• Proceedings of the Korean Society of Precision Engineering Conference
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• 2003.06a
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• pp.199-202
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• 2003

Ultraviolet-nanoimprint lithography (UV-NIL) is a promising method for cost-effectively defining nanoscale structures at room temperature and low pressure. Since the resolution of nanostructures depends strongly upon that of nanostamps, the nanostamp fabrication technology is a key technology to UV-NIL. In this paper, a 5$\times$5$\times$0.09 in. quartz stamp whose critical dimension is 377 nm was fabricated using the etch process in which a Cr film was employed as a hard mask for transferring nanostructures onto the quartz plate. To effectively apply tile fabricated 5-in. stamp to UV-NIL on a 4-in. Si wafer, we have proposed a new UV-NIL process using a multi-dispensing method as a way to supply resist on a wafer Experiments have shown that the multi-dispensing method can enable UV-NIL rising a large-area stamp.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2007.05a
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• pp.199-204
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• 2007

Hot embossing, one of Nanoimprint Lithography(NIL) techniques, has been getting attention as an alternative candidate of next generation patterning technologies by the advantages of simplicity and low cost compared to conventional photolithographies. A typical hot embossing usually, however, takes more than ten minutes for one cycle of the process because of a long thermal cycling. Over the last few years a number of studies have been made to reduce the cycle time for hot embossing or similar patterning processes. The target of this research is to develop an induction heating apparatus for heating a metallic micro patterning mold at very high speed with the large-area uniformity of temperature distribution. It was found that a 0.5 mm-thick nickel mold can be heated from $25^{\circ}C$ to $150^{\circ}C$ within 1.5 seconds with the temperature variation of ${\pm}5^{\circ}C$ in 4-inch diameter area, using the induction heating apparatus.

• Proceedings of the KSME Conference
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• 2003.04a
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• pp.1078-1082
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• 2003

A feasibility study for the fabrication of master replication with nanostructures by Nanoimprint Lithography (NIL) was investigated for application of polymer Photonic Bandgap (PBG) devices used in photonic IC. Large area gratings of $9{\times}15(mm^2)$ with p = 400 nm was successfully embossed on PMMA on silicon wafer and the embossing parameters (temperature, pressure, time) were established. A precise control of $O_2$ plasma Reactive Ion Etching (RIE) process time allowed window opening over the whole area despite the presence of wafer bending. Master replication with aspect ratio 1 was successfully fabricated, but master replication with aspect ratio 3 needs to optimize parameters. All replications were done in a NIL process.

• Korean Journal of Materials Research
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• v.26 no.11
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• pp.635-643
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• 2016

Graphene has shown exceptional properties for high performance devices due to its high carrier mobility. Of particular interest is the potential use of graphene nanoribbons as field-effect transistors. Herein, we introduce a facile approach to the fabrication of graphene nanoribbon (GNR) arrays with ~200 nm width using nanoimprint lithography (NIL), which is a simple and robust method for patterning with high fidelity over a large area. To realize a 2D material-based device, we integrated the graphene nanoribbon arrays in field effect transistors (GNR-FETs) using conventional lithography and metallization on highly-doped $Si/SiO_2$ substrate. Consequently, we observed an enhancement of the performance of the GNR-transistors compared to that of the micro-ribbon graphene transistors. Besides this, using a transfer printing process on a flexible polymeric substrate, we demonstrated graphene-silicon junction structures that use CVD grown graphene as flexible electrodes for Si based transistors.

• Journal of the Semiconductor & Display Technology
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• v.15 no.2
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• pp.74-80
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• 2016

This study presents a thermal device specially designed for thermal nanoimprint lithography equipments, which requires the capability of rapid heating and cooling, high temperature uniformity and the material strength to endure high stamping pressure. The proposal to meet these requirements is a planar-type hot plate extensible to a large area, in which long circular cartridge heaters and heat pipes are installed inside in parallel. The heat pipes are connected to the outside water cooling chamber. A hot plate made of stainless steel is fabricated with a dimension $240mm{\times}240mm{\times}20mm$. Laboratory experiments are conducted to examine the thermal performance of the hot plate. The results illustrate that the employment of heat pipes leads to a notable enhancement of temperature uniformity in the device and provides an efficient heat delivery from the hot plate to outside. It is verified that the suggested hot plate could be a feasible thermal tool for thermal nanoimprint lithography, satisfying the major design requirements.

