• Laser Solutions
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• v.15 no.3
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• pp.7-10
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• 2012

Dimensions (line/space) of circuits in IC substrates for high-end chips (e.g. CPU, etc.) are anticipated to decrease as small as $10{\mu}m/10{\mu}m$ in 2014. Since current etch-based circuit-patterning processes are not able to address the urgent requirement from industry, laser-based circuit patterning processes are under active research in which UV laser is used to engrave embedded circuits patterns into IC substrates. In this paper, we used a nanosecond UV laser to directly fabricate embedded circuit patterns into IC substrates with/without ceramic powders. In experiments, we engraved embedded circuit patterns with dimensions (width/depth) of abut $10{\mu}m/10{\mu}m$ and $6{\mu}m/6{\mu}m$ into the IC substrates. Due to the recoil pressure occurring during ablation, the circuit patterning of the IC substrates with ceramic powders showed the higher ablation rate.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.45 no.11
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• pp.8-12
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• 2008

For the reduction of fabrication cost and process time of AC plasma display panel (PDP), indium tin oxide (ITO) layer was patterned as bus electrode using Nd:$YVO_4$ laser. In comparison with the chemically wet etched ITO patterns, laser ablated ITO patterns showed the formation of shoulders and ripple-like structures at the edge of the ITO lines. For the reduction of shoulders and ripple-like structures, pulse repetition rate and scan velocity of laser was changed. In addition, we analyzed a discharge characteristic of PDP test panel to observe how the shoulders and ripple-like structures influence on the PDP. Based on experimental results, the pattern etched at the 500 mm/s and 40 kHz was better than any other condition. From this experiment we could see the possibility of the laser direct patterning for the application to the patterning of ITO in AC-PDP.

• Journal of the Korean Society for Precision Engineering
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• v.27 no.10
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• pp.93-99
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• 2010

A nano-stereolithography is the direct patterning process with a nanoscale resolution using twophoton absorption induced by a femtosecond laser. However, in the majority of the works, the fabrication of 3D microstructures have been done only onto transparent glass due to the use of an oil immersion objective lens for achieving a high resolution. In this work, the coaxial illumination and the auto-focusing system are proposed for the direct patterning of nano-precision patterns on an opaque substrate such as a silicon wafer and a metal substrate. Through this work, 3D polymer structures and metallic patterns are fabricated on a silicon wafer using the developed process.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2001.04a
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• pp.844-847
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• 2001

The application of laser direct etching has been discussed, and believed that the process is a very powerful method for micro machining. This study is focused on the micro patterning technology using laser direct etching process with no chemical damage of the material surface. A new introduced concept of energy synergy effect for surface micro machining is the combination of chemically ion reaction and laser thermal process. The etchant can't etch the material in room temperature, and used Ar laser has not power enough to machine. But, the machining is occurred in local area of the material by the combined energy. Using this process, the material is especially prevented from chemical damage for electric property. We have tested this new concept, and achieved a line with $1{mu}m$ width. The Ar laser with 488nm wavelength was used. The material was Si(100) wafer, and etchant is KOH solution. The application and flexibility of this process is in great hopes for MEMS structures and fabrication of the micro electric device parts.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2002.05a
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• pp.503-507
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• 2002

Mask manufacturing is a high COC and COO process in developing of semiconductor devices, because of the mass production tool with high resolution. Direct writing has been thought to be one of the patterning method to cope with development or small-lot production of the device. This study focused on the development of the direct, mastless patterning process using stereolithography tool for the easy and convenient application to micro and miso scale products. Experiments are utilized by three dimensional CAD/CAM as a mask and photo-curable resin as a photo-resist in a conventional stereo-lithography apparatus. Results show that the resolution of the pattern was achieved about 300 micron because of complexity of SLA apparatus settings, inspite of 100 micro of inherent resolution. This paper concludes that photo resist and laser spot diameter should be adjusted to get finer patterns and the proposed method is significantly feasible to mastless and low cost patterning with micro and miso scale.

• Journal of the Korean Society for Precision Engineering
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• v.33 no.10
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• pp.845-850
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• 2016

A direct laser lithography system is widely used to fabricate various types of DOEs (Diffractive Optical Elements) including lenses made as CGH (Computer Generated Hologram). However, a parametric study that uniformly and precisely fabricates the diffractive patterns on a large area (up to $200mm{\times}200mm$) has not yet been reported. In this paper, four parameters (Focal Position Error, Intensity Variation of the Lithographic Beam, Patterning Speed, and Etching Time) were considered for stabilization of the direct laser lithography system, and the experimental results were presented.

• Laser Solutions
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• v.10 no.2
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• pp.17-24
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• 2007

We have studied a laser direct writing lithography(LDWL). This is more important to apply to micro patterning using UV laser. We demonstrate the possibility of LDWL and construct the fabrication system. We use Galvano scanner to process quickly micro patterns from computer data. And laser beam is focused with $F-{\theta}$ lens. AZ5214 and SU-8 photoresist are chosen as experimental materials and a kind of well-known positive and negative photoresist respectively. Laser ablation mechanism depends on the optical properties of polymer. In this paper, therefore we investigate the phenomenon of laser ablation according to the laser fluence variation and measure the shape profile of micro patterned holes. From these experimental results, we show that LDWL is very useful to process various micro patterns directly.

• Textile Coloration and Finishing
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• v.35 no.2
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• pp.121-127
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• 2023

In this study, a comprehensive investigation was conducted on the morphological and property changes of laser-induced nanocarbon (LINC) as a function of laser process parameters. LINC was formed on the surfaces of polyimide films with different backbone structures under various process conditions, including laser power, scan speed, and resolution. Three different forms of LINC electrodes (i.e., continuous 3D porous graphene, wooly nanocarbon fibers, line cut) were formed depending on the laser power and scan speed. Furthermore, heteroatom doping induced from the chemical structure of the polyimide during laser patterning was found to be effective in modifying the electrical properties of LINC electrodes. The LINC surfaces exhibited different microstructures depending on the laser beam resolution under constant laser power and scan speed, allowing for controllable surface wettability. The correlation between the chemical structure of the polymer substrate, laser process parameters, and carbonized surface properties in this study is expected to be utilized as fundamental understanding for the manufacturing of next-generation carbon-based electronic devices.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2012.10a
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• pp.319-320
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• 2012

• Transactions on Electrical and Electronic Materials
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• v.14 no.2
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• pp.59-62
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• 2013

At an infra-red (IR) wavelength of 1,064 nm, a diode-pumped Q-switched $Nd:YVO_4$ laser was used for the direct patterning of various transparent conductive oxide (TCO) thin films on glass substrate. With various laser beam conditions, the laser ablation results showed that the indium tin oxide (ITO) film was removed completely. In contrast, zinc oxide (ZnO) film was not etched for any laser beam conditions and indium gallium zinc oxide (IGZO) was only ablated with a low scanning speed. The difference in laser ablation is thought to be due to the crystal structures and the coefficient of thermal expansion (CTE) of ITO, IGZO, and ZnO. The width of the laser-patterned grooves was dependent on the film materials, the repetition rate, and the scanning speed of the laser beam.