• Proceedings of the Korean Society of Precision Engineering Conference
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• 2010.05a
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• pp.197-198
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• 2010

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2011.06a
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• pp.1507-1508
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• 2011

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2004.10a
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• pp.36-39
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• 2004

Glass molding is an advantageous method to manufacture glass micro optical components. However, it is difficult to make Tungsten Carbide core for glass microlens array. We have developed novel method to fabricate Tungsten Carbide core for micro glass components using pressure forming. Silicon masters were fabricated by micro machining. Tungsten Carbide core was fabricated by pressure forming and sintering. And we made high quality surface of Tungsten Carbide core by using the magnetic-field-assisted polishing process.

• Journal of the Korean Society for Precision Engineering
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• v.11 no.1
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• pp.177-183
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• 1994

The ball-end milling process is widely used in the die/mold industries, and it is very suitable for the machining of free-from surfaces. However, cusps(or scallops) remaining at the machined part along the cutter paths require anothe finish process such as polishing or grinding. In this study, a high sped micro ball-end milling method has been suggested for the finish of free- form surfaces. A new tool path which makes the geometrical roughness of workpiece be constant through the machined surface has been developed. In the high speed machining of micro ball-end muling experimets, the developed tool paths have been successfully applied. And it was concluded that the surface roughness from this finish cuts of micro ball-end milling process was acceptable.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.18 no.9
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• pp.803-809
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• 2005

Cerium ammonium nitrate (CAN) and nitric acid was used an etchant and an additive for Ru etching and polishing. pH and Eh values of the CAN and nitric acid added chemical solution satisfied the Ru etching condition. The etch rate increased linearly as the concentration of CAN increased. Nitric acid added solution had the high etch rate. But micro roughness of etched surfaces was not changed before and after etching, The removal rate of Ru film was the highest in $1wt\%$ abrasive added slurry, and not increased despite the concentration of alumina abrasive increased to $5wt\%$. Even Ru film was polished by only CAN solution due to the friction. The highest removal rate of 120nm/min was obtained in 1 M nitric acid and $1wt\%$ alumina abrasive particles added slurry. The lowest micro roughness value was observed in this slurry after polishing. From the XPS analysis of etched Ru surface, oxide layer was founded on the etched Ru surface. Therefore, Ru was polished by chemical etching of CAN solution and oxide layer abrasion by abrasive particles. From the result of removal rate without abrasive particle, the etching of CAN solution is more dominant to the Ru CMP.

• Tribology and Lubricants
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• v.35 no.5
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• pp.274-285
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• 2019

Chemical mechanical polishing (CMP), which is a material removal process involving chemical surface reactions and mechanical abrasive action, is an essential manufacturing process for obtaining high-quality semiconductor surfaces with ultrahigh precision features. Recent rapid growth in the industries of digital devices and semiconductors has accelerated the demands for processing of various substrate and film materials. In addition, to solve many issues and challenges related to high integration such as micro-defects, non-uniformity, and post-process cleaning, it has become increasingly necessary to approach and understand the processing mechanisms for various substrate materials and abrasive particle behaviors from a tribological point of view. Based on these backgrounds, we review recent CMP R&D trends in this study. We examine experimental and analytical studies with a focus on substrate materials and abrasive particles. For the reduction of micro-scratch generation, understanding the correlation between friction and the generation mechanism by abrasive particle behaviors is critical. Furthermore, the contact stiffness at the wafer-particle (slurry)-pad interface should be carefully considered. Regarding substrate materials, recent research trends and technologies have been introduced that focus on sapphire (${\alpha}$-alumina, $Al_2O_3$), silicon carbide (SiC), and gallium nitride (GaN), which are used for organic light emitting devices. High-speed processing technology that does not generate surface defects should be developed for low-cost production of various substrates. For this purpose, effective methods for reducing and removing surface residues and deformed layers should be explored through tribological approaches. Finally, we present future challenges and issues related to the CMP process from a tribological perspective.