• Advances in nano research
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• v.13 no.2
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• pp.199-206
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• 2022

We present the high-brightness large-area 10.1" in-cell polarizer display panel integrated with a wire grid polarizer (WGP) and metal reflector, from the initial design to final system development in a commercially feasible level. We have modeled and developed the WGP architecture integrated with the metal reflector in a single in-cell layer, to achieve excellent polarization efficiency as well as brightness enhancement through the light recycling effect. After the optimization of key experimental parameters via Taguchi method, the roll nanoimprint lithography employing a flexible large-area tiled mold has been utilized to create the 90 nm-pitch polymer resist pattern with the 54.1 nm linewidth and 5.1 nm residual layer thickness. The 90 nm-pitch Al gratings with the 51.4 nm linewidth and 2150 Å height have been successfully fabricated after subsequent etch process, providing the in-cell WGPs with high optical performance in the entire visible light regime. Finally we have integrated the WGP in a commercial 10.1" display device and demonstrated its actual operation, exhibiting 1.24 times enhancement of brightness compared to a conventional film polarizer-based one, with the contrast ratio of 1,004:1. Polarization efficiency and transmittance of the developed WGPs in an in-cell polarizer panel achieve 99.995 % and 42.3 %, respectively.

• Journal of the Korean Society for Precision Engineering
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• v.24 no.12
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• pp.136-142
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• 2007

Precise fabrication of three-dimensional (3D) self-standing microstructures on thin glass plates via two-photon induced polymerization (TPP) has been an important issue for innovative 3D nanodevices and microdevices. However, there are still issues remaining to be solved, such as building 3D microstructures on opaque materials via TPP and being able to implant them as functional parts onto practical systems. To settle these issues simply and effectively, we propose a contact print lithography (CPL) method using an ultraviolet (UV)-curable polymer layer. We report some of the possibilities and potential of CPL by presenting our results for transplanting 3D microstructures onto large-area substrates and also our examination of some of the effects of the process parameters on successful transplantation.

• 한국정보디스플레이학회:학술대회논문집
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• 2008.10a
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• pp.82-85
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• 2008

We are working towards large-area arrays of thin film transistors on polymer substrates using roll-to-roll (R2R) processes exclusively. Self-aligned imprint lithography (SAIL) is an enabler to pattern and align submicron features on meter-scaled flexible substrates in the R2R environment. The progress, current status and remaining issues of this new fabrication technology are presented.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.29 no.9 s.240
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• pp.1169-1174
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• 2005

Imprint lithography is a promising method for high-resolution and high-throughput lithography using low-cost equipment. In particular, ultraviolet-nanoimprint lithography (UV-NIL) is applicable to large area imprint easily. We have proposed a new UV-NIL process using an elementwise patterned stamp (EPS), which consists of a number of elements, each of which is separated by channel. Experiments on UV-NIL are performed on an EVG620-NIL using the EPS with 3mm channel width. The replication of uniform sub 70 nm lines using the EPS is demonstrated. We investigate the nonuniformity of residual layer caused by wafer deformation in experiment with varying wafer thickness. Severely deformed wafer works as an obstacle in spreading of dropped resin, which causes nonuniformity of thickness of residual layer. Numerical simulations are conducted to analyze aforementioned phenomenon. Wafer deformation in the process is simulated by using a simplified model, which is a good agreement with experiments.

• Korean Journal of Materials Research
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• v.20 no.10
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• pp.550-554
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• 2010

This work presents a fabrication procedure to make large-area, size-tunable, periodically different shape metal arrays using nanosphere lithography (NSL) combined with ashing and annealing. A polystyrene (PS, 580 ${\mu}m$) monolayer, which was used as a mask, was obtained with a mixed solution of PS in methanol by multi-step spin coating. The mask morphology was changed by oxygen RIE (Reactive Ion Etching) ashing and temperature processing by microwave heating. The Au or Pt deposition resulted in size tunable nano patterns with different morphologies such as hole and dots. These processes allow outstanding control of the size and morphology of the particles. Various sizes of hole patterns were obtained by reducing the size of the PS sphere through the ashing process, and by increasing the size of the PS sphere through annealing treatment, which resulted in tcontrolling the size of the metallic nanoparticles from 30 nm to 230 nm.