• Transactions on Electrical and Electronic Materials
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• 제7권4호
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• pp.167-172
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• 2006

Submicron colloidal silica coated with ceria were prepared by mixing of silica and nano ceria particles and modified by hydrothermal reaction. The polishing efficiency of the ceria coated silica slurry was tested over oxide film on silicon wafer. By changing the polishing pressure in the range of $140{\sim}420g/cm^2$ with the ceria coated silica slurries in $100{\sim}300nm$, rates, WIWNU and friction force were measured. The removal rate was in the order of 200, 100, and 300 nm size silica coated with ceria. It was known that the smaller particle size gives the higher removal rate with higher contact area in Cu slurry. In the case of oxide film, the indentation volume as well as contact area gives effect on the removal rate depending on the size of abrasives. The indentation volume increase with the size of abrasive particles, which results to higher removal rate. The highest removal rate in 200 nm silica core coated with ceria is discussed as proper combination of indentation and contact area effect.

• Tribology and Lubricants
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• 제25권6호
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• pp.404-408
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• 2009

본 연구에서는 마이크로/나노입자를 이용한 연마가공 공정에서의 입자-표면간 접촉상황에서 접촉계면의 기계적 성질과 재료제거율간의 관계를 실험적으로 고찰하였다. 연마가공 공정에서의 입자-평면간 접촉을 모사하기 위하여 팁 대신 실리카 입자를 부착한 콜로이드 프로브를 이용한 원자현미경 실험을 통하여 마찰력과 강성을 실험적으로 측정하였다. 실험결과와 이론적 접촉해석으로부터, 마찰계수는 횡방향 접촉강성에 따라 대체적으로 증가하고 재료제거율은 실리카 입자와 Cu, PolySi, Ni과 같은 다양한 재료표면간 접촉에서의 마찰계수들과 지수함수적인 비례관계를 가지고 있음을 규명하였다.

• 한국전기전자재료학회논문지
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• 제20권1호
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• pp.74-79
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• 2007

Most studies on copper Chemical Mechanical Planarization (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 various factors related 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 and mechanically analyze the roles of slurry components in the formation of the uniformity in Cu CMP. In this paper, Cu CMP was performed using citric acid($C_{6}H_{8}O_{7}$), hydrogen peroxide($H_{2}O_{2}$), colloidal silica, and benzotriazole($BTA,\;C_{6}H_{4}N_{3}H$) as a complexing agent, an oxidizer, an abrasive, and a corrosion inhibitor, respectively. All the results of this study showed that within-wafer non-uniformity(WIWNU) of Cu CMP could be controlled by the contents of slurry components.

• 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.

• Tribology and Lubricants
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• 제34권6호
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• pp.209-216
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• 2018

Sapphire is a substrate material that is widely used in optical and electronic devices. However, the processing of sapphire into a substrate takes a long time owing to its high hardness and chemical inertness. In order to process the sapphire ingot into a substrate, ingot growth, multiwire sawing, lapping, and polishing are required. The lap grinding process using pellets is known as one of the ways to improve the efficiency of sapphire substrate processing. The lap grinding process ensures high processing efficiency while utilizing two-body abrasion, unlike the lapping process which utilizes three-body abrasion by particles. However, the lap grinding process has a high material removal rate (MRR), while its weakness is in obtaining the required surface roughness for the final polishing process. In this study, we examine the effects of free abrasives in lap grinding on the material removal characteristics of sapphire substrate. Before conducting the lap grinding experiments, it was confirmed that the addition of free abrasives changed the friction force through the pin-on-disk wear test. The MRR and roughness reduction rate are experimentally studied to verify the effects of free abrasive concentration on deionized water. The addition of free abrasives (colloidal silica) in the lap grinding process can improve surface roughness by three-body abrasion along with two-body abrasion by diamond grits.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2008년도 하계학술대회 논문집 Vol.9
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• pp.537-537
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• 2008

Copper (Cu) has been widely used for interconnection structure in intergrated circuits because of its properties such as a low resistance and high resistance to electromigration compared with aluminuim. Damascene processing for the interconnection structure utilizes 2-steps chemical mechanical polishing(CMP). After polishing, the removal of abrasive particles on the surfaces becomes as important as the polishing process. In the paper, buffing process for the removal of colloidal silica from polished Cu wafer was proposed and demonstrated.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2008년도 하계학술대회 논문집 Vol.9
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• pp.545-545
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• 2008

Poly-Si is an essential material for floating gate in NAND Flash memory. To fabricate this material within region of floating gate, chemical mechanical polishing (CMP) is commonly used process for manufacturing NAND flash memory. We use colloidal silica abrasive with alkaline agent, polymeric additive and organic surfactant to obtain high Poly-Si to SiO2 film selectivity and reduