Liquid transfer imprint lithography: A new route to residual layer thickness control

Koo, Namil; Kim, Jung Wuk; Otto, Martin; Moormann, Christian; Kurz, H.

doi:10.1116/1.3660792

Cited by 27 publications

(20 citation statements)

References 5 publications

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“…In the future, particularly in view of upscaling replication to large scale roll-to-roll processes, a combination of MIMIC and NIL could help to achieve low residual layer imprinting of thermoplastic and UVcurable materials. For this, resist transfer methods such as liquid transfer imprint lithography (LTIL) could be advantageous 56,57 .…”

Section: Discussionmentioning

confidence: 99%

High-aspect-ratio nanoimprint process chains

et al. 2017

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Different methods capable of developing complex structures and building elements with high-aspect-ratio nanostructures combined with microstructures, which are of interest in nanophotonics, are presented. As originals for subsequent replication steps, two families of masters were developed: (i) 3.2 μm deep, 180 nm wide trenches were fabricated by silicon cryo-etching and (ii) 9.8 μm high, 350 nm wide ridges were fabricated using 2-photon polymerization direct laser writing. Both emerging technologies enable the vertical smooth sidewalls needed for a successful imprint into thin layers of polymers with aspect ratios exceeding 15. Nanoridges with high aspect ratios of up to 28 and no residual layer were produced in Ormocers using the micromoulding into capillaries (MIMIC) process with subsequent ultraviolet-curing. This work presents and balances the different fabrication routes and the subsequent generation of working tools from masters with inverted tones and the combination of hard and soft materials. This provides these techniques with a proof of concept for their compatibility with high volume manufacturing of complex micro-and nanostructures.Keywords: cryo-etching; direct 6 write laser lithography; high aspect ratio; moulding; nanoimprint lithography; Ormocer; photonic nanofences; 2-photon polymerization INTRODUCTION High-aspect-ratio microstructures (HARMS), that is, structures with a large height/width ratio, have found many applications 1,2 such as X-ray gratings 3 , gas chromatography columns 4 , magnetic coils 5 , X-ray telescopes 6 , micro-gears 7 , micro-capacitors with highaspect-ratio (HAR) cantilevers 8 , and micromechanical and microoptical elements 9,10 . These structures exhibit aspect ratios (ARs) of over 10 and almost vertical sidewalls, making them much more challenging to develop than the structures typically used in planar technology with moderate ARs of 1 to 2. They are therefore characterized by an intermediate state between two-and threedimensional (2D and 3D), that is, a 2D planar design that is extended into the vertical dimension and often called . There are several methods to produce HAR structures on typical planar substrates, most of them relying on the anisotropy of subtractive pattern transfer of a low AR masking layer into an underlying resist or substrate, that is, by using mask based ultraviolet (UV)-photolithography (PL) with an AR up to 5, silicon etching (for example, dry etching) with an AR up to 20, and direct write laser lithography (DWL) and X-ray lithography with ARs 420 (Refs. 12-15). These methods are continually being improved to produce a higher AR and smaller lateral dimensions. Furthermore, they are enlarged by new techniques that are often subsets of etching processes with different advantages and disadvantages. One of those challenges is the suitability for submicron and nanopatterning, that is, structures with lateral sizes much smaller than 1 μm and the possibility to combine micro-with nanostructures in the same material.There are three main approaches: (1)...

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Section: Discussionmentioning

confidence: 99%

High-aspect-ratio nanoimprint process chains

et al. 2017

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“…To improve this issue, we have developed efficient process by using liquid transfer imprint lithography (LTIL) technique. LTIL is one candidate for solving these problems because excess resin is split from the mold in the liquid phase [5][6][7]. As a result, we can obtain five layers stacking of gold dots and silver dots in transparent resin layer [8].…”

Section: Introductionmentioning

confidence: 99%

Metallic Color Filter Fabrication using Photo-Curable Polymer Stacking

Taniguchi

Tsuji

2016

J. Photopol. Sci. Technol.

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Nanoimprint lithography (NIL) can be used as a tool for three-dimensional nanoscale fabrication. In particular, complex metal pattern structures in polymer material are demanded as plasmonic effect devices and metamaterials. To fabricate of metallic color filter, we used silver ink and liquid-transfer imprint lithography (LTIL) techniques. Metallic color filter was composed of stacking of nanoscale silver disc patterns and polymer layers, thus, controlling of polymer layer thickness is necessary. To control of thickness of polymer layer, we used spin-coating of UV-curable polymer and LTIL process. To obtain silver disc pattern, we used silver ink, Ultraviolet NIL technique and LTIL process. As a result, ten stacking layers with 1000 nm layer thickness was obtained and red color was observed. The obtained colors are generated from plasmon phenomenon. This process is very useful to make stacking structure without vacuum environment. Keyword: liquid-transfer imprint lithography, nanoimprint lithography, UV-curable resin, metallic color filter, silver ink IntroductionThere is a growing demand for a nanoscale metal disc stacking technique to fabricate next-generation devices such as plasmonic devices, metamaterials, and memory devices [1][2][3]. In particular, complex three-dimensional (3D) structure is difficult to fabricate. Stacking these metal structures in transparent resin and insulators is usually achieved with lithographic patterning, metal deposition, and a lift-off process: the desired pattern of resin is first fabricated on the substrate, the metal layer is then deposited by thermal evaporation or sputter coating, and the resin is removed by chemical dissolution. Resin patterning is typically performed using electron beam lithography (EBL) or nanoimprint lithography (NIL) [4], but for further efficient fabrication, NIL can also be used to transfer both the metal patterns and the intermediate resin layer. However, it is difficult to control the thickness of the intermediate resin layer with this technique. To improve this issue, we have developed efficient process by using liquid transfer imprint lithography (LTIL)

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“…This layer must be removed in a semiconductor process, so it is desirable that it is as thin as possible. Liquid-transfer imprint lithography (LTIL) is one candidate for solving the residual-layer problem [3]. Although it was first reported as recently as 2013, LTIL is now widely used in a range of applications.…”

Section: Introductionmentioning

confidence: 99%

Outline of Liquid-Transfer Imprint Technology and Advanced Processes

Taniguchi

Unno

2015

J. Photopol. Sci. Technol.

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Nanoimprint lithography can be used as a tool for semiconductor lithography. However, problems still remain in respect of the thickness of the residual layer. Liquid-transfer imprint lithography (LTIL) is one candidate for solving such problems. The principle of LTIL involves partial removal of the UV-curable resin in the liquid phase, permitting control of the thickness of the resin layer on the film mold. After removal of the excess resin, the film mold with a thin layer of UV-curable resin is contacted with the target substrate. This process is very simple, permitting its application in various methods and with various types of equipment, such as roll-to-substrate, roll press, or roll-to-roll machinery. Several types of resin-removal and stacking methods are possible. The machinery and associated techniques have a wide range of applications. LTIL has considerable potential, because transfer with no residual layer is possible, a result that is very useful in semiconductor lithography.

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Liquid transfer imprint lithography: A new route to residual layer thickness control

Cited by 27 publications

References 5 publications

High-aspect-ratio nanoimprint process chains

High-aspect-ratio nanoimprint process chains

Metallic Color Filter Fabrication using Photo-Curable Polymer Stacking

Outline of Liquid-Transfer Imprint Technology and Advanced Processes

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