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Interfacial Interactions during Demolding in Nanoimprint Lithography. MICROMACHINES 2021; 12:mi12040349. [PMID: 33805114 PMCID: PMC8064091 DOI: 10.3390/mi12040349] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/09/2021] [Revised: 03/02/2021] [Accepted: 03/10/2021] [Indexed: 11/17/2022]
Abstract
Nanoimprint lithography (NIL) is a useful technique for the fabrication of nano/micro-structured materials. This article reviews NIL in the field of demolding processes and is divided into four parts. The first part introduces the NIL technologies for pattern replication with polymer resists (e.g., thermal and UV-NIL). The second part reviews the process simulation during resist filling and demolding. The third and fourth parts discuss in detail the difficulties in demolding, particularly interfacial forces between mold (template) and resist, during NIL which limit its capability for practical commercial applications. The origins of large demolding forces (adhesion and friction forces), such as differences in the thermal expansion coefficients (CTEs) between the template and the imprinted resist, or volumetric shrinkage of the UV-curable polymer during curing, are also illustrated accordingly. The plausible solutions for easing interfacial interactions and optimizing demolding procedures, including exploring new resist materials, employing imprint mold surface modifications (e.g., ALD-assisted conformal layer covering imprint mold), and finetuning NIL process conditions, are presented. These approaches effectively reduce the interfacial demolding forces and thus lead to a lower defect rate of pattern transfer. The objective of this review is to provide insights to alleviate difficulties in demolding and to meet the stringent requirements regarding defect control for industrial manufacturing while at the same time maximizing the throughput of the nanoimprint technique.
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Nakagawa M, Kaneko S, Ito S. Demolding in Ultraviolet Nanoimprinting Assisted by a Nanoscale Lubricating Fluid Layer of Condensed Alternative Chlorofluorocarbon. BULLETIN OF THE CHEMICAL SOCIETY OF JAPAN 2016. [DOI: 10.1246/bcsj.20160107] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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Vitale A, Bongiovanni R, Ameduri B. Fluorinated Oligomers and Polymers in Photopolymerization. Chem Rev 2015; 115:8835-66. [DOI: 10.1021/acs.chemrev.5b00120] [Citation(s) in RCA: 166] [Impact Index Per Article: 18.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Affiliation(s)
- Alessandra Vitale
- Department
of Chemical Engineering, Imperial College London, South Kensington
Campus, London SW7 2AZ, United Kingdom
| | - Roberta Bongiovanni
- Department
of Applied Science and Technology, Politecnico di Torino, C.so Duca
degli Abruzzi 24, 10129 Torino, Italy
| | - Bruno Ameduri
- Engineering
and Macromolecular Architectures, Institut Charles Gerhardt UMR (CNRS) 5253, Ecole Nationale Supérieure de Chimie de Montpellier, 8 Rue Ecole Normale, 34296 Montpellier Cedex 5, France
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Nakagawa M, Kobayashi K, Hattori AN, Ito S, Hiroshiba N, Kubo S, Tanaka H. Selection of di(meth)acrylate monomers for low pollution of fluorinated mold surfaces in ultraviolet nanoimprint lithography. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2015; 31:4188-4195. [PMID: 25793911 DOI: 10.1021/acs.langmuir.5b00325] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
We used fluorescence microscopy to show that low adsorption of resin components by a mold surface was necessary for continuous ultraviolet (UV) nanoimprinting, as well as generation of a low release energy on detachment of a cured resin from a template mold. This is because with low mold pollution, fracture on demolding occurred at the interface between the mold and cured resin surfaces rather than at the outermost part of the cured resin. To achieve low mold pollution, we investigated the radical photopolymerization behaviors of fluorescent UV-curable resins and the mechanical properties (fracture toughness, surface hardness, and release energy) of the cured resin films for six types of di(meth)acrylate-based monomers with similar chemical structures, in which polar hydroxy and aromatic bulky bisphenol moieties and methacryloyl or acryloyl reactive groups were present or absent. As a result, we selected bisphenol A glycerolate dimethacrylate (BPAGDM), which contains hydroxy, bisphenol, and methacryloyl moieties, which give good mechanical properties, monomer bulkiness, and mild reactivity, respectively, as a suitable base monomer for UV nanoimprinting under an easily condensable alternative chlorofluorocarbon (HFC-245fa) atmosphere. The fluorescent UV-curable BPAGDM resin was used for UV nanoimprinting and lithographic reactive ion etching of a silicon surface with 32 nm line-and-space patterns without a hard metal layer.
