• Journal of the Microelectronics and Packaging Society
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• v.29 no.1
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• pp.55-59
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• 2022

In this paper, we compared the electric field and absorptance of nano particles in nanostructures by amplifying the electric field around the nanoparticles through plasmon resonance and comparing the structure that can increase the absorptance with the nanostructure by using the Finite Different Time Domain (FDTD) simulation. In addition, the width of the nanostructure was adjusted to 240 nm ~ 300 nm, and the light absorptance rate was higher as the gap between the particles was short. In addition, a study was conducted on the formation of nanoparticles and nanostructures on the surface through UV imprint. In order to form particles in the structure, the nano particles were first arranged in the mold used for the fabrication of the structure using spray coating, and then fabricated through UV imprinting. The nanostructure and particles were formed together by scanning electron microscopy.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.16 no.1
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• pp.8-17
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• 2023

In conventional liquid crystal display(LCD) manufacturing process, Indium Tin Oxide(ITO) as transparent electrode and rubbing process of polyimide as alignment layer are essential process to apply electric field and align liquid crystal molecules. However, there are some limits that deposition of ITO requires high vacuum state, and rubbing process might damage the device with tribolectric discharge. In this paper, we made nanocomposite with PEDOT:PSS and MWNT to replace ITO and constructed alignment layer by nano imprint lithography with nano wrinkle pattern, to replace rubbing process. These replacement made that only one PEDOT:PSS/MWNT film can function as two layers of ITO and polyimide alignment layer, which means simplification of process. Transferred nano wrinkle patterns functioned well as alignment layer, and we found out lowered threshold voltage and shortened response time as MWNT content increase, which is related to increment of electric conductivity of the film. Through this study, it may able to contribute to process simplification, reducing process cost, and suggesting a solution to disadvantage of rubbing process.

• Korean Chemical Engineering Research
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• v.45 no.2
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• pp.149-154
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• 2007

Nanoimprint lithography (NIL) is useful technique because of its low cost and high throughput capability for the fabrication of sub-micrometer patterns which has potential applications in micro-optics, magnetic memory devices, bio sensors, and photonic crystals. Usually, a chemical surface treatment of the stamp is needed to ensure a clean release after imprinting and to protect the expensive original master against contamination. Meanwhile, adhesion promoter between resin and substrate is also important in the nanoscale pattern. In this work, we have investigated the effect of surface treatment using silane coupling agent as release layer and adhesion promoter for UV-Nanoimprint lithography. Uniform SAM (self-assembled monolayer) could be fabricated by vapor deposition method. Vapor phase process eliminates the use of organic solvents and greatly simplifies the handling of the sample. It was also proven that 3-acryloxypropyl methyl dichlorosilane (APMDS) could strongly improve the adhesion force between resin and substrate compared with common planarization layer such as DUV-30J or oxygen plasma treatment.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.4
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• pp.1838-1843
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• 2014

Nanoimprint lithography (NIL) fabrication process is regarded as the main alternative to existing expensive photo-lithography in areas such as micro- and nano-electronics including optical components and sensors, as well as the solar cell and display device industries. Functional patterns, including anti-reflective moth-eye pattern, photonic crystal pattern, fabricated by NIL can improve the overall efficiency of such devices. To successfully imprint a nano-sized pattern, the process conditions such as temperature, pressure, and time should be appropriately selected. In this paper, a cavity-filling process of the moth-eye pattern during the thermal-NIL within the temperature range, where the polymer resist shows the viscoelastic behaviors with consideration of stress relaxation effect of the polymer, were investigated with three-dimensional finite element analysis. The effects of initial thickness of polymer resist and imprinting pressure on cavity-filling process has been discussed. From the analysis results it was found that the cavity filling can be completed within 100 s, under the pressure of more than 4 MPa.

• Proceedings of the Korean Vacuum Society Conference
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• 2015.08a
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• pp.189-189
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• 2015

