• Journal of the Semiconductor & Display Technology
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• v.14 no.3
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• pp.61-66
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• 2015

Recently, the major trends of NIL are high throughput and large area patterning. For UV NIL, if it can be proceeded in the non-vacuum environment, which greatly simplifies tool construction and greatly shorten process times. However, one key issue in non-vacuum environment is air bubble formation problem. In this paper, numerical analysis of bubble defect of UV NIL is performed. Fluent, flow analysis focused program was utilized and VOF (Volume of Fluid) skill was applied. For various resist-substrate and resist-mold angles, effects of velocity inlet and residual layer thickness of resist on bubble defect formation were investigated. The numerical analyses show that the increases of velocity inlet and residual layer thickness can cause the bubble defect formation, however the decreases of velocity inlet and residual layer thickness take no difference in the bubble defect formation.

• Journal of Information Display
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• v.11 no.2
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• pp.49-51
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• 2010

Nanoimprint lithography (NIL) using ultraviolet (UV) rays is a technique in which unconventional lithographic patterns are formed on a substrate by curing a suitable liquid resist in contact with a transparent patterned mold, then releasing the freshly patterned material. Here, various solutions are introduced to achieve sufficient overlay accuracy and to overcome the technical challenges in resist patterning via UV imprinting. Moreover, resist patterning of all the layers in TFT and of the BM layer in CF was carried out using UV imprinting lithography to come up with a 12.1-inch TFT-LCD panel with a resolution of $1280{\times}800$ lines (125 ppi).

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.12 no.5
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• pp.30-35
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• 2013

In order to increase cell efficiency in crystalline silicon solar cell, reduction of light reflection is one of the essential problem. Until now silicon wafer was textured by wet etching process which has random patterns along crystal orientation. In this study, high aspect ratio patterns are manufactured by nano imprint process and reflectance could be minimized under 1%. After that, screen printed solar cell was fabricated on the textured wafer and I-V characteristics was measured by solar simulator. Consequently cell efficiency of solar cell fabricated using the wafer textured by nano imprint process increased 1.15% than reference solar cell textured by wet etching. Internal quantum efficiency was increased in the range of IR wave length but decreased in the UV wavelength. In spite of improved result, optimization between nano imprinted pattern and solar cell process should be followed.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2012.05a
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• pp.153-153
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• 2012

자연계에는 다양한 생물체들의 표면 구조가 특수한 기능을 갖는 형태로 되어 있다. 이와 같이 특수한 기능을 갖는 생물체들의 표면 구조는 일반적으로 화학적 조성과 표면의 더불어 나노와 마이크로 구조가 혼합되어 있는, 이른바 hierarchical 구조를 보인다. 그 중에서도 표면 초소수성 특성을 보이는 연잎의 표면과 같은 hierarchical 구조는 self-cleaning effect 등의 기능성 표면 제작에 활용이 가능하여 이를 모사하기 위한 연구가 활발히 진행중에 있다. 이에 본 연구에서는 연잎과 같은 초소수성을 띄는 ZnO nano-in-micro hierarchical 구조를 저온 공정을 통하여 다양한 기판에 제작하였다. 이를 위하여 ZnO 나노 입자 분산 레진을 제작하였고 UV imprinting 과 수열합성법을 통하여 마이크로 패턴 상부에 ZnO 나노 입자가 형성된 ZnO nano-in-micro hierarchical 구조를 형성하였다. 제작된 ZnO hierarchical 구조의 젖음 특성은 표면 접촉각이 $160^{\circ}C$이상인 초소수성을 보였으며, 제작 공정에는 고온의 열처리가 수반되지 않아 PET film 등 다양한 기판에 ZnO hierarchical 구조를 제작할 수 있었다.

• Korean Journal of Optics and Photonics
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• v.28 no.2
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• pp.53-58
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• 2017

This paper presents the design and fabrication of a planar nano-diffraction grating for an integrated miniature spectrometer module. The proposed planar nano-diffraction grating consists of nonuniform periods, to focus the reflected beams from the grating's surface, and an asymmetrical V-shaped groove profile, to provide uniform diffraction efficiency in the wavelength range from 400 to 650 nm. Also, to fabricate the nano-diffraction grating using low-cost UV-NIL technology, we analyzed the FT-IR spectrum of a uvcurable resin and optimized the conditions for the UV curing process. Then, we precisely fabricated the polymeric nano-diffraction grating within 5 nm in dimensional accuracy. The integrated spectrometer module using the fabricated polymeric planar nano-diffraction grating provides spectral resolution of 5 nm and spectral bandwidth of 250 nm. Our integrated spectrometer module using a polymeric planar nano-diffraction grating serves as a quick and easy solution for many spectrometric applications.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2009.05a
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• pp.78-83
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• 2009

In general, Light-hardening polymer was used UV nanoimprint technology. A light-hardening polymer was had the problem of poor hardness, durability. In order to overcome the problem of polymer, inter change optical glass. However glass is very manufacture and a lowering of standars transmittance. In order to glass recover was necessary polishing process. The process is magnetorheological fluids polishing. MR polishing has been developed as a new precision finishing technique to obtain a fine surface. Hence, Magnetorheological fluids has been used for micro polishing to get micro parts. This polishing process guarantees high polishing quality by controlling the fluid density electrically. The applied material in experiments is fused silica glass. Fused silica glass is widely used in the optical field because of high degree of purity. For MR polishing experiments, MR fluid was composed with DI-water, carbonyl iron and nano slurry ceria. The wheel speed and electric current were chosen as the variables for analyzing the characteristics of MR polishing process. Outstanding surface roughness of Ra=1.58nm was obtained on the fused silica glass specimen. And originally glass transmittance was recover on the fused silica glass.

