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Kiruthika S, Radha B. Direct Micromolding of Bimetals and Transparent Conducting Oxide Using Metal-TOABr Complexes as Single-Source Precursors. ACS OMEGA 2020; 5:20739-20745. [PMID: 32875207 PMCID: PMC7450499 DOI: 10.1021/acsomega.0c00407] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/29/2020] [Accepted: 04/29/2020] [Indexed: 06/11/2023]
Abstract
Patterning of metals, alloys, and conducting oxides is vitally important for many industrial applications pertaining to many technological devices. In this report, we have used the metal anion alkyl ammonium complex (M-TOABr) as a single-source precursor to obtain thin films as well as micro (μ)-patterns of bimetals (Au-Pd, Au-Pt, Au-Cu, and Pt-Pd) and conducting oxides (ITO). This complex can be easily filled inside the soft mold and converted to the desired material in a single step known as direct patterning. The as-obtained μ-pattern comprises a well-connected network of nanocrystals giving rise to metallic conductivity. These periodically aligned bimetals and transparent conducting oxide (TCO) microwires could effectively serve as electrodes as well as an electrocatalyst with the prudence of providing passage for light transmission for many functional photoelectrochemical devices. In addition, the electrochemical stability of the bimetallic film was examined by fabricating a supercapacitor device and by studying its performance.
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Affiliation(s)
- S. Kiruthika
- School of Electrical & Electronics Engineering (SEEE), SASTRA Deemed University, Thanjavur 613 401, Tamil Nadu, India
| | - B. Radha
- Department of Physics
& Astronomy, School of Natural Sciences, University of Manchester, Manchester M13 9PL, U.K.
- National
Graphene Institute, University of Manchester, Manchester M13 9PL, U.K.
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2
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Jin B, Shao C, Wang Y, Mu Z, Liu Z, Tang R. Anisotropic Epitaxial Behavior in the Amorphous Phase-Mediated Hydroxyapatite Crystallization Process: A New Understanding of Orientation Control. J Phys Chem Lett 2019; 10:7611-7616. [PMID: 31749366 DOI: 10.1021/acs.jpclett.9b03109] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
The precise control of crystallization is a key in the construction and engineering of crystalline materials, especially in biomineralization. Although it is generally accepted that biomineral crystals have evolved from their amorphous precursors, there are intense debates about crystallographic orientation control. By using in situ high-resolution transmission electron microscopy, we herein reveal that hydroxyapatite (HAP) is produced through its epitaxial growth from amorphous calcium phosphate with a preferential c-axis orientation. Abnormally but interestingly, this anisotropic epitaxial crystallization priority along the c-axis is not affected by the existing HAP crystalline substrate, which is exactly the same on either {002} or {100} facets. Molecular dynamics simulations suggest this preference is correlated with the interfacial energetic controls at the amorphous-crystalline transition frontier. The orientation control of biominerals here shows the key role of the interface energy, rather that the organic molecules or matrices, which provides a complementary understanding of the general c-axis orientation control of HAP in various biomineralization cases and aids in the development of an alternative strategy for crystallization control of functional materials.
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Affiliation(s)
| | | | - Yanming Wang
- Department of Materials Science and Engineering , Massachusetts Institute of Technology , 77 Massachusetts Avenue , Cambridge , Massachusetts 02139 , United States
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3
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Bi K, Xiang Q, Chen Y, Shi H, Li Z, Lin J, Zhang Y, Wan Q, Zhang G, Qin S, Zhang X, Duan H. Direct patterning of highly-conductive graphene@copper composites using copper naphthenate as a resist for graphene device applications. NANOSCALE 2017; 9:16755-16763. [PMID: 29072744 DOI: 10.1039/c7nr05779b] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
We report an electron-beam lithography process to directly fabricate graphene@copper composite patterns without involving metal deposition, lift-off and etching processes using copper naphthenate as a high-resolution negative-tone resist. As a commonly used industrial painting product, copper naphthenate is extremely cheap with a long shelf time but demonstrates an unexpected patterning resolution better than 10 nm. With appropriate annealing under a hydrogen atmosphere, the produced graphene@copper composite patterns show high conductivity of ∼400 S cm-1. X-ray diffraction, conformal Raman spectroscopy and X-ray photoelectron spectroscopy were used to analyze the chemical composition of the final patterns. With the properties of high resolution and high conductivity, the patterned graphene@copper composites could be used as conductive pads and interconnects for graphene electronic devices with ohmic contacts. Compared to common fabrication processes involving metal evaporation and lift-off steps, this pattern-transfer-free fabrication process using copper naphthenate resist is direct and simple but allows comparable device performance in practical device applications.
