• Macromolecular Research
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• v.13 no.5
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• pp.435-440
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• 2005

This study describes a method where the match of two different length scales, i.e., the patterns from self-assembled block copolymer (<50 nm) and electron beam writing (>50 nm), allow the nanometer scale pattern mask. The method is based on using block copolymers containing a poly(methyl methacrylate) (PMMA) block, which is subject to be decomposed under an electron beam, as a pattern resist for electron beam lithography. Electron beam on self assembled block copolymer thin film selectively etches PMMA microdomains, giving rise to a polymeric nano-pattern mask on which subsequent evaporation of chromium produces the arrays of Cr nanoparticles followed by lifting off the mask. Furthermore, electron beam lithography was performed on the micropatterned block copolymer film fabricated by micro-imprinting, leading to a hierarchical self assembled pattern where a broad range of length scales was effectively assembled, ranging from several tens of nanometers, through submicrons, to a few microns.

• Elastomers and Composites
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• v.34 no.1
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• pp.45-52
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• 1999

This paper describes how the gold particles self assemble on the specific phase on the microphase separated block copolymer thin film and form a well ordered patterns. For this study, polystyrene-polybutadiene-polystyrene (PS-PB-PS) triblock copolymer (30wt % PS) thin films (${\sim}100nm$) having a cylindrical morphology were cast from 0.1wt% toluene solution to be used as polymer thin film templates. The films having either vertical PS cylinders or in-plane PS cylinders in PB matrix from each different solvent evaporation condition were obtained. Cross-sectional transmission electron microscopy(TEM) was used to study the surface and bulk morphologies of block copolymer thin films. Small amount of gold particles was evaporated on a block copolymer thin film template to obtain a nano-scale pattern. When an as-cast thin film template was used, gold particles preferentially self assemble on the low surface tension PB phase and a relatively well ordered pattern in nano-scale was produced. However, after the formation of a low surface energy PB rich layer upon annealing, a gold self-assembled pattern was not observed.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2004.05a
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• pp.243-243
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• 2004

상용화된 주사식 전자현미경(SEM)을 기본 구조로 하는 가공 시스템을 구축하여 전자빔(Electron beam)을 이용한 초미세 패턴(Nano pattern) 등 형상의 직접 성형, 혹은 직접 묘화(Direct writing) 가공을 수행하기 위해서는 크게 분류하여 연속적으로 스캐닝되는 전자빔을 요구에 따라 적절하게 극히 짧은 시간 내에 개폐하는 빔 블랭커(Beam blanker)와 효율적으로 초미세 패턴 등의 형상을 설계ㆍ가공하기 위한 전용 S/W의 두 가지 요소가 반드시 적용되어야 한다.(중략)

• Journal of the Korean Society for Precision Engineering
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• v.20 no.9
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• pp.47-54
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• 2003

In this study, to achieve the optimal conditions for mechanical hyper-fine pattern fabrication process, deformation behavior of the materials during indentation was studied with numerical method by ABAQUS S/W. Polymer (PMMA) and brittle materials (Si, Pyrex glass) were used as specimens, and forming conditions to reduce the elastic re cover and pile-up were proposed. The indenter was modeled a rigid surface. Minimum mesh sizes of specimens are 1 -l0nm. Comparison between the experimental data and numerical result demonstrated that the finite element approach is capable of reproducing the loading-unloading behavior of a nanoindentation test. The result of the investigation will be applied to the fabrication of the hyper-fine pattern.

• Proceedings of the Materials Research Society of Korea Conference
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• 2009.05a
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• pp.12.1-12.1
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• 2009

For the micro conductive line, memory device fabrication process use many expensive processes such as manufactur-ing of photo mask, coating of photo resist, exposure, development, and etching. However, direct printing technology has the merits about simple and cost effective processes because nano-metal particles contained inks are directly injective without mask. And also, this technology has the advantage about fabrication of fine pattern line on various substrates such as FPCB, PCB, glass, polymer and so on. In this work, we have fabricated the fine and thick metal pattern line on flexible PCB substrate for the next generation electronic circuit using Ag nano-particles contained ink. To improve the line tolerance on flexible PCB, metal lines are fabricated by sequential prinitng method. Sequential printing method has vari-ous merits about fine, thick and high resolution pattern lines without bulge.

• Proceedings of the Materials Research Society of Korea Conference
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• 2003.11a
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• pp.71-71
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• 2003

Hot embossing has been widely accepted as an alternative to photolithography in generating patterns on polymeric substrates. The optimization of embossing process should be accomplished based on polymer substrate materials. In this paper, the effect of polymer substrates on nano scale hot embossing process was studied. Silicon molds with nano size patterns were fabricated by e-beam direct writing. Molds were coated with self-assembled monolayer (SAM) of (1, 1, 2.2H -perfluorooctyl)-trichlorosilane to reduce the stiction between mold and substrates. For an embossing, pressure of 55, 75 bur, embossing time of 5 min and temperature of above transition temperature were peformed. Polymethylmethacrylates (PMMA) with different molecular weights of 450,000 and 950,000, MR-I 8010 polymer (Micro Resist Technology) and polyaliphatic imide copolymer were applied for hot embossing process development in nano size. These polymers were spun coated on the Si wafer with the thickness between 150 and 200 nm. The nano size patterns obtained after hot embossing were observed and compared based on the polymer properties by scanning electron microscopy (SEM). The imprinting uniformity dependent on the Pattern density and size was investigated. Four polymers have been evaluated for the nanoimprint By optimizing the process parameters, the four polymers lead to uniform imprint and good pattern profiles. A reduction in the friction for smooth surfaces during demoulding is possible by polymer selection.

