• 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.

• Applied Chemistry for Engineering
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• v.10 no.2
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• pp.252-258
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• 1999

Tetramethyl orthosilicate (TMOS) was obtained by the direct synthesis of methanol with metallic silicon including copper compound as a catalyst and zinc compound as a promoter. The effects of the preheating temperature and the preparation method of the contact mass on TMOS synthesis were investigated. The composition effects of the contact mass which was composed of metallic silicon with copper catalyst and various metallic halide promoters including Zn, Sn or Cd compound were studied also. The best performance on TMOS synthesis was observed on a mixed bed reactor containing metallic silicon preheated with CuCl as a catalyst and $ZnCl_2$ as a promoter. When Cu/Si = 7 wt %, Zn/Cu = 7 wt % was mixed in a slurry phase and activated into contact mass at $380^{\circ}C$, the average selectivity was 87.2% in the silicon consumption of 69.2% at $220^{\circ}C$.

• Journal of Chest Surgery
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• v.36 no.10
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• pp.721-727
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• 2003

Background: Parenteral tetracycline is no longer available for pleural sclerosing agent for pleurodesis in Korea due to the discontinuation of the production. The purposes of this study were to determine whether oral doxycycline (ODC) could be used as an effective sclerosing agent for pleurodesis, and to compare the effectiveness of ODC to other agents, such as homologous blood and talc. Material and Method: Twenty male rats were divided into four groups (A to D). Following agents were given to each group intrapleurally; 10 $m\ell$/kg of 0.9% saline to group A, 10 mg/kg of ODC to group B, 2 $m\ell$/kg of homologous blood to group e, and 70 mg/kg of talc slurry to group D. All animals were sacrificed 28 days after instillation. The pleural spaces were assessed grossly and microscopically and were graded from 0 to 3, and the thicknesses of the pleura were measured. Result: The gross score of group A was 0.0, group B was 1.4$\pm$0.9, group e was 1.0$\pm$0.7, and group D was 2.2$\pm$0.8. Significant adhesion were examined in group B and D grossly (p < 0.05). The pleural thickness of group A was 0.7$\pm$0.2 /10$^2$ mm, group B was 1.2$\pm$0.4 /10$^2$ mm, group C was 1.4$\pm$0.4 /10$^2$ mm, and group D was 3.5$\pm$0.9 /10$^2$ mm. Group D showed pleural thickening significantly (p < 0.05). The microscopic score of group A was 1.0, group B was 1.7$\pm$0.5, group e was $1.5\pm$0.4, and group D was 2.8$\pm$0.4. Group B and D showed significant inflammations and depositions of collagen (p < 0.05). Conclusion: ODC showed significant pleurodesis grossly and microscopically, and homologous blood did not show adhesion. Talc was a significant sclerosing agent for pleurodesis causing extensive inflammation and collagen depisotion.