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

• The Magazine of Kiice
• /
• v.9 no.1
• /
• pp.37-43
• /
• 2008

• 전기의세계
• /
• v.56 no.10
• /
• pp.34-38
• /
• 2007

• Polymer Science and Technology
• /
• v.20 no.1
• /
• pp.40-45
• /
• 2009

• Proceedings of the KSME Conference
• /
• 2004.11a
• /
• pp.410-415
• /
• 2004

Molecular dynamics simulations of nanoimprint lithography in which a stamp with patterns is pressed onto amorphous poly-(methylmethacrylate) (PMMA) surface are performed to study the deformation of polymer. Force fields including bond, angle, torsion, inversion, van der Waals and electrostatic potential are used to describe the intermolecular and intramolecular force of PMMA molecules and stamp. Periodic boundary condition is used in horizontal direction and $Nos\acute{e}$-Hoover thermostat is used to control the system temperature. As the simulation results, the adhesion forces between stamp and polymer are calculated and the mechanism of deformation are investigated. The effects of the adhesion force and friction force on the polymer deformation are also studied to analyze the pattern transfer in nanoimprint lithography. The mechanism of polymer deformation is investigated by means of inspecting the indentation process, molecular configurational properties, and molecular configurational energies.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2004.10a
• /
• pp.1119-1122
• /
• 2004

In the UV-NIL process using an elementwise patterned stamp (EPS), which includes channels formed to separate each element with patterns, low-viscosity resin droplets with a nano-liter volume are dispensed on all elements of the EPS. Following pressing of the EPS, the EPS is illuminated with UV light to cure the resin; and then the EPS is separated from several thin patterned elements on a wafer. Experiments on UV-NIL were performed on an EVG620-NIL. 50 － 70 nm features of the EPS were successfully transferred to 4 in. wafers. Especially, the wafer deformation during imprint was analyzed using the finite element method (FEM) in order to study the effect of the wafer deformation on the UV-NIL using EPS.

• Proceedings of the KSME Conference
• /
• 2007.05a
• /
• pp.343-348
• /
• 2007

Molecular dynamics study of thermal NIL (Nano Imprint Lithography) process is performed to examine stamp-resist interactions. A layered structure consists of Ni stamp, poly-(methylmethacrylate) thin film resist and Si substrate was constructed for isothermal ensemble simulations. Imposing confined periodicity to the layered unit-cell, sequential movement of stamp followed by NVT simulation was implemented in accordance with the real NIL process. Both vdW and electrostatic potentials were considered in all non-bond interactions and resultant interaction energy between stamp and PMMA resist was monitored during stamping and releasing procedures. As a result, the stamp-resist interaction energy shows repulsive and adhesive characteristics in indentation and release respectively and irregular atomic concentration near the patterned layer were observed. Also, the spring back and rearrangement of PMMA molecules were analyzed in releasing process.

• Proceedings of the KSME Conference
• /
• 2007.05a
• /
• pp.332-336
• /
• 2007

Temperature is an essential process variable in nanoimprint lithography(NIL) where the temperature varies between room temperature and above the glass transition temperature. To simulate NIL process, we employ both the Nose-Poincare method for temperature controlled molecular dynamics(MD) and force field for polymer material i.e. polymethyl methacrylate(PMMA), which is most widely selected as NIL resist. Nose-Poincare method, which convinces the conservation of Hamiltonian structure and time-reversal symmetry, overcomes the drawbacks inherent in the conventional methods such as Nose thermostat and Nose-Hoover thermostat. Thus, this method exhibits enhanced numerical stability even when the temperature fluctuation is large. To describe PMMA, we adopt the force field which account for bond stretch, bending, torsion, inversion, partial charge, and van der Waals energy.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
• /
• 2004.11a
• /
• pp.83-89
• /
• 2004

In this paper, molecular dynamics simulations are performed to analyze the adhesion between a diamond mould and a copper substrate in diamond nanoimprint lithography. The diamond nanoimprint lithography process is simplified as punch-type nanoindentation. The copper substrates are assumed to monocrystalline and defect free and consist of $22500\~80000$ atoms depending on their dimension. The diamond moulds consist of 916 or 2414 atoms, which is assumed to be rigid. The consistent results lot the maximum normal force and the adhesion force are obtained regardless of the size of substrates and the adhesion hysteresis is shown in all cases. It is found that the friction acting on the sidewalls of the mould affects the adhesion significantly when the mould is released from the substrate.

• Proceedings of the KSME Conference
• /
• 2003.04a
• /
• pp.1069-1072
• /
• 2003

Ultraviolet-nanoimprint lithography (UV-NIL) is a promising nanoimprint method for cost-effectively defining nanometer scale structures at room temperature and low pressure. Nanostamp fabrication technology is a key technology for UV-NIL because fabricating a high resolution nanostamp is the first step for defining high resolution nanostructures in a substrate. We used quartz as an UV transparent stamp material for the UVNIL. A $5{\times}5{\times}0.09$ inch stamp was fabricated using the quartz etch process in which Cr film was used as a hard mask for transferring nanostructures into the quartz. In this paper, we describe the quartz etching process and discuss the results including SEM images.