• Journal of Industrial Technology
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• v.39 no.1
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• pp.33-39
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• 2019

This paper addresses effects of nanoscale structures on structural colors of micropatterned transparent substrate by light diffraction. Structural colors is widely investigated because they present colors without any chemical pigments. Typically structural colors is presented by diffraction of light on a micropatterned surface or by multiple interference of light on a surface containing a periodic or quasi-periodic nano-structures. In this paper, each structural colors induced by quasi-periodic nano-structures, periodic micro-structures, and nano/micro dual structures is measured in order to investigate effects of nanoscale and microscale structures on structural colors in the transparent substrate. Using pre-fabricated pattern mold and hot-embossing process, nanoscale and microscale structures are replicated on the transparent PMMA(Poly methyl methacrylate) substrate. Nanoscale and microscale pattern molds are prepared by anodic oxidation process of aluminum sheet and by reactive ion etching process of silicon wafer, respectively. Structural colors are captured by digital camera, and their optical transmittance spectrum are measured by UV/visible spectrometer. From experimental results, we found that nano-structures provide monotonic colors by multiple interference, and micro-structures induce iridescent colors by diffraction of light. Structural colors is permanent and unchangeable, thus it can be used in various application field such as security, color filter and so on.

• Current Optics and Photonics
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• v.2 no.6
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• pp.540-546
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• 2018

We propose an implementation scheme for an optical encryption system with hybrid-pattern random keys. In the encryption process, a pair of random phase keys composed of a white-noise phase key and a structured phase key are positioned in the input plane and Fourier-spectrum plane respectively. The output image is recoverable by digital reconstruction, using the conjugate of the encryption key in the Fourier-spectrum plane. We discuss the system encryption performance when different combinations of phase-key pairs are used. To measure the effectiveness of the proposed method, we calculate the statistical indicators between original and encrypted images. The results are compared to those generated from a classical double random phase encoding. Computer simulations are presented to show the validity of the method.

• Journal of the Korean Society for Precision Engineering
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• v.25 no.4
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• pp.134-139
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• 2008

A spirally arrayed nano-pattern is designed as a model pattern for the next generation optical storage media. The pattern consists off types of embossed rectangular dot, which are 50nm, 100nm, 150nm and 200nm in length and 50nm in width. The height of the dot is designed to be 50nm. The pitch of the spiral track of the pattern is 100nm. A ER(Electron resist) master for this pattern is fabricated by e-beam lithography process. The ER is first spin-coated to be 50nm thick on a Si wafer and then the model pattern is written on the coated ER layer by e-beam. After developing this pattern written wafer in the solution, a ER pattern master is fabricated. The most conventional e-beam machine can write patterns in orthogonal way, so we made our own pattern generator which can write the pattern in circular or spiral way. This program generates the patterns to be compatible with the e-beam machine from Raith(Raith 150). To fabricate 50nm pattern master precisely, a series of experiments were done including the design compensation for the pattern size, optimization of the dose, acceleration voltage, aperture size and developing. Through these experiments, we conclude that the higher accelerating voltages and smaller aperture size are better for mastering the nano pattern which is in order of 50nm. With the optimized e-beam lithography process, a spiral arrayed 50nm pattern master adopting PMMA resist was fabricated to have dimensional accuracy over 95% compared to the designed. Using this pattern master, a metal pattern stamp will be fabricated by Ni electro plating for injection molding of the patterned plastic substrate.

• Korean Journal of Optics and Photonics
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• v.18 no.2
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• pp.149-154
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• 2007

Bragg reflecting waveguide devices have been fabricated on a flexible polymer substrate utilizing a post lift-off process which could Provide excellent uniformity of grating Patterns on Plastic film. The 510 m Period Bragg grating pattern is made by two methods. In the first sample the grating is fabricated by exposing the laser interference pattern on a photoresist, and then it is inscribed by $O_2$ plasma etching. The grating pattern of the second sample is formed by a PDMS soft mold imprinting process. The selective adhesion property of SU-8 material for Au and Si surfaces is utilized to prepare a 100-mm thick plastic substrate. Single mode waveguide is fabricated on the plastic substrate using polymer materials with refractive indices of 1.540 and 1.430 for the core and the cladding layers, respectively. The Bragg grating on Plastic substrate does not show any degradation in its spectral response compared to the reference sample made on a silicon wafer.