• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2005.10a
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• pp.63-66
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• 2005

Nanoimprint lithography (NIL) process at room temperature has been newly proposed in recent years to overcome the shape accuracy and sticking problem induced in a conventional NIL process. Success of the room temperature NIL relies on the accurate understand of the mechanical behavior of the polymer. Since a conventional NIL process has to heat a polymer above the glass transition temperature to deform the physical shape of the polymer with a mold pattern, viscoelastic property of polymer have major effect on the NIL process. However, rate dependent behavior of polymer is important in the room temperature NIL process because a mold with engraved patterns is rapidly pressed onto a substrate coated with the polymer by the hydraulic equipment. In this paper, finite element analysis of the room temperature NIL process is performed with considering the strain rate dependent behavior of the polymer. The analyses with the variation of imprinting speed and imprinting pattern are carried out in order to investigate the effect of such process parameters on the room temperature NIL process. The analyses results show that the deformed shape and imprint force is quite different with the variation of punch speed because the dynamic behavior of the polymer is considered with the rate dependent plasticity model. The results provide a guideline for the determination of process conditions in the room temperature NIL process.

• Tribology and Lubricants
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• v.26 no.5
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• pp.297-302
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• 2010

This study is focused on the resin layer formation of UV imprinting process by changing imprinting pressure and period. The mold shape is made for the process of window open over the pattern transfer area and the imprinting period is assigned as the time just before the UV light curing. The residual layer is measured by changing the imprinting period and pressure magnitude, and the measured data of residual layer provides useful information for the design of the process conditions of imprinting processes.

• Proceedings of the KIEE Conference
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• 2001.07d
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• pp.2383-2385
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• 2001

Laser texturing process for the strip casting-roll is investigated and is realized using PC system and Argon Ion Laser. This laser system can imprint any dimple of patterns on the roll-surface with the resolution of ${\mu}m$ unit.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2007.10a
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• pp.364-367
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• 2007

In nano-imprint lithography (NIL) process, which has shown to be a good method to fabricate polymeric patterns, several kinds of pattern defects due to thermal effects during polymer flow and mold release operation have been reported. A typical defect in NIL process with high aspect ratio and low resist thickness pattern is a resist fracture during the mold release operation. It seems due to interfacial adhesion between polymer and mold. However, in the present investigation, FEM simulation of NIL molding process was carried out to predict the defects of the polymer pattern and to optimize the process by FEA. The embossing operation in NIL process was investigated in detail by FEM. From the analytical results, it was found that the lateral flow of polymer resin and the applied pressure in the embossing operation induce the weld line and the drastic lateral strain at the edge of pattern. It was also shown that the low polymer-thickness result in the delamination of polymer from the substrate. It seems that the above phenomena cause the defects of the final polymer pattern. To reduce the defect, it is important to check the initial resin thickness.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.20 no.4
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• pp.472-477
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• 2011

This paper shows the method of fabrication of a micro lens array comprised of a Nipkow disk used in a large-area, high-speed confocal microscopy. A Nipkow disk has two components, a micro lens array disk and a pinhole array disk. The microlens array focuses illumination light onto the pinhole array disk and redirects reflected light from a surface to a sensor. The micro lens which are positioned in order on a disk have a hemispheric shape with a few tens of micron in diameter, and can be fabricated by a variety of methods like mechanical machining, semiconductor process, replication process like imprinting process. This paper shows how to fabricate the micro lens array which has a long focal length by reflow and imprinting process.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.19 no.8
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• pp.838-842
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• 2009

Vibrational analysis is presented for a visual alignment system of nano-imprint process in this study. For a nano-imprinting equipment, the visual alignment system is one of the essential parts in order to align the mold into the target panel. For the precision alignment, the vibration from inside and outside of the vision system should be avoided, and the elimination of the vibration should be considered in the design process of the visual alignment design. In this work, vibrational characteristics for the vision system frame is analyzed and topology optimization of a frame section area is carried out. With the results of the analysis, a new frame design are suggested. Design consideration for constructing a visual alignment system in view of optimal design is also discussed.

• Proceedings of the KSME Conference
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• 2007.05a
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• pp.502-505
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• 2007

PMMA has been extensively adopted in Nano Imprint Lithography(NIL). PMMA nano-structures experience severe mechanical load and deformation during NIL process, and understanding its mechanical behavior is very important in designing and optimizing NIL process. One of the most promising techniques for characterizing the mechanical behavior of nano structures is nano pillar compression test. In this study, the mechanical behaviors of PMMA pillars during compression test are analyzed using Molecular Dynamics. Two methods for simulation of PMMA nano pillars are proposed. The stress-strain relationship of nano-scale PMMA structure is obtained based on CVFF(Covalent Valence Force Fields) potential and the dependency of the applied strain rate on the stress-strain relationship is analyzed. The obtained stress-strain relationships can be useful in simulating nano-scale PMMA structures using Finite Element Method(FEM) and understanding the experimental results obtained by compression test of PMMA nano pillars.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2003.06a
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• pp.196-198
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• 2003

Classical lithography in semiconductor employs stepper technologies. Limits of this technology are clearly seen at structures below 100nm. Nano-imprinting lithography is a new method for generating patterns in submicron range at reasonable cost. In order to manufacture nano-imprinting lithography(NIL) equipment, several NIL manufacturers have been developing key technologies for realization of nano-imprinting process, recently. In this paper, we've been describe state-of-the-art and technology trends for nano-imprinting lithography equipments.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.55 no.5
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• pp.267-271
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• 2006

A polymeric waveguide-type wavelength filter based on a Bragg grating has been proposed and fabricated using the simple nanoimpring technique, for the first time to our knowledge. An ultraviolet transparent stamp with the single-mode waveguide pattern incorporating a surface-relief-type Bragg grating was specially designed selective dry-etching process. Using this stamp, the device fabrication was substantially involving just a single-step process of imprint followed by polymer spin-coating. The achieved maximum reflection was higher than 25 dB at the center wavelength of 1569 nm. And the 3-dB bandwidth was 0.8 nm for the device length of 1.5 cm.

• Proceedings of the KIEE Conference
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• 2006.10a
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• pp.101-102
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• 2006

PZT thin films, which are the representative ferroelectric materials in ferroelectric random access memory (FRAM), have some serious problem such as the imprint, retention and fatigue which ferroelectric properties are degraded by repetitive polarization. BL T thin film capacitors were fabricated by plasma etching, however, the plasma etching of BLT thin film was known to be very difficult. In our previous study, the ferroelectric materials such as PZT and BLT were patterned by chemical mechanical polishing (CMP) using damascene process to top electrode/ferroelectric material/bottom electrode. It is also possible to pattern the BLT thin film capacitors by CMP, however, the CMP damage was not considered in the experiments. The properties of BLT thin films were changed by the change of polishing pressure although the removal rate was directly proportional to the polishing pressure in CMP process.