• Proceedings of the KIEE Conference
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• 2004.07c
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• pp.1573-1575
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• 2004

An alumina membrane with nano-sized pores was fabricated by anodic oxidation. The shape and structure of the pore on alumina membrane were changed according to the roughness of aluminum surface. The shape and structure of the nano-sized pre were investigated according to purity of aluminum substrate for the anodization process. The aluminum substrates with 99.5% and 99.999% purities were used. The aluminum substrate(99.5%) was anodized after the processes of pressing, mechanical polishing, chemical polishing, and electrochemical polishing. The nano-sized pores with the pore size of 50 - 100nm, the cell size of 20-50nm and the thickness of $10{\mu}m{\sim}45{\mu}m$ were obtained. Even though the electrochemical polishing was used for the aluminum substrate (99.999%), the same characteristics as the aluminum substrate (99.5%) was obtained. The alumina membrane prepared by anodization for 5 min using fixed voltage method shows the pore with irregular shape. The pore shape was changed to regular shape after pore widening process.

• Journal of the Korean Vacuum Society
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• v.10 no.3
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• pp.361-367
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• 2001

Recently, Chemical Mechanical Polishing(CMP) has become a leading planarization technique as a method for silicon wafer planarization that can meet the more stringent lithographic requirement of planarity for the future submicron device manufacturing. The SOI(Silicon On Insulator) wafer has received considerable attention as bulk-alternative wafer to improve the performance of semiconductor devices. In this paper, the objective of study is to investigate Material Removal Rate(MRR) and surface micro-roughness effects of slurry and pad in the CMP process. When particle size of slurry is increased, Material Removal rate increase. Surface micro-roughness is greater influenced by pad than by particle size of slurry. As a result of AM measurement, surface micro-roughness was improved from 27 $\AA$ Rms to 0.64 $\AA$Rms.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.11 no.5
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• pp.218-223
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• 2001

The chemical-mechanical polishing process was carried out for 2"-dia. sapphire wafer grown by horizontalBridgman method on the urethane lapping pad with the silica sol. The polished wafer shows the full-width at halfmaximum of 200~400 arcsec in double-crystal X-ray diffraction, indicating that the slicing, grinding and lapping processes before the polishing process affected the crystalline structural property of the wafer surface by the mechanical residual stress. For the inclusion of surface treatments after chemical-mechanical polishing such as the thermal annealing at the temperature of $1,200^{\circ}C$for 4 hrs. and chemical etching, the crystalline quality was sigdicantly enhanced with the reduced full-width at half maximum up to 8.3 arcsec.arcsec.

• Journal of the Optical Society of Korea
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• v.15 no.4
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• pp.394-397
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• 2011

For the purpose of fabricating off-axis aspheric optics, we propose an 8-axis-polishing machine combined with a testing tower whose height is up to 9 m. The proposed polishing machine was designed and analyzed by using a well-known finite element method. The eight axes of the machine have a synchronized motion generated by a computer, and each axis was calibrated by a heterodyne laser interferometer or an optical encoder. After calibration, the maximum positioning error of the machine was less than 2 ${\mu}m$ within a whole 2 m ${\times}$ 2 m area. A typical fabrication result of a ${\phi}1.5$ m concave mirror was also described in this manuscript.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.10 no.6
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• pp.146-151
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• 2011

Wax spin coating is a part of several wafer handling processes in the silicon wafer polishing station. It is important to ensure the wax layer free of contamination to achieve the high degree of planarization on wafers after wafer polishing. Three-dimensional air flow characteristics in a wax spin coater are numerically investigated using computational fluid dynamics techniques. When the bottom of the wax spin coater is closed, there exists a significant recirculation zone over the rotating ceramic block. This recirculation zone can be the source of wax layer contamination at any rotational speed and should be avoided to maintain high wafer polishing quality. Thus, four air suction ducts are installed at the bottom of the wax spin coater in order to control the air flow pattern over the ceramic block. Present computational results show that the air suction from the bottom is quite an effective method to remove or minimize the recirculation zone over the ceramic block and the wax coating layer.

• Design & Manufacturing
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• v.11 no.3
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• pp.51-55
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• 2017

Micro fuel cells have high reliability and long usage time. Among them, PEMFC (polymer Electrolyte Membrane Fuel Cell) is suitable as a portable power source because it is easy to fix electrolyte and simple structure. The bipolar plate, a key component of the fuel cell, is produced by cutting. In the case of micro fuel cell separator, burr is very small and the flow channel size in the separator is very small. Therefore, it is difficult to remove burrs in the usual way such as a brushing or ultra-sonic method. Therefore, this study proposed electrolytic polishing process and analyzed the characteristics of each condition by introducing the concept of roughness reduction rate. In addition, the ultrasonic process was added to analyze the effect of ultrasonic addition.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.11a
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• pp.140-143
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• 2003

BST thin films have a good thermal-chemical stability, insulating effect and variety of phases. However, BST thin films have problems of the aging effect and mismatch between the BST thin film and electrode. Also, due to the high defect density and surface roughness at grain boundarys and in the grains, which degrades the device performances. In order to overcome these weakness, we first applied the chemical mechanical polishing (CMP) process to the polishing of ferroelectric film in order to obtain a good planarity of electrode/ferroelectric film interface. BST ferroelectric film was fabricated by the sol-gel method. And then, we compared the structural characteristics before and after CMP process of BST films. We expect that our results will be useful promise of global planarization for FRAM application in the near future.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2004.10a
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• pp.92-96
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• 2004

In this paper, polishing method using bonded magnetic abrasive particle has been applied to the micro mold polishing. Through process control using the Run-to-Run control, it tried to form the surface roughness In order to grasp the influence of the surface roughness which is reached by selection of control factor and the factor, a design of experiment was been processed. The study is processed with a purpose of to embody and to maintain the surface roughness of nano scale by the basis of an influence between a control factor and the factors which has been selected in this way. As a result, the result of the process control converged at a target value of surface roughness Ra 10nm and Rmax 50nm

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1997.04a
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• pp.1009-1014
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• 1997

The small material removal rate of elastic emission machinong (EEM) becomes a serious problem due to using fine powder particles for obtaining finished of high quality. If a cylindrical polyurethane-wheel is used as a tool for accelerating powder particles, the efficiency of machining may be increased through enlarging the machining regionand increasing the surface velocity of the wheel. If these analyicl results are compared with experimental ones, characteristics of EEM using polyurethan-wheel can be clarified. In this study, effects of EEM using cylindrical polyurethane-wheel on the surface roughness and the material removal rate were verified through polishing of the brittle material under various conditions. The high-efficient polishing of silicon wafer has been also carried out using this method.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2003.06a
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• pp.557-560
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• 2003

Magnetorheological finishing(MRF) is a newly developed and recently commercialized for finishing optical components. The magnetorheological fluid consists of a water based suspension of carbonyl iron, nonmagnetic polishing abrasives, and small amounts of stabilizer. This magnetorheological fluid is pumped from conditioner on the rotating wheel and suctioned back to the conditioner, where it cooled to setpoint temperature and evaporative losses are replaced. This method could produce some problems in suction. So newly designed MRF tools is proposed in which MR fluid is not circulated and conditioned by the slurry. The new polishing mechanism is experimented. Measured surface roughness supports the validity of this mechanism.