• Restorative Dentistry and Endodontics
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• v.18 no.2
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• pp.447-462
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• 1993

To evaluate the marginal leakage in Class V cavity this study has been undertaken to compare the sandwich technique with the conventional method, and find out the effect of lining material, lining method, and polishing time on sandwich technique. Ninty extracted teeth were divided into eight test groups and a control group, and were prepared with a buccal Class V cavity. Four test groups were lined with Dentin Cement whereas the other four test groups were lined with Vitrabond. Half of the either group were lined 0.5mm short of the carvosurface margin and the rest were lined completely to the carvosurface margin. The four subgroups were further divided into specimens which were polished immediately and 24 hours after resin filling. The polished specimens were immersed in $37^{\circ}C$, 0.5% methylene blue solution for 24 hous after thermocycling at $5^{\circ}C$ and $55^{\circ}C$, 200 times and buccolingually sectioned. The sectioned specimens were examined dye penetration under the light microscope. The following results were obtained, 1. At the enamel margin, the conventional method showed a lower microleakage than the sandwich technique. The difference between the control and Vitrabond group was statistically significant(P<0.05), but no difference between the control and Dentin Cement group, and between the lining materials was observed. 2. At the dentinal margin, the sandwich technique showed a significant lower amount of microleakage (P<0.05), but there was no significant difference between the lining materials. 3. Regardless of the lining material, lining method, and polishing time used, values of microleakage were significantly higher at the dentinal margin compared to the enamel margin(P<0.05). 4. In specimens till the cavosurface margin, microleakage at the dentinal margin was less with the light-cured base than with the chemically-cured base, but there was no siginificantly difference between the lining materials regarding the lining method and polishing time. 5. The lining material, lining method, and polishing time did not affect the amount of micro leakage in the sandwich technique(P<0.05).

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.07a
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• pp.370-373
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• 2003

As the integrated circuit device shrinks to the smaller dimension, the chemical mechanical polishing (CMP) process was required for the global planarization of inter-metal dielectric(IMD) layer with free-defect. However, as the IMD layer gets thinner, micro-scratches are becoming as major defects. Chemical-Mechanical Planarization(CMP) of conductors is a key process in Damascene patterning of advanced interconnect structure. The effect of alternative commerical slurries pads, and post-CMP cleaning alternatives are discuess, with removal rate, scratch dentisty, surface roughness, dishing, erosion and particulate density used as performance metrics. Electroplated copper depostion is a mature process from a historical point of view, but a very young process from a CMP persperspective. While copper electrodepostion has been used and stuidied for dacades, its application to Cu damascene wafer processing is only now ganing complete accptance in the semiconductor industry. The polishing mechanism of Cu CMP process has been reported as the repeated process of passive layer formation by oxidizer and abrasion action by slurry abrasives. however it is important to understand the effect of oxidizer on copper pasivation layer in order to obtain higher removal rate and non-uniformity during Cu-CMP process. In this paper, we investigated the effects of oxidizer on Cu-CMP process regarding the additional volume of oxidizer.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.06a
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• pp.1294-1298
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• 2005

In this study, combined micro press and surface finishing process are proposed to fabricate the micro nozzle array on a stainless steel sheet metal. In micro hole punching process the burr occurs inevitably, but the burr must be minimized in order to improve the quality and accuracy of the product. For this reason, subsequent magnetic field-assisted finishing technique is applied to remove the burr which exists around the nozzles for ink-jet printer head and proved to be a feasible for deburring by experiment. The deburring characteristics of sheet metals were investigated changing with polishing time and magnetic abrasive size. After the deburring, the burr size has remarkably reduced and roundness of the hole also has improved.

• Journal of the Korean Society for Precision Engineering
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• v.33 no.11
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• pp.905-910
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• 2016

Infrared (IR) optic lens can be fabricated by a single point diamond turning (SPDT) machine without subsequent polishing process. However, this machining process often leaves micro-cracks that deteriorate the surface quality. In this work, we propose an experimental design to remove micro-cracks on IR lens. The proposed design gathered data between cutting process condition and Rt surface roughness. This is of great importance because the scale of micro-cracks is a few micrometer. Rt surface roughness is suitable for analyzing maximum peak height signals of the profile. The experimental results indicate that feed per revolution variable is one of the most dominant variable, affecting the generation micro-cracks on IR lens surfaces.