• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.20 no.4
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• pp.303-307
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• 2007

This paper investigated the effect of the pad buffing process on the material removal characteristics and pad stabilization during silicon chemical mechanical polishing. The pads surface were controlled by the buffing process using a buffer made by the sandpaper. The buffing process is based on abrasive machining by using a high speed sandpaper. The controlled pad by the buffing process show less deformation deviation and stable material removal rate during the CMP process. In addition, the controlled pad ensure better uniformity of removal rate than comparative pads. As a result of monitoring, the controlled pad by the buffing process demonstrated constant and stable friction force signals from initial polishing stage. Therefore, the tufting process could control the pad surface to be uniform and improve the performance of the polishing pad.

• Tribology and Lubricants
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• v.23 no.6
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• pp.298-300
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• 2007

Frictional characteristics of mesoporous $SiO_2$ thin films were evaluated with different pore sizes. The films were manufactured by sol-gel and self-assembly methods to have a porous structure. The pores on the surface may play as the outlet of wear particle and the storage of lubricant so that the surface interactions could be improved. The pores were exposed on the surface by chemical mechanical polishing (CMP) or plasma-etching after forming the porous films. The ball-on-disk tests with mesoporous $SiO_2$ thin films on glass specimen were conducted at sliding speed of 15 rpm and a load of 0.26 N. The results show considerable dependency of friction on pore size of mesoporous $SiO_2$ thin films. The friction coefficient decreased as increasing the pore size. CMP process was very useful to expose the pores on the surface.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2006.11a
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• pp.380-381
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• 2006

Chemical mechanical polishing (CMP) technology has been widely used for global planarization of multi-level interconnection for ULSI applications. However, the cost of ownership and cost of consumables are relatively high because of expensive slurry. In this paper, we studied the mixed abrasive slurry (MAS). In order to save the costs of slurry, the original silica slurry was diluted by de-ionized water (DIW). And then, $ZrO_2$, $CeO_2$, and $MnO_2$ abrasives were added in the diluted slurry in order to promote the mechanical force of diluted slurry. We have also investigate the possibility of mixed abrasive slurry for the oxide CMP application.

• Korean Journal of Materials Research
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• v.26 no.9
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• pp.498-503
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• 2016

The characteristics of aqueous lithium recovery by ion exchange were studied using three commercial cation exchange resins: CMP28 (porous type strong acid exchange resin), SCR-B (gel type strong acid exchange resin) and WK60L (porous type weak acid exchange resin). CMP28 was the most effective material for aqueous lithium recovery; its performance was even enhanced by modifying the cation with $K^+$. A comparison to $Na^+$ and $H^+$ form resins demonstrated that the performance enhancement is reciprocally related to the electronegativity of the cation form. Further kinetic and equilibrium isotherm studies with the $K^+$ form CMP28 showed that aqueous lithium recovery by ion exchange was well fitted with the pseudo-second-order rate equation and the Langmuir isotherm. The maximum ion exchange capacity of aqueous lithium recovery was found to be 14.28 mg/g and the optimal pH was in the region of 4-10.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.55 no.6
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• pp.291-296
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• 2006

In this study, the sputtered BTO film was polished by CMP process with the self-developed $BaTiO_3$- and $TiO_2$-mixed abrasives slurries (MAS), respectively. The removal rate of BTO ($BaTiO_3$) thin film using the $BaTiO_3$-mixed abrasive slurry (BTO-MAS) was higher than that using the $TiO_2$-mixed abrasives slurry ($TiO_2$-MAS) in the same concentrations. The maximum removal rate of BTO thin film was 848 nm/min with an addition of $BaTiO_3$ abrasive at the concentration of 3 wt%. The sufficient within-wafer non-uniformity (WIWNU%) below 5% was obtained in each abrsive at all concentrations. The surface morphology of polished BTO thin film was investigated by atomic force microscopy (AFM).

• Journal of Powder Materials
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• v.25 no.5
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• pp.395-401
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• 2018

The improvement of dispersion stability for the primary polishing slurry in a CMP process is achieved to prevent defects produced by agglomeration of the slurry. The dispersion properties are analyzed according to the physical characteristics of each silica sol sample. Further, the difference in the dispersion stability is confirmed as the surfactant content. The dispersibility results measured by Zeta potential suggest that the dispersion properties depend on the content and size of the abrasive in the primary polishing slurry. Moreover, the optimum ratio for high dispersion stability is confirmed as the addition content of the surfactant. Based on the aforementioned results, the long-term stability of each slurry is analyzed. Turbiscan analysis demonstrates that the agglomeration occurs depending on the increasing amount of surfactant. As a result, we demonstrate that the increased particle size and the decreased content of silica improve the dispersion stability and long-term stability.