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Affiliation(s)
- Masaru Nakagawa
- †Polymer • Hybrid Materials Research Center, Institute of Multidisciplinary Research for Advanced Materials (IMRAM), Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai 980-8577, Japan
- ‡Japan Science and Technology Agency (JST), Core Research Evolutional Science and Technology (CREST), 7 Gobancho, Chiyoda, Tokyo 102-0076, Japan
| | - Kei Kobayashi
- †Polymer • Hybrid Materials Research Center, Institute of Multidisciplinary Research for Advanced Materials (IMRAM), Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai 980-8577, Japan
| | - Azusa N Hattori
- §Institute of Scientific and Industrial Research (ISIR), Osaka University, 8-1 Mihogaoka, Ibaraki, Osaka 567-0047, Japan
| | - Shunya Ito
- †Polymer • Hybrid Materials Research Center, Institute of Multidisciplinary Research for Advanced Materials (IMRAM), Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai 980-8577, Japan
| | - Nobuya Hiroshiba
- †Polymer • Hybrid Materials Research Center, Institute of Multidisciplinary Research for Advanced Materials (IMRAM), Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai 980-8577, Japan
| | - Shoichi Kubo
- †Polymer • Hybrid Materials Research Center, Institute of Multidisciplinary Research for Advanced Materials (IMRAM), Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai 980-8577, Japan
| | - Hidekazu Tanaka
- §Institute of Scientific and Industrial Research (ISIR), Osaka University, 8-1 Mihogaoka, Ibaraki, Osaka 567-0047, Japan
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Ito S, Kaneko S, Yun CM, Kobayashi K, Nakagawa M. Investigation of fluorinated (Meth)acrylate monomers and macromonomers suitable for a hydroxy-containing acrylate monomer in UV nanoimprinting. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2014; 30:7127-7133. [PMID: 24892792 DOI: 10.1021/la501629n] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
We investigated reactive fluorinated (meth)acrylate monomers and macromonomers that caused segregation at the cured resin surface of a viscous hydroxy-containing monomer, glycerol 1,3-diglycerolate diacrylate (GDD), and decreased the demolding energy in ultraviolet (UV) nanoimprinting with spin-coated films under a condensable alternative chlorofluorocarbon gas atmosphere. The X-ray photoelectron spectroscopy and contact angle measurements used to determine the surface free energy suggested that a nonvolatile silicone-based methacrylate macromonomer with fluorinated alkyl groups segregated at the GDD-based cured resin surface and decreased the surface free energy, while fluorinated acrylate monomers hardly decreased the surface free energy because of their evaporation during the annealing of the spin-coated films. The average demolding energy of GDD-based cured resins with the macromonomer having fluorinated alkyl groups was smaller than that with the macromonomer having hydrocarbon alkyl groups. The fluorinated alkyl groups were responsible for decreasing the demolding energy rather than the polysiloxane main chains. We demonstrated that the GDD-based UV-curable resin with the fluorinated silicone-based macromonomer was suitable for step-and-repeat UV nanoimprinting with a bare silica mold, in addition to silica molds treated by chemical vapor surface modification with trifluoro-1,1,2,2-tetrahydropropyltrimethoxysilane (FAS3) and tridecafluoro-1,1,2,2-tetrahydrooctyltrimethoxysilane (FAS13).
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Affiliation(s)
- Shunya Ito
- Institute of Multidisciplinary Research for Advanced Materials, Tohoku University , 2-1-1 Katahira, Aoba-ku, Sendai 980-8577, Japan
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Matsui S, Hiroshima H, Hirai Y, Nakagawa M. Breakthrough Achievement In Nanoimprint Lithography Using PFP Condensable Gas. J PHOTOPOLYM SCI TEC 2014. [DOI: 10.2494/photopolymer.27.61] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Nakamura N, Yamashita T, Kitagawa T, Kawata H, Shirai M, Hirai Y. Evaluation of Template Release Energy with Use of Fluorinated Segregation Agents for UV Nanoimprint Resists. J PHOTOPOLYM SCI TEC 2014. [DOI: 10.2494/photopolymer.27.111] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Oyama T, Okada M, Iyoshi S, Haruyama Y, Yamashita T, Matsui S. Effect of Fluorosurfactant contained in Resin for Anti-sticking Layer Free UV Nanoimprinting. J PHOTOPOLYM SCI TEC 2014. [DOI: 10.2494/photopolymer.27.117] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Lin H, Gan Y, Jiang X, Yin J. Thiol-yne Photo-curable Hybrid Resist: An Alternative for UV Nanoimprint Lithography (UV-NIL). J PHOTOPOLYM SCI TEC 2014. [DOI: 10.2494/photopolymer.27.121] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Hong Lin
- HCC-SJTU R&D Center, School of Chemistry and Chemical Technology, Shanghai Jiao Tong University
| | - Yanchang Gan
- HCC-SJTU R&D Center, School of Chemistry and Chemical Technology, Shanghai Jiao Tong University
| | - Xuesong Jiang
- HCC-SJTU R&D Center, School of Chemistry and Chemical Technology, Shanghai Jiao Tong University
| | - Jie Yin
- HCC-SJTU R&D Center, School of Chemistry and Chemical Technology, Shanghai Jiao Tong University
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Oyama T, Okada M, Iyoshi S, Haruyama Y, Miyake H, Mizuta T, Matsu S. Surface Evaluation of Cationic UV-curable Resin with Fluorine Additive by X-ray Photoelectron Spectroscopy. J PHOTOPOLYM SCI TEC 2013. [DOI: 10.2494/photopolymer.26.129] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Kim BG, Jeong EJ, Kwon KH, Yoo YE, Choi DS, Kim J. Controlling mold releasing propensity--the role of surface energy and a multiple chain transfer agent. ACS APPLIED MATERIALS & INTERFACES 2012; 4:3465-3470. [PMID: 22757660 DOI: 10.1021/am3005303] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
As the desired feature size of mold-assisted lithography decreases rapidly efficient demolding process becomes more challenging due to strong adhesion between polymeric resists and fine-featured molds. We synthesized new macromolecular additives and investigated the effects of surface energy and contraction of resist materials on demolding propensity by monitoring the adhesion force between the resist and the applied mold. The resist's surface energy was controlled, as inferred from water contact angle measurements, by chemically modifying its hydroxyl functionality. The resist's degree of volume shrinkage during the photocuring procedure was also controlled by mixing in a newly developed chemical that has a multiple radical chain transfer capability. The adhesion force was proportionally reduced as the surface energy of the resist materials decreased and as the volume shrinkage was reduced. When the volume shrinkage control was applied in conjunction with the low surface energy resist material (LS-30UV), we obtained an optimized condition requiring a minimum force for releasing the mold from the cured resist layer.
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Affiliation(s)
- Bong-Gi Kim
- Macromolecular Science and Engineering, ‡Department of Materials Science and Engineering, and ⊥Chemical Engineering, University of Michigan , Ann Arbor, Michigan 48109, United States
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Lin H, Wan X, Jiang X, Wang Q, Yin J. A “thiol-ene” photo-curable hybrid fluorinated resist for the high-performance replica mold of nanoimprint lithography (NIL). ACTA ACUST UNITED AC 2012. [DOI: 10.1039/c1jm13765d] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Alvine KJ, Ding Y, Douglas JF, Wook Ro H, Okerberg BC, Karim A, Lavery KA, Lin-Gibson S, Soles CL. Effect of fluorosurfactant on capillary instabilities in nanoimprinted polymer patterns. ACTA ACUST UNITED AC 2009. [DOI: 10.1002/polb.21884] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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Double-anchoring fluorinated molecules for antiadhesion mold treatment in UV nanoimprint lithography. ACTA ACUST UNITED AC 2009. [DOI: 10.1116/1.3245993] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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Schvartzman M, Mathur A, Hone J, Jahnes C, Wind SJ. Plasma fluorination of carbon-based materials for imprint and molding lithographic applications. APPLIED PHYSICS LETTERS 2008; 93:153105. [PMID: 19529791 PMCID: PMC2684694 DOI: 10.1063/1.2944997] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/18/2008] [Accepted: 05/06/2008] [Indexed: 05/27/2023]
Abstract
Diamondlike carbon nanoimprint templates are modified by exposure to a fluorocarbon-based plasma, yielding an ultrathin layer of a fluorocarbon material on the surface which has a very low surface energy with excellent antiwear properties. We demonstrate the use of these plasma fluorinated templates to pattern features with dimensions approximately 20 nm and below. Furthermore, we show that this process is extendable to other carbon-based materials. Plasma fluorination can be applied directly to nanoimprint resists as well as to molds used to form elastomer stamps for microcontact printing and other applications requiring easy mold release.
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Houle FA, Miller DC, Fornof A, Trung H, Raoux S, Sooriyakumaran R, Ito H, Hart M. Nanoimprint Materials Systems. J PHOTOPOLYM SCI TEC 2008. [DOI: 10.2494/photopolymer.21.563] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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