• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.24 no.12
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• pp.982-987
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• 2011

In this study, $Ge_8Se_{(2+x)}Te_{(6-x)}$ thin film amorphous-to-crystalline phase-change rate was evaluated in using a nano-pulse scanner. The focused laser beam with a diameter <10 ${\mu}m$ was illuminated in the power (P) and pulse duration (t) ranges of 1-31 mW and 10-460 ns, respectively, with subsequent detection of the responsive signals reflected from the film surface. We also evaluated the material characteristics, such as optical absorption and energy gap, crystalline phases, and sheet resistance of as-deposited and annealed films. The result of experiments showed that the thermal stability of the Ge-Se-Te film is largely improved by adding Se.

• Applied Microscopy
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• v.41 no.2
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• pp.81-88
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• 2011

Even though importance of nano-scale structure and compositional analysis have been getting increased, existing analysis tools have been reached to their limitations. Recent development of Atom Probe Tomography (APT), providing 3-dimensional elemental distribution and compositional information with sub-nm scale special resolution and tens of ppm detection limit, is one of key technique which can overcome these limitations. However, due to the fact that APT is not well known yet in the domestic research area, it has been rarely utilized so far. Therefore, in this article, the theoretical background of APT was briefly introduced with sample preparation to help understanding APT analysis.

• Journal of the Korean Society for Precision Engineering
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• v.25 no.1
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• pp.138-144
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• 2008

Micro-machining of a brittle material such as glass, silicon, etc., is important in micro fabrication. Particularly, micro-abrasive jet machining (${\mu}-AJM$) has become a useful technique for micro-machining of such materials. The ${\mu}-AJM$ process is mainly based on the erosion of a mask which protects brittle substrate against high velocity of micro-particle. Therefore, fabrication of an adequate mask is very important. Generally, for the fabrication of a mask in the ${\mu}-AJM$ process, a photomask based on the semi-conductor fabrication process was used. In this research a rapid mask fabrication technology has been developed for the ${\mu}-AJM$. By scanning the focused UV laser beam, a micro-mask pattern was fabricated directly without photolithography process and photomask. Two kinds of mask patterns were fabricated using SU-8 and photopolymer (Watershed 11110). Using fabricated mask patterns, abrasive-jet machining of Si wafer were conducted successfully.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1999.05a
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• pp.617-620
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• 1999

In this study, the polarization e(fecal and the birefringence effect of amorphous germanium (a-Ge) thin films were investigated by using linearly polarized He-Ne laser beam. The a-7e thin films were deposited on the quarts substrate by plasma enhanced chemical vapor deposition (PECVD) and thermal vacuum evaporation In order to obtain the optimum grating arrays, inorganci resists such as Si$_3$N$_4$ and a-Se$_{75}$ Ge$_{25}$ , were prepared with the optimized thickness by Monte Carlo (MC) simulation. As the results of MC simulation, the thickness ofa-Se$_{75}$ Ge$_{25}$ resist was determined with Z$_{min}$ of 360$\AA$ . The resists were exposed to Ga$^{+}$-FIB with accelerating energies of 50 keV, developed by wet etching, and a-Ge thin film was etched by reactive ion-etching (RIE). Finally, we were obtained grating arrays which grating width and linewidth are 0.8${\mu}{\textrm}{m}$, respectively and we studied the polarization and birefringence effect in transmission grating array made of high refractive amorphous material, and the applicability as waveplates and polarizers in optical device.e.e.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.06a
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• pp.1155-1158
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• 2005

Micro-stereolithography is a newly proposed technology as a means that can fabricate a 3D micro structure of free form. It makes a 3D micro-structure by dividing the shape into many slices of relevant thickness along horizontal surfaces, hardening each layer of slice with a focused laser beam, and stacking them up to a desired shape. However, we do not anticipate the electric conductivity of the final product at the existing micro-stereolithography. The reason is that this technology uses polymer to make the product. Thus the new suspension which was mixed conventional photopolymer with metal powder was developed in this study. The developed suspensions were based on SL5180 which is commercialized resin and IMS03 that is made in our laboratory. And Triton X-100 was added at the suspension for getting the scattering effect and stabilizing effect. The layer recoating device was developed to be flat the mixed high viscosity suspension. A 3D micro structure was manufactured by using recoating system and micro-stereolithography system. The fabricated product was sintered to get the electric conductivity. After sintering, a pure copper product was made. In this study, new process was developed by making metal micro structure having an electric conductivity. This technology broadened the realm of the micro-stereolithography technology. And it will be applied to make the 3D micro structure of free form which has a high hardness and an electric conductivity in the near future.

• Journal of the Korean Society for Precision Engineering
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• v.26 no.7
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• pp.44-50
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• 2009

High-pressured jetting is now widely used in the advanced cutting processes of polymers, metals, glass, ceramics and composite materials because of some advantages such as heatless and non-contacting cutting. Similarly to the focused laser beam machining, it is well known as a type of high-density energy processes. High-pressured jetting is going to be developed not only to minimize the cutting line width but also to achieve the short cutting time as soon as possible. However, the interaction behavior between a work piece and high-velocity abrasive particles during the high-pressured jet cutting makes the impact mechanism even more complicated. Conventional high-pressured jetting is still difficult to apply to precision cutting of micro-scaled thin work piece such as thin metal sheets, thin ceramic substrates, thin glass plates and TMM (Thin multi-layered materials). In this paper, we proposed the advanced high-pressured jetting technology by introducing a new abrasives supplying method and investigated the optimal process conditions of the cutting pressure, the cutting velocity and SOD (Standoff distance).