• Laser Solutions
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• v.16 no.4
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• pp.1-6
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• 2013

Femtosecond laser patterning of ITO on a touch screen panel with a shaped fs laser beam was investigated. A quasi flat-top beam was formed using a variable mask and a planoconvex lens. The spatial profile of the original Gaussian beam and the shaped beam were monitored by a CCD beam profiler. The laser patterned ITO film was examined using an optical microscope, Scanning Electron Microscope (SEM) with Energy Dispersive X-ray Spectroscopy (EDS), and Atomic Force Microscope (AFM). It turned out that the quality of the ITO pattern fabricated by a shaped beam is superior to that of the pattern without beam shaping in terms of debris generation, height of the craters, and homogeneity of the bottom. Optimum processing window was determined at the laser irradiance exhibiting 100% removal of Sn. The removal rate of In was measured to be 83%.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.28 no.9
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• pp.1270-1275
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• 2004

Standard positive photoresist techniques were adapted to generate nano-scale patterns of gold substrate using self-assembled monolayers (SAMs) and femtosecond laser. SAMs formed by the adsorption of alkanethiols onto gold substrate are employed as very thin photoresists, Alkanethiolates formed by the adsorption of alkanethiols are oxidized on exposure to UV light in the presence of air to alkylsulfonates. Specifically, it is known that deep UV light of wavelength less than 200nm is necessary for oxidation to occur. In this study, ultrafast laser of wavelength 800nm and pulse width 200fs is applied for photolithography. Results show that ultrafast laser of visible range wavelength can replace deep UV laser source for photo patterning using thin organic films. Femtosecond laser coupled near-field scanning optical microscopy facilitates not only the patterning of surface chemical structure, but also the creation of three-dimensional nano-scale structures by combination with suitable etching methods.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.15 no.4
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• pp.46-50
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• 2016

A laser head was designed for micro-scale patterning and joining applications. The target feature size of the pattern was $100{\mu}m$, and optics were designed to perform the target. Two singlet lenses were combined to minimize the chromatic aberration, and the geometry of the lenses was calculated by using the raytracing method with a commercial software program. As a restriction of lens design, the focal length was set at 100mm, and the maximum diameter of the lens or beam size was limited to 10mm for the assembly in the limited cage size. The maximum temperatures were calculated to be $1367^{\circ}C$, $1508^{\circ}C$, and $1905^{\circ}C$ for 10, 12, and 15 Watts of power, respectively. A specially designed laser head was used to compensate for the distance between the object and the lens. The detailed design mechanism and 3D data were presented. The optics design and detailed performance of the lens were analyzed by using MTF and spot diagram calculation.

• Journal of the Microelectronics and Packaging Society
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• v.27 no.3
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• pp.73-76
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• 2020

Silver nanowires (AgNWs) intrinsically possess high conductivity, ductility, and network structure percolated in a low density, which have led to many advanced applications of transparent and flexible electronics. Most of these applications require patterning of AgNWs, for which photolithographic and printing-based techniques have been widely used. However, several drawbacks such as high cost and complexity of the process disturb its practical application with patterning AgNWs. Herein, we propose a novel method for the patterning of AgNWs by employing UV-curable adhesive tape with a structure of liner/adhesive layer/polyolefin (PO) film and UV irradiation to simplify the process. First, the UV-curable adhesive tape was attached to AgNWs/polyurethane (PU), and then selectively exposed to UV irradiation by using a photomask. Subsequently, the UV-curable adhesive tape was peeled off and consequently AgNWs were patterned on PU substrate. This facile method is expected to be applicable to the fabrication of a variety of low-cost, shape-deformable transparent and wearable devices.

• Proceedings of the Korean Vacuum Society Conference
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• 2016.02a
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• pp.271-271
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• 2016

highly doped N-type 실리콘 기판 위에 극초단 펄스 레이저를 이용하여 LIPSS (Laser-Induced Periodic Surface Structure) 패턴을 형성하였다. 형성된 LIPSS 구조는 $15{\mu}m$와 500 nm 주기를 가지는 ripple로 형성이 되었고 이 구조를 형성하기 위해서 사용된 레이저는 Satsuma HP2, Amplitude syst?mes 이다. LIPSS 패턴을 가지는 기판 위에는 유기반도체 물질인 pentacene을 50 nm로 열 증착방법을 통해 박막을 형성하여 유기박막트랜지스터를 제작하였고, hole mobility를 측정하였다. LIPSS 패턴을 가지는 실리콘 기판과 pristine 실리콘 기판 위의 pentacene의 morphology를 AFM으로 관찰하고 유도된 구조를 연구하였다.

• Proceedings of the Korean Society of Laser Processing Conference
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• 2006.06a
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• pp.123-128
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• 2006

We constructed a micro-patterning system that build patterns on a photoresist coated wafer using laser direct writing system. Confocal microscope system was adapted for real-time auto-focusing of the laser writing lens to generate lines of uniform width.

• Laser Solutions
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• v.8 no.1
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• pp.39-44
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• 2005

We report experimental results on the periodic patterning using a Ti:sapphire femtosecond laser (800nm, 100fs, 1kHz). Periodic structures with reproducible basic patterns are produced both on the surface and inside transparent materials. Period patterning for the application to display panel is widely investigated. Also, the submicron dot and line patterns are fabricated inside fused silica glass, which is important for the formation of diffraction grating in integrated optical circuit. finally, we demonstrate the utility of the femtosecond laser application to optical memory by fabricating the three-dimensional dot patterns.

• Laser Solutions
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• v.13 no.2
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• pp.6-9
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• 2010

In printed electronics, printing rolls are used to transfer electronic ink onto a flexible substrate. Generally printing rolls are being made by the indirect laser method which is based on the etch process, thus not environment-friendly and not suitable for making a large printing roll. For the pursuit of making a large printing roll for mass printing of electronic devices, we have directly engraved micro-patterns into a Zn plated printing roll using a 30W pulse-modulated fiber laser. We have successfully engraved line patterns ranging from about 15-30${\mu}m$ in width.

• Laser Solutions
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• v.9 no.1
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• pp.17-23
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• 2006

The technologies of laser micromachining are changed toward more complex-micropatterning, from the micro circle-shaped hole drilling to the micro arbitrary-shaped hole drilling. In this paper, the fundamental experiments by using DPSS 3rd harmonic $Nd:YVO_4\;laser({\lambda}=355nm)$ were carried out in order to obtain the feasibility of flexible micropatterning by various fixed masks. Fixed masks and Galvano scanners were investigatde to make micro patterns. from these experimental results, micropatterns on PEN film were rapidly manufactured in large area.

• 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.