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Affiliation(s)
- Kaixi Bi
- School of Physics and Electronics, State Key Laboratory of Advanced Design and Manufacturing for Vehicle Body, Hunan University, Changsha 410082, China.
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Saifullah MSM, Ganesan R, Lim SH, Hussain H, Low HY. Large area sub-100 nm direct nanoimprinting of palladium nanostructures. RSC Adv 2016. [DOI: 10.1039/c6ra00234j] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
We demonstrate a simple direct nanoimprinting method for fabricating palladium nanostructures that involves in situ free radical polymerization of a resin consisting of an acrylate-based crosslinker and a palladium metal precursor.
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Affiliation(s)
- Mohammad S. M. Saifullah
- Institute of Materials Research and Engineering
- A*STAR (Agency for Science, Technology and Research)
- Singapore 138634
- Republic of Singapore
| | - Ramakrishnan Ganesan
- Department of Chemistry
- Birla Institute of Technology & Science
- Hyderabad-500 078
- India
| | - Su Hui Lim
- Institute of Materials Research and Engineering
- A*STAR (Agency for Science, Technology and Research)
- Singapore 138634
- Republic of Singapore
- Department of Electrical and Computer Engineering
| | - Hazrat Hussain
- Department of Chemistry
- Quaid-i-Azam University
- Islamabad 45320
- Pakistan
| | - Hong Yee Low
- Engineering Product Development
- Singapore University of Technology & Design
- Singapore 487372
- Republic of Singapore
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Rowthu S, Böhlen K, Bowen P, Hoffmann P. Surface 3D Micro Free Forms: Multifunctional Microstructured Mesoporous α-Alumina by in Situ Slip Casting Using Excimer Laser Ablated Polycarbonate Molds. ACS APPLIED MATERIALS & INTERFACES 2015; 7:24458-24469. [PMID: 26478952 DOI: 10.1021/acsami.5b04748] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Ceramic surface microstructuring is a rapidly growing field with a variety of applications in tribology, wetting, biology, and so on. However, there are limitations to large-area microstructuring and fabrication of three-dimensional (3D) micro free forms. Here, we present a route to obtain intricate surface structures through in situ slip casting using polydimethylsiloxane (PDMS) negative molds which are replicated from excimer laser ablated polycarbonate (PC) master molds. PC sheets are ablated with a nanosecond KrF (λ = 248 nm) excimer laser mask projection system to obtain micron-scale 3D surface features over a large area of up to 3 m(2). Complex surface structures that include 3D free forms such as 3D topography of Switzerland, shallow structures such as diffractive optical elements (60 nm step) and conical micropillars have been obtained. The samples are defect-free produced with thicknesses of up to 10 mm and 120 mm diameter. The drying process of the slip cast alumina slurry takes place as a one-dimensional process, through surface evaporation and water permeation through the PDMS membrane. This allows homogeneous one-dimensional shrinkage during the drying process, independent of the sample's lateral dimensions. A linear mass diffusion model has been proposed to predict and explain the drying process of these ceramic colloidal suspensions. The calculated drying time is linearly proportional to the height of the slurry and the thickness of the negatively structured PDMS and is validated by the experimental results. An experimentally observed optimum Sylgard PDMS thickness range of ∼400 μm to 1 mm has achieved the best quality microstructured green compacts. Further, the model predicts that the drying time is independent of the microstructured areas and was validated using experimental observations carried out with microstructured areas of 300 mm(2), 1200 mm(2), and 120 cm(2). Therefore, in principle, the structures can be further replicated in areas up to 3 m(2) with the same drying time for the same slurry height. The surface-structured ceramics display interesting wetting properties, for example, eicosane-coated mesoporous microstructured alumina shows superhydrophobic behavior. Additionally, ceramic bulk samples could be further used as second-generation very hard and low-wear molds for further microfabrication.