• Proceedings of the Materials Research Society of Korea Conference
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• 2009.05a
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• pp.21.2-21.2
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• 2009

발광다이오드는 에너지 변환 효율이 높고 친환경적인 장점으로 인하여 차세대 조명용 광원으로 각광받고 있다. 하지만 현재 발광다이오드는 낮은 광추출효율로 인하여 미래의 수요를 충족시킬 수 있을 만큼 충분한 성능의 효율을 나타내지 못하고 있다. 발광다이오드의 낮은 광추출효율은 반도체소재와 외부 공기와의 큰 굴절률 차이로 인하여 발생하는 전반사 현상에 기인한 것으로 이 문제를 해결하기 위하여 발광다이오드 소자의 발광면 및 기판을 텍스처링하는 방법이 중요하게 인식되고 있다. 하지만 현재까지 패턴의 구조에 따른 광추출 특성을 분석한 연구는 미진한 상황이다. 본 연구에서는 임프린팅 및 건식식각 공정을 이용하여 다양한 구조의 나노 및 micron 급 패턴을 발광다이오드의 p-GaN층에 형성하였다. 발광다이오드 기판 위에 하드마스크로 사용하기 위한 SiO2를 50nm 증착한 후 그 위에 UV 임프린팅 공정을 진행하여 폴리머 패턴을 형성시켰다. 임프린팅 공정으로 형성된 폴리머 패턴을 CF4CHF3 플라즈마를 이용하여 SiO2를 건식식각하였고, 이후에 SiCl4와 Ar 플라즈마를 이용한 ICP 식각 공정을 진행하여 p-GaN층을 100nm 식각하였다. 마지막으로 BOE를 이용한 습식식각 공정으로 p-GaN층에 남아있는 SiO2층을 제거하여 p-GaN층에 sub-micron에서 micron급의 홀 패턴을 형성하였다. Photoluminescence(PL) 측정을 통해서 발광다이오드 소자에 형성된 패턴의 구조에 따른 광추출 특성을 분석하였다.

• Korean Journal of Materials Research
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• v.16 no.4
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• pp.225-230
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• 2006

Nanoimprint lithography (NIL) is a novel method of fabricating nanometer scale patterns. It is a simple process with low cost, high throughput and resolution. NIL creates patterns by mechanical deformation of an imprint resist and physical contact process. The imprint resist is typically a monomer or polymer formulation that is cured by heat or UV light during the imprinting process. Stiction between the resist and the stamp is resulted from this physical contact process. Stiction issue is more important in the stamps including narrow pattern size and wide area. Therefore, the antistiction layer coating is very effective to prevent this problem and ensure successful NIL. In this paper, an antistiction layer was deposited and characterized by PECVD (plasma enhanced chemical vapor deposition) method for metal stamps. Deposition rates of an antistiction layer on Si and Ni substrates were in proportion to deposited time and 3.4 nm/min and 2.5 nm/min, respectively. A 50 nm thick antistiction layer showed 90% relative transmittance at 365 nm wavelength. Contact angle result showed good hydrophobicity over 105 degree. $CF_2$ and $CF_3$ peaks were founded in ATR-FTIR analysis. The thicknesses and the contact angle of a 50 nm thick antistiction film were slightly changed during chemical resistance test using acetone and sulfuric acid. To evaluate the deposited antistiction layer, a 50 nm thick film was coated on a stainless steel stamp made by wet etching process. A PMMA substrate was successfully imprinting without pattern degradations by the stainless steel stamp with an antistiction layer. The test result shows that antistiction layer coating is very effective for NIL.

• Journal of the Microelectronics and Packaging Society
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• v.30 no.2
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• pp.65-70
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• 2023

Nanoimprint lithography (NIL) has attracted much attention due to its process simplicity, excellent patternability, process scalability, high productivity, and low processing cost for pattern formation. However, the pattern size that can be implemented on metal materials through conventional NIL technologies is generally limited to the micro level. Here, we introduce a novel hard imprint lithography method, extreme-pressure imprint lithography (EPIL), for the direct nano-to-microscale pattern formation on the surfaces of metal substrates with various thicknesses. The EPIL process allows reliable nanoscopic patterning on diverse surfaces, such as polymers, metals, and ceramics, without the use of ultraviolet (UV) light, laser, imprint resist, or electrical pulse. Micro/nano molds fabricated by laser micromachining and conventional photolithography are utilized for the nanopatterning of Al substrates through precise plastic deformation by applying high load or pressure at room temperature. We demonstrate micro/nanoscale pattern formation on the Al substrates with various thicknesses from 20 ㎛ to 100 mm. Moreover, we also show how to obtain controllable pattern structures on the surface of metallic materials via the versatile EPIL technique. We expect that this imprint lithography-based new approach will be applied to other emerging nanofabrication methods for various device applications with complex geometries on the surface of metallic materials.