• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2004.05a
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• pp.259-264
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• 2004

The hot embossing process as a method for the fabrication of polymer is becoming increasingly important because of its simple process, low cost, high replication fidelity and relatively high throughput. In this paper, we carried out experimental studies and numerical simulations in order to understand the viscous flow of polymer film during hot embossing process. As the initial step of quantitating the hot embossing process, simple parametric studies for the embossing conditions have been carried out using high resolution masters which patterned by DRIE process. Under different embossing times and pressures, the viscous flow of PMMA films into micro/nano cavities has been investigated. Also, the viscous flow during the hot embossing process has been simulated by the continuum based FDM analysis considering micro/nano effect, such as surface tension and contact angle.

• Journal of the Korean Society for Precision Engineering
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• v.22 no.8 s.173
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• pp.159-164
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• 2005

The Hot Embossing Lithography(HEL) as a method fur the fabrication of the nanostructure with polymer is becoming increasingly important because of its simple process, low cost, high replication fidelity and relatively high throughput. In this paper, we carried out experimental studies and numerical simulations in order to understand the viscous flow of the polymer (PMMA) film during the hot embossing process. To grasp the characteristics of the micro patterning rheology by process parameters (embossing temperature, pressure and time), we have carried out various experiments by using the nickel-coated master fabricated by the deep RIE process and the plasma sputtering. During the hot embossing process, we have observed the characteristics of the viscoelastic behavior of polymer. Also, the viscous flow during the hot embossing process has been simulated by the continuum based FDM(Finite Difference Method) analysis considering the micro effect, such as a surface tension and a contact angle.

• 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.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.16 no.6
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• pp.168-174
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• 2007

A ceramic glass mold was developed for micro hot-embossing and replicated polymer parts are fabricated. The glass-ceramic micro mold could be fabricated with a laser process and a wet etching process and the fabrication time could be saved a lot. Various polymer micro structures can be obtained by hot-embossing. The process parameters such as ho-embossing temperatures or pressures were investigated and optimized. This process can be applied for fabrication of micro structures for flip-chips or micro fluidic channels for bio-engineering. The advantages and disadvantages of this process are discussed, too.

• Korean Journal of Materials Research
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• v.15 no.9
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• pp.589-593
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• 2005

Nanoimprinting lithography (NIL) is known as a suitable technique for fabricating nano and micro structures of high definition. Hot embossing is one of NIL techniques and can imprint on thin films and bulk polymers. Key issues of hot embossing are time and expense needed to produce a stamp withstanding a high temperature and pressure. Fabrication of a metal stamp such as an electroplated nickel is cost intensive and time consuming. A ceramic stamp made by silicon is easy to break when the pressure is applied. In this paper, a plastic stamp using a high temperature epoxy was fabricated and tested. The plastic stamp was relatively inexpensive, rapid to produce and durable enough to withstanding multiple hot embossing cycles. The merits of low viscosity epoxy solutions were a fast degassing and a rapid filling the microstructures. The hot embossing process with plastic stamp was performed on PMMA substrates. The hot embossing was conducted at 12.6 bar, $120^{\circ}C$ and 10 minutes. An imprinted PMMA wafer was almost same value of the plastic stamp after 10 times embossing. Entire fabrication process from silicon master to plastic stamp was completed within 12 hours.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.06a
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• pp.1140-1144
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• 2005

A plastic-based CE (capillary electrophoresis) microchip was fabricated by hot embossing process. A Si mold was made by wet etching process and a PMMA wafer was cut off from 1mm thick PMMA sheet. A micro-channel structure on PMMA substrate was produced by hot embossing process using the Si mold and the PMMA wafer. A vacuum assisted thermal bonding procedure was employed to seal an imprinted PMMA wafer and a blank PMMA wafer. The results of microscopic cross sectional images showed dimensions of channels were well preserved during thermal bonding process. In our procedure, the deformation amount of bonding process was below 1%. The entire fabrication process may be very useful for plastic based microchip systems.

• Macromolecular Research
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• v.12 no.5
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• pp.474-477
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• 2004

We present simple, low-cost methods for the fabrication of polymeric waveguides that have large core sizes for use as optical interconnects. We have used both hot embossing and micro-contact printing techniques for the fabrication of multimode waveguides using the same materials. Rectangular and large-core (60${\times}$60 $\mu\textrm{m}$$^2$) channels were readily prepared when using these methods. The dimensions of the embossed and printed channels were the same as those of the pattern on the original master. The polymeric waveguides that we fabricated with large core sizes exhibited a low propagation loss of 0.1 dB/cm at 850 nm, which indicates that hot embossing and micro-contact printing are suitable techniques for the fabrication of optical waveguides having large-core.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2007.06a
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• pp.759-760
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• 2007

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2009.06a
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• pp.911-912
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• 2009

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2008.06a
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• pp.627-628
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• 2008