• Journal of the Korean Society for Precision Engineering
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• v.19 no.5
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• pp.149-158
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• 2002

Recently, the minimum line width shows a tendency to decrease and the multi-level increases in semiconductor. Therefore, a planarization technique is needed and chemical mechanical polishing(CMP) is considered as one of the most suitable process. CMP accomplishes a high polishing performance and a global planarization of high quality. However there are several defects in CMF, such as micro-scratches, abrasive contaminations and non-uniformity of polished wafer edges. Wet etching process including spin-etching can eliminate the defects of CMP. It uses abrasive-free chemical solution instead of slurry. On this study, ILD(Interlayer-Dielectric) was removed by CMP and wet etching process using DHF(Diluted HF) in order to investigate the possibility of planrization by wet etching mechanism. In the thin film wafer, the results were evaluated from the viewpoint of material removal rate(MRR) and within wafer non-uniformity(WIWNU). And the pattern step heights were also compared for the purpose of planarity characterization of the patterned wafer. Moreover, Chemical polishing process which is the wet etching process with mechanical energy was introduced and evaluated for examining the characteristics of planarization.

• Journal of KIISE:Computer Systems and Theory
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• v.37 no.1
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• pp.43-54
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• 2010

The existing timeout based cache leakage management techniques reduce the leakage energy consumption of the cache significantly by switching off the power supply to the inactive cache line. Since these techniques were mainly proposed for single-processor systems, their efficiency is reduced significantly in multiprocessor systems with a shared L2 cache because of the cache interferences among simultaneously executing tasks. In this paper, we propose a novel cache partition strategy which partitions the shared L2 cache considering the inactive cycles of the cache line. Furthermore, we propose the adaptive task-aware timeout management technique which considers the characteristics of each task and adapts the timeout dynamically. Experimental results from the simulation show that the proposed technique reduces the leakage energy consumption of the shared L2 cache by 73% for the 2-way CMP and 56% for the 4-way CMP on average compared to the existing representative leakage management technique, respectively.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.30 no.5
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• pp.417-427
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• 2008

The aim of this study is to investigate the effect of anodizing surface to osseointegration of implant by using of resonance frequency analysis (RFA), quantitative and qualitative assessment of an anodically modified implant type with regard to osseous healing qualities. A total of 96 screw-shaped implants were prepared for this study. 72 implants were prepared by electrochemical oxidation with different ways. 24 (group 1 SP) were prepared at galvanostatic mode in 0.25M sulfuric acid and phosphoric acid. 24 (group 2GC) were prepared at galvanostatic mode in calcium glycerophosphate and calcium acetate and 24 (group 3 CMP (Calcium Metaphosphate) Coating were prepared at galvanostatic mode in 0.25M sulfuric acid and phosphoric acid followed by CMP coating. Rest of 24 (control group were as a control group of RBM surface. Bone tissue responses were evaluated by resonance frequency analysis (RFA) that were undertaken at 2, 4 and 6 weeks after implant placement in the mandible of mini-pig. Group 1 SP (anodized with sulfuric acid and phosphoric acid implants) demonstrated slightly stronger bone responses than control Group RBM. Group 2 GC (anodized surface with calcium glycerophosphate and calcium acetate implants) demonstrated no difference which were compared with control group. Group 3 GMP (anodized and CMP coated implants) demonstrated slightly stronger and faster bone responses than any other implants. But, all observation result of RF A showed no significant differences between experimental groups with various surface type. Histomorphometric evaluation demonstrated significantly higher bone-to-implant contact for group 2 GC. Significantly more bone formation was found inside threaded area for group 2 GC. It was concluded that group 2 GC (anodized surface with calcium glycerophosphate and calcium acetate implants) showed more effects on the bone tissue responses than RBM surface in initial period of implantation. In addition, CMP showed a tendency to promote bone tissue responses.

• Journal of the Korean Society for Precision Engineering
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• v.19 no.10
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• pp.156-162
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• 2002

There are many factors affecting the results of CMP (Chemical Mechanical Polishing). Among them, the temperature is related to the removal rate and WIWNU (Within Wafer Non-Uniformity). In other words, the removal rate is proportional to the temperature and the variation of temperature distribution on a pad affects the non-uniformity within a wafer. In the former case, the active chemistry improves the rate of chemical reaction and the removal rate becomes better. But, there are not many advanced studies. In the latter case, a kinematical analysis between work-piece and pad can be obtained. And such result analysed from the mechanical aspect can be directly related to the temperature distribution on a pad affecting WIWNU. Meanwhile, the temperature change affects the quantities of both slurry and pad. The change of a pH value of the slurry chemistry due to a temperature variation affects the surface state of an abrasive particle and hence the agglomeration of abrasives happens above the certain temperature. And the pH alteration also affects the zeta potential of a pad surface and therefore the electrical force between pad and abrasive changes. Such results could affect the removal rate and etc. Moreover, the temperature changes the 1st and 2nd elastic moduli of a pad which are closely related to the removal rate and the WIWNU.