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Affiliation(s)
- Sriharitha Rowthu
- Advanced Materials Processing Laboratory, Empa, Swiss Federal Laboratories for Materials Science and Technology , Feuerwerkerstrasse 39, CH-3602 Thun, Switzerland
| | - Karl Böhlen
- Advanced Materials Processing Laboratory, Empa, Swiss Federal Laboratories for Materials Science and Technology , Feuerwerkerstrasse 39, CH-3602 Thun, Switzerland
| | - Paul Bowen
- Powder Technology Laboratory, Materials Science and Engineering, Ecole Polytechnique Fédérale de Lausanne (EPFL) , Station 12, CH-1015 Lausanne, Switzerland
| | - Patrik Hoffmann
- Advanced Materials Processing Laboratory, Empa, Swiss Federal Laboratories for Materials Science and Technology , Feuerwerkerstrasse 39, CH-3602 Thun, Switzerland
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Kurra N, Kiruthika S, Kulkarni GU. Solution processed sun baked electrode material for flexible supercapacitors. RSC Adv 2014. [DOI: 10.1039/c4ra02934h] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Pd hexadecylthiolate decomposes under sunlight leading to a conducting nanocrystalline Pd–carbon composite. Thus formed films serve as supercapacitor electrodes. The organic precursor enables the fabrication of micro-supercapacitors using e-beam lithography.
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Affiliation(s)
- Narendra Kurra
- Chemistry & Physics of Materials Unit and Thematic Unit of Excellence on Nanochemistry
- Jawaharlal Nehru Centre for Advanced Scientific Research
- Bangalore 560 064, India
| | - S. Kiruthika
- Chemistry & Physics of Materials Unit and Thematic Unit of Excellence on Nanochemistry
- Jawaharlal Nehru Centre for Advanced Scientific Research
- Bangalore 560 064, India
| | - Giridhar U. Kulkarni
- Chemistry & Physics of Materials Unit and Thematic Unit of Excellence on Nanochemistry
- Jawaharlal Nehru Centre for Advanced Scientific Research
- Bangalore 560 064, India
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Radha B, Liu G, Eichelsdoerfer DJ, Kulkarni GU, Mirkin CA. Layer-by-layer assembly of a metallomesogen by dip-pen nanolithography. ACS NANO 2013; 7:2602-2609. [PMID: 23402390 DOI: 10.1021/nn306013e] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Palladium alkanethiolates are introduced here as a novel liquid ink for dip-pen nanolithography (DPN). These structures exhibit the unusual characteristic of layer-by-layer assembly, allowing one to deposit a desired number of metal ions on a surface, which can subsequently be reduced via thermolysis to form active catalytic structures. Such structures have been used to generate contiguous metallic or conducting polymer nanoscale architectures by electroless deposition.
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Affiliation(s)
- Boya Radha
- Department of Materials Science and Engineering, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208, United States
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8
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Radha B, Lim SH, Saifullah MSM, Kulkarni GU. Metal hierarchical patterning by direct nanoimprint lithography. Sci Rep 2013; 3:1078. [PMID: 23446801 PMCID: PMC3584315 DOI: 10.1038/srep01078] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2012] [Accepted: 11/29/2012] [Indexed: 11/09/2022] Open
Abstract
Three-dimensional hierarchical patterning of metals is of paramount importance in diverse fields involving photonics, controlling surface wettability and wearable electronics. Conventionally, this type of structuring is tedious and usually involves layer-by-layer lithographic patterning. Here, we describe a simple process of direct nanoimprint lithography using palladium benzylthiolate, a versatile metal-organic ink, which not only leads to the formation of hierarchical patterns but also is amenable to layer-by-layer stacking of the metal over large areas. The key to achieving such multi-faceted patterning is hysteretic melting of ink, enabling its shaping. It undergoes transformation to metallic palladium under gentle thermal conditions without affecting the integrity of the hierarchical patterns on micro- as well as nanoscale. A metallic rice leaf structure showing anisotropic wetting behavior and woodpile-like structures were thus fabricated. Furthermore, this method is extendable for transferring imprinted structures to a flexible substrate to make them robust enough to sustain numerous bending cycles.
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Affiliation(s)
- Boya Radha
- Chemistry and Physics of Materials Unit and DST Unit on Nanoscience, Jawaharlal Nehru Centre for Advanced Scientific Research, Jakkur P.O., Bangalore 560 064, India
- Institute of Materials Research and Engineering, A*STAR (Agency for Science, Technology and Research), 3 Research Link, Singapore 117602, Republic of Singapore
| | - Su Hui Lim
- Institute of Materials Research and Engineering, A*STAR (Agency for Science, Technology and Research), 3 Research Link, Singapore 117602, Republic of Singapore
- Department of Electrical and Computer Engineering, National University of Singapore, 4 Engineering Drive 3, Singapore 117576, Republic of Singapore
| | - Mohammad S. M. Saifullah
- Institute of Materials Research and Engineering, A*STAR (Agency for Science, Technology and Research), 3 Research Link, Singapore 117602, Republic of Singapore
| | - Giridhar U. Kulkarni
- Chemistry and Physics of Materials Unit and DST Unit on Nanoscience, Jawaharlal Nehru Centre for Advanced Scientific Research, Jakkur P.O., Bangalore 560 064, India
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9
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Shi S, Lu N, Lu Y, Wang Y, Qi D, Xu H, Chi L. Fabrication of periodic metal nanowires with microscale mold by nanoimprint lithography. ACS APPLIED MATERIALS & INTERFACES 2011; 3:4174-4179. [PMID: 21978230 DOI: 10.1021/am2010338] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
In this paper, a simple method is demonstrated for fabricating periodic metal nanowires based on the unconventional nanoimprint lithography (NIL) technique. Using this method, sub-100 nm metal nanowires with the rectangular cross-section are fabricated with microscale stamp. Furthermore, the metal nanowires with different widths and heights can be generated by adjusting the imprinting parameters with the same stamp. The metal nanowires prepared with this method can be used for chemical sensing, such as ammonia sensing, and it may have applications in optical signal processing.
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Radha B, Kiruthika S, Kulkarni GU. Metal Anion–Alkyl Ammonium Complexes as Direct Write Precursors to Produce Nanopatterns of Metals, Nitrides, Oxides, Sulfides, And Alloys. J Am Chem Soc 2011; 133:12706-13. [DOI: 10.1021/ja2039612] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- B. Radha
- Chemistry and Physics of Materials Unit and DST Unit on Nanoscience, Jawaharlal Nehru Centre for Advanced Scientific Research, Jakkur P.O., Bangalore 560064, India
| | - S. Kiruthika
- Chemistry and Physics of Materials Unit and DST Unit on Nanoscience, Jawaharlal Nehru Centre for Advanced Scientific Research, Jakkur P.O., Bangalore 560064, India
| | - G. U. Kulkarni
- Chemistry and Physics of Materials Unit and DST Unit on Nanoscience, Jawaharlal Nehru Centre for Advanced Scientific Research, Jakkur P.O., Bangalore 560064, India
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11
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Radha B, Sagade AA, Kulkarni GU. Flexible and semitransparent strain sensors based on micromolded Pd nanoparticle-carbon μ-stripes. ACS APPLIED MATERIALS & INTERFACES 2011; 3:2173-8. [PMID: 21678984 DOI: 10.1021/am2002873] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
Flexible resistive strain sensors have been fabricated by micromolding Pd alkanethiolate on polyimide substrates and subjecting to thermolysis in air. Thus produced stripes were ∼1 μm wide with spacing of ∼0.5 μm and contained Pd nanoparticles in carbon matrix. The nanoparticle size and the nature of carbon are much dependent on the thermolysis temperature as is also the resistance of the microstripes. Generally, lower thermolysis temperatures (<230 °C) produced stripes containing small Pd nanoparticles with significant fraction of carbon from the precursor decomposition. The stripes were poorly conducting yet interestingly, exhibited change of resistance under tensile and compressive strain. Particularly noteworthy are the stripes produced from 195 °C thermolysis, which showed a high gauge factor of ∼390 with strain sensitivity, 0.09%. With molding at 230 °C, the stripes obtained were highly conducting, and amazingly did not change the resistance with strain even after several bending cycles. The latter are ideal as flexible conduits and interconnects. Thus, the article reports a method of producing flexible sensitive strain sensors on one hand and on the other, flexible conduits with unchanging resistance, merely by fine-tuning the precursor decomposition under the molding conditions.