Plasmonics, sensor, field effect transistors, solar cells 등 다양한 적용분야를 가지는 실리콘 구조체는 제작공정에 의해 전기적 및 광학적 특성이 달라지기 때문에 적합한 나노구조 제작방법이 요구되고 있다. 나노구조체 제작방법으로는 Photo lithography, Extreme ultraviolet lithography (EUV), Nano imprinting lithography (NIL), Block copolymer (BCP) 방식의 방법들이 연구되고 있으며, 특히 BCP는 direct self-assembly 특성을 가지고 있으며 가격적인 면에서도 큰 장점을 가진다. 하지만 BCP를 mask로 사용하여 식각공정을 진행할 경우 BCP가 버티지 못하고 변형되어 mask로서의 역할을 하지 못한다. 이러한 문제를 해결하기 위하여 본 논문에서는 BCP와 질화막을 이용한 double mask 방법을 사용하였다. 기판 위에 BCP를 self-assembly 시키고 mask로 사용하여 hole 부분으로 노출된 기판을 Ion gun을 통해 질화 시킨 후에 BCP를 제거한다. 기판 위에 hole 모양의 질화막 표면은 BCP와 다르게 etching 공정 중 변형되지 않는다. 이러한 질화막 표면을 mask로 사용하여 pillar pattern의 실리콘 나노구조체를 제작하였다. 질화막 mask로 사용되는 template은 PS와 PMMA로 구성된 BCP를 사용하였다. 140kg/mol의 polystyrene과 65kg/mol의 PMMA를 톨루엔으로 용해시키고 실리콘 표면 위에 spin coating으로 도포하였다. Spin coat 후 230도에서 40시간 동안 열처리를 진행하여 40nm의 직경을 가진 PS-b-PMMA self-assembled hole morphology를 형성하였다. 질화막 형성 및 etching을 위한 장비로 low-energy Ion beam system을 사용하였다. Reactive Ion beam은 ICP와 3-grid system으로 구성된 Ion gun으로부터 형성된다. Ion gun에 13.56 MHz의 frequency를 갖는 200W 전력을 인가하였다. Plasma로부터 나오는 Ion은 $2{\Phi}$의 직경의 hole을 가지는 3-grid hole로 추출된다. 10~70 voltage 범위의 전위를 plasma source 바로 아래의 1st gird에 인가하고, 플럭스 조절을 위해 -150V의 전위를 2nd grid에 인가한다. 그리고 3rd grid는 접지를 시켰다. chamber내의 질화 및 식각가스 공급은 2mTorr로 유지시켰다. 그리고 기판의 온도는 냉각칠러를 이용하여 -20도로 냉각을 진행하였다. 이와 같은 공정 결과로 100 nm 이상의 높이를 갖는 40 nm직경의 균일한 Silicon pillar pattern을 형성 할 수 있었다.

• Journal of Powder Materials
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• v.24 no.6
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• pp.464-471
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• 2017

A metal mesh TCE film is fabricated using a series of processes such as UV imprinting of a transparent trench pattern (with a width of $2-5{\mu}m$) onto a PET film, filling it with silver paste, wiping of the surface, and heat-curing the silver paste. In this work nanosized (40-50 nm) silver particles are synthesized and mixed with submicron (250-300 nm)-sized silver particles to prepare silver paste for the fabrication of metal mesh-type TCE films. The filling of these silver pastes into the patterned trench layer is examined using a specially designed filling machine and the rheological testing of the silver pastes. The wiping of the trench layer surface to remove any residual silver paste or particles is tested with various mixture solvents, and ethyl cellosolve acetate (ECA):DI water = 90:10 wt% is found to give the best result. The silver paste with 40-50 nm Ag:250-300 nm Ag in a 10:90 wt% mixture gives the highest electrical conductance. The metal mesh TCE film obtained with this silver paste in an optimized process exhibits a light transmittance of 90.4% and haze at 1.2%, which is suitable for TSP application.

• Proceedings of the Korean Vacuum Society Conference
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• 2014.02a
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• pp.413-413
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• 2014

In this paper, we present a fabrication method of functionalized gold nanostructures on flexible substrate that can be implemented for plasmonic sensing application. For biomolecular sensing, many researchers exploit unconventional lithography method like nanoimprint lithography (NIP), contact transfer lithography, soft lithography, colloidal transfer printing due to its usability and easy to functionalization. In particular, nanoimprint and contact transfer lithography need to have anti-adhesion layer for distinctive metallic properties on the flexible substrates. However, when metallic thin film was deposited on the anti-adhesion layer coated substrates, we discover much aggravation of the mold by repetitive use. Thus it would be impossible to get a high quality of metal nanostructure on the transferred substrate for developing flexible electronics based transfer printing. Here we demonstrate a method for nano-pillar mold and transfer the controllable nanoparticle array on the flexible substrates without an anti-adhesion layer. Also functionalization of gold was investigated by the different length of thiol applied for effectively localized surface plasmonic resonance sensing. First, a focused ion beam (FIB) and ICP-RIE are used to fabricate the nanoscale pillar array. Then gold metal layer is deposited onto the patterned nanostructure. The metallic 130 nm and 250 nm nanodisk pattern are transferred onto flexible polymer substrate by bi-layer functionalized contact imprinting which can be tunable surface energy interfaces. Different thiol reagents such as Thioglycolic acid (98%), 3-Mercaptopropionic acid (99%), 11-Mercaptoundecanoic acid (95%) and 16-Mercaptohexadecanoic acid (90%) are used. Overcoming the repeatedly usage of the anti-adhesion layer mold which has less uniformity and not washable interface, contact printing method using bi-layer gold array are not only expedient access to fabrication but also have distinctive properties including anti-adhesion layer free, functionalized bottom of the gold nano disk, repeatedly replicate the pattern on the flexible substrate. As a result we demonstrate the feasibility of flexible plasmonic sensing interface and anticipate that the method can be extended to variable application including the portable bio sensor via mass production of stable nanostructure array and other nanophotonic application.