clock of 500 kHz, 20 mm s(-1) linear scan speed, a positioning accuracy of 10 nm, a read-back frequency bandwidth of 100, 000 line-pairs s(-1) and a turnaround time from patterning to qualifying metrology of 1 min. Thus, we demonstrate a nanolithography system capable of implementing rapid turnaround.
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Affiliation(s)
- Philip C Paul
- IBM Research-Zurich, Säumerstrasse 4, CH-8803 Rüschlikon, Switzerland.
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Knoll AW, Pires D, Coulembier O, Dubois P, Hedrick JL, Frommer J, Duerig U. Probe-based 3-D nanolithography using self-amplified depolymerization polymers. Adv Mater 2010; 22:3361-5. [PMID: 20419710 DOI: 10.1002/adma.200904386] [Citation(s) in RCA: 60] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/19/2023]
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