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Affiliation(s)
- B Radha
- Chemistry and Physics of Materials Unit and DST Unit on Nanoscience, Jawaharlal Nehru Centre for Advanced Scientific Research, Jakkur P.O., Bangalore 560064, India
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12
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Abstract
Metal nanowire patterning in the form of grating structures has been carried out using a wide range of lithography techniques, and many hybrid methods derived from them. The challenge is to achieve sub-100 nm linewidths with controllable spacing and thickness over large areas of substrates with high throughput. In particular, the patterns with linewidth and spacing of a few tens of nm offer properties of great interest in optoelectronics and plasmonics. Crossbar grating structures--two gratings patterned perpendicular to each other--will play an important role as ultra-high density electrode grids in memristive devices for non-volatile memory.
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Affiliation(s)
- G U Kulkarni
- Chemistry and Physics of Materials Unit and DST Unit on Nanoscience,Jawaharlal Nehru Centre for Advanced Scientific Research, Jakkur PO, Bangalore 560064, India.
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13
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Heun S, Radha B, Ercolani D, Kulkarni GU, Rossi F, Grillo V, Salviati G, Beltram F, Sorba L. Coexistence of vapor-liquid-solid and vapor-solid-solid growth modes in Pd-assisted InAs nanowires. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2010; 6:1935-1941. [PMID: 20662001 DOI: 10.1002/smll.201000811] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
During the growth of InAs nanowires from Pd catalyst particles on InAs(111)A substrates, two distinct classes of nanowires are observed with smooth or zigzagged sidewalls. It is shown that this is related to a bimodal distribution of the wire-tip diameter: above a critical diameter wires grow with smooth sidewalls, and below with zigzagged morphology. Transmission electron microscopy analysis shows that the catalyst particles at the tip of zigzagged wires are smooth and have a higher aspect ratio than those at the tip of smooth wires. Zigzagged wires grow from liquid particles in the vapor-liquid-solid (VLS) mode whereas the smooth ones grow from solid particles in the vapor-solid-solid (VSS) mode.
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Affiliation(s)
- Stefan Heun
- NEST, Istituto Nanoscienze-CNR and Scuola Normale Superiore, Piazza S Silvestro 12, 56127 Pisa, Italy.
