• 한국펄프종이공학회:학술대회논문집
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• 한국펄프종이공학회 1999년도 Proceedings of Pre-symposium of the 10th ISWPC
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• pp.43-49
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• 1999

Effectiveness of the microparticle retention systems in improving dramage, retention, formation has been recognized for many years (1, 2, 3, 4, 5). In this study the effectiveness of crosslinked cationic corn starches and silica-based microgels as components of Compozil system has been evaluated. It was shown that improvements in retention and strength could be achieved by employing crosslinked cationic corn starches especially at high conductivity. Silica-based microgels with better performance in retention and dramage than a commercial colloidal silica sol have been made through a reaction of sulfuric acid and sodium silicate solutions.

• 한국재료학회지
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• 제20권2호
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• pp.78-81
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• 2010

Surface modification of silica nanoparticles was investigated using an aerosol self assembly. Stearic acid was used as surface treating agent. A two-fluid jet nozzle was employed to generate an aerosol of the colloidal suspension, which contained 20 nm of silica nanoparticles, surface modifier, and ethyl alcohol. Powder properties such as morphology, specific surface area and pore size distribution were analyzed by SEM, BET and BJH methods, respectively. Surface properties of the silica power were analyzed by FT-IR. The OH bond of the $SiO_2$ surface was converted to a C-H bond. It was revealed that the hydrophilic surface changed to a hydrophobic one due to the aerosol self assembly. Morphology of the surface treated powder was nanostructured with lots of pores having an average diameter of around $2\;{\mu}m$. Depending on the stearic acid concentration (0.25 to 1.0 wt%), the pore size distribution of the particles and the degree of hydrophobicity ranged from 1.5 nm to 180 nm and 29.6% to 50.2%, respectively.

• Tribology and Lubricants
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• 제34권6호
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• pp.226-234
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• 2018

Copper chemical mechanical planarization (CMP) has become a key process in integrated circuit (IC) technology. The results of copper CMP depend not only on the mechanical abrasion, but also on the slurry chemistry. The slurry used for Cu CMP is known to have greater chemical reactivity than mechanical material removal. The Cu CMP slurry is composed of abrasive particles, an oxidizing agent, a complexing agent, and a corrosion inhibitor. Citric acid can be used as the complexing agent in Cu CMP slurries, and is widely used for post-CMP cleaning. Although many studies have investigated the effect of citric acid on Cu CMP, no studies have yet been conducted on the interfacial friction characteristics and step height reduction in CMP patterns. In this study, the effect of citric acid on the friction characteristics and step height reduction in a copper wafer with varying pattern densities during CMP are investigated. The prepared slurry consists of citric acid ($C_6H_8O_7$), hydrogen peroxide ($H_2O_2$), and colloidal silica. The friction force is found to depend on the concentration of citric acid in the copper CMP slurry. The step heights of the patterns decrease rapidly with decreasing citric acid concentration in the copper CMP slurry. The step height of the copper pattern decreases more slowly in high-density regions than in low-density regions.

• Transactions on Electrical and Electronic Materials
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• 제4권2호
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• pp.1-4
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• 2003

The purpose of this study was to investigate the characteristics of slurry including phosphoric acid for chemical-mechanical planarization of copper and tantalum nitride. In general, the slurry for copper CMP consists of alumina or colloidal silica as an abrasive, organic acid as a complexing agent, an oxidizing agent, a film forming agent, a pH control agent and additives. Hydrogen peroxide (H$_2$O$_2$) is the material that is used as an oxidizing agent in copper CMP. But, the hydrogen peroxide needs some stabilizers to prevent decomposition. We evaluated phosphoric acid (H$_3$PO$_4$) as a stabilizer of the hydrogen peroxide as well as an accelerator of the tantalum nitride CMP process. We also estimated dispersion stability and zeta potential of the abrasive with the contents of phosphoric acid. An acceleration of the tantalum nitride CMP was verified through the electrochemical test. This approach may be useful for the development of the 2$\^$nd/ step copper CMP slurry and hydrogen peroxide stability.

• 한국식품과학회지
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• 제24권5호
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• pp.456-462
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• 1992

본 연구는 간장의 속성발효를 위한 방법의 하나로 정어리육을 효소에 의하여 분해하고, 분해액을 유산균과 효모의 균체를 고정화하여 이를 column형 reactor를 이용하여 속성발효를 시도하였다. 이때 사용된 column 반응조는 유리제$(30{\times}50cm)$의 칼럼 3개에 Pediococcus halophilus R-22, Saccharomyces rouxii R-60과 Candida etchellsii H-50을 colloidal silic와 sodium alginate(1 : 5)의 혼합액으로 고정화하여 각각의 column에 충전시켰다. 이때의 최적조건은 pH5.2, 온도 $30^{\circ}C$, 식염농도 10%이었다. 발효 최적조건에서 96시간 경과시 P. halophilus R-22는 유산을 0.75%, S. rouxii R-60은 ethylalcohol을 2.5%, C. etchellsii H-50은 4-ethylguaiacol을 18 mg/l 생성하였다.