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Scott A, Gupta R, Kulkarni GU. A Simple Water-Based Synthesis of Au Nanoparticle/PDMS Composites for Water Purification and Targeted Drug Release. MACROMOL CHEM PHYS 2010. [DOI: 10.1002/macp.201000079] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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Arora A, Simone G, Salieb-Beugelaar GB, Kim JT, Manz A. Latest Developments in Micro Total Analysis Systems. Anal Chem 2010; 82:4830-47. [PMID: 20462185 DOI: 10.1021/ac100969k] [Citation(s) in RCA: 372] [Impact Index Per Article: 26.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Affiliation(s)
- Arun Arora
- KIST Europe, Korea Institute of Science and Technology, Campus E71, 66123 Saarbrücken, Germany, FRIAS, Freiburg Institute for Advanced Studies, Albert-Ludwigs-Universität Freiburg, Albertstrasse 19, 79104 Freiburg, Germany, IMTEK, Institute for Microsystem Technology, University of Freiburg, Georges-Köhler-Allee 103, 79110 Freiburg, Germany, and MESA+ Institute for Nanotechnology/Lab-on-a-Chip Group, Twente University, Building Carré, 7500 AE, Enschede, The Netherlands
| | - Giuseppina Simone
- KIST Europe, Korea Institute of Science and Technology, Campus E71, 66123 Saarbrücken, Germany, FRIAS, Freiburg Institute for Advanced Studies, Albert-Ludwigs-Universität Freiburg, Albertstrasse 19, 79104 Freiburg, Germany, IMTEK, Institute for Microsystem Technology, University of Freiburg, Georges-Köhler-Allee 103, 79110 Freiburg, Germany, and MESA+ Institute for Nanotechnology/Lab-on-a-Chip Group, Twente University, Building Carré, 7500 AE, Enschede, The Netherlands
| | - Georgette B. Salieb-Beugelaar
- KIST Europe, Korea Institute of Science and Technology, Campus E71, 66123 Saarbrücken, Germany, FRIAS, Freiburg Institute for Advanced Studies, Albert-Ludwigs-Universität Freiburg, Albertstrasse 19, 79104 Freiburg, Germany, IMTEK, Institute for Microsystem Technology, University of Freiburg, Georges-Köhler-Allee 103, 79110 Freiburg, Germany, and MESA+ Institute for Nanotechnology/Lab-on-a-Chip Group, Twente University, Building Carré, 7500 AE, Enschede, The Netherlands
| | - Jung Tae Kim
- KIST Europe, Korea Institute of Science and Technology, Campus E71, 66123 Saarbrücken, Germany, FRIAS, Freiburg Institute for Advanced Studies, Albert-Ludwigs-Universität Freiburg, Albertstrasse 19, 79104 Freiburg, Germany, IMTEK, Institute for Microsystem Technology, University of Freiburg, Georges-Köhler-Allee 103, 79110 Freiburg, Germany, and MESA+ Institute for Nanotechnology/Lab-on-a-Chip Group, Twente University, Building Carré, 7500 AE, Enschede, The Netherlands
| | - Andreas Manz
- KIST Europe, Korea Institute of Science and Technology, Campus E71, 66123 Saarbrücken, Germany, FRIAS, Freiburg Institute for Advanced Studies, Albert-Ludwigs-Universität Freiburg, Albertstrasse 19, 79104 Freiburg, Germany, IMTEK, Institute for Microsystem Technology, University of Freiburg, Georges-Köhler-Allee 103, 79110 Freiburg, Germany, and MESA+ Institute for Nanotechnology/Lab-on-a-Chip Group, Twente University, Building Carré, 7500 AE, Enschede, The Netherlands
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Yoon H, Kee Choi M, Suh KY, Char K. Self-modulating polymer resist patterns in pressure-assisted capillary force lithography. J Colloid Interface Sci 2010; 346:476-82. [PMID: 20362997 DOI: 10.1016/j.jcis.2010.03.023] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2010] [Revised: 03/07/2010] [Accepted: 03/10/2010] [Indexed: 11/30/2022]
Abstract
We present pressure-assisted capillary force lithography (CFL) to generate self-modulating polymer resist patterns without residual layers and film instability. The method utilizes roof collapse of a patterned, deformable poly(dimethyl siloxane) (PDMS) mold that is placed on a thermoplastic polymer film with a constant external pressure (approximately 4 bars) and the resulting shape-variable capillary filling of a polymer melt into the reduced void space. A constraint on the coated polymer layer thickness was derived in order to ensure that there is no residual layer left after patterning and at the same time that film stability is guaranteed without film dewetting within the cavity. In addition, the height of a polymer pattern at the center of the filled void was estimated as a function of initial polymer layer thickness based on the assumption of the hemispherical shape of a meniscus and full capillary rise, which agrees well with the experimental data.
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Affiliation(s)
- Hyunsik Yoon
- School of Chemical and Biological Engineering, The WCU Program of Chemical Convergence for Energy and Environment, Seoul National University, Seoul 151-744, Republic of Korea
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