• 한국결정성장학회지
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• 제11권1호
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• pp.33-37
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• 2001

$213^{\circ}C$에서 깁사이트와 pseudoboehmite를 출발물질로 하여 산성도를 변화시켜 수열합성법에 의해서 카올리나이트를 합성하였다. 합성된 카올리나이트는 X-선회절 분석기와 적외선 분광광도계를 이용하여 결정화 과정을 조사하였으며 Hinckley 지수를 계산하였다. 산을 이용한 카올리나이트 합성은 출발물질의 용해를 촉진시켜 결정화하였다. 결정화 속도와 적층결함은 음이온의 종류, 산성도와 출발물질에 의존하였다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2006년도 하계학술대회 논문집 Vol.7
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• pp.49-50
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• 2006

The studies on Cu CMP have focused on material removal and its mechanisms. Although many studies have been conducted on the mechanism of Cu CMP, a study on uniformity in Cu CMP is still unknown. Since the aim of CMP is global and local planarization, the approach to uniformity in Cu CMP is essential to elucidate the Cu CMP mechanism as well. The main purpose of the experiment reported here was to investigate the roles of slurry components in the formation of the uniformity in Cu CMP. All the results of in this study showed that the uniformity in Cu CMP could be controlled by the contents of slurry components.

• 한국광물학회지
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• 제19권4호
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• pp.231-238
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• 2006

본 연구에서는 컬럼실험을 통해서 여러 종류의 콜로이드가 같이 존재할 때의 거동을 관찰하였다. 본 실험에서는 일반 pH조건에서 서로 반대의 표면전하를 띠는 ferrihydrite (100 nm; 양전하)와 비정질 $SiO_2$ (40 nm, 80 nm; 음전하) 나노입자들와 음전하를 띠는 $177{\sim}250{\mu}m$의 석영을 고정상으로 이용하였다. 실험결과는, 양전하를 띠는 콜로이드(ferrihydrite)가 존재한다고 하더라도 그 비율이 많지 않으면 음전하를 띠는 콜로이드($SiO_2$)와의 상호작용에 의해서 석영고정상 속을 쉽게 이동될 수 있음을 보여주었다. 이는 자연조건하에서는 양전하를 띠는 오염물질과 음전하를 띠는 오염물질이 동시에 콜로이드에 의해서 이동될 수 있음을 지시한다.

• 한국분말재료학회지
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• 제5권3호
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• pp.199-209
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• 1998

A new low melting inorganic binder, monoclinic $HBO_2$, has been developed for Selective Laser Sintering (SLS) of alumina powder by dehydration process of boron oxide powder in a vacuum oven at $120^{\circ}C$. It led to better green SLS parts and higher bend strength far green and fired parts compared to other inorganic binders such as aluminum and ammmonium phosphate. This appeared to be due to its low viscosity and better wettability of the alumina particle surface. A low density single phase ceramic, aluminum borate ($Al_{18}B_4O_{33}$), and multiphase ceramic composites, $A_{12}O_3-A_{14}B_2O_9$, were successfully developed by laser processing of alumina-monoclinic $HBO_2$ powder blends followed by post-thermal processing; both $Al_{18}B_4O_{33}$ and $A_{14}B_2O_9$ have whisker-like grains. The physical and mechanical properties of these SLS-processed ceramic parts were correlated to the materials and processing parameters. Further densification of the $A_{12}O_3-A_{14}B_2O_9$ ceramic composites was carried out by infiltration of colloidal silica, and chromic acid into these porous SLS parts followed by heat-treatment at high temperature ($1600^{\circ}C$). The densities obtained after infiltration and subsequent firing were between 75 and 80% of the theoretical densities. The bend strengths are between 15 and 33 MPa.

• 대한화학회지
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• 제37권3호
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• pp.317-326
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• 1993

변형된 ZSM-5 제올라이트 촉매에서 톨루엔의 n-프로필알코올에 대한 산촉매 반응이 조사되었고, 이알킬벤젠 이성질체들의 100$^{\circ}C$에서의 흡착 실험이 수행되었다. 4-프로필암모늄이온, 알루민산나트륨, 콜로이달실리카 등으로부터 수열반응에 의하여 ZSM-5가 합성되었으며, H-, K-, Sr-, P-Mg-HZSM-5, H-Y 및 H-모더나이트 등이 전통적인 방법에 의하여 만들어졌다. HZSM-5에서 톨루엔의 n-프로필알코올에 의한 주반응생성물은 크실렌, 프로필톨루엔 뿐만 아니라 에틸톨루엔을 포함하며, P-Mg-HZSM-5에서는 이알킬벤젠 이성질체중 높은 파라 선택성이 얻어졌다. 다양한 p-이성질체들의 확산계수는 1 ${times}$ 10$^{-10}$ cm$^2$/sec로 일정했으며 o-이성질체보다 m-이성질체가 10배 이상 느리게 나타났다. 이들 반응 및 흡착특성이 제올라이트의 세공구조에 의한 형상 선택성, 제올라이트의 산성도 등의 관점에서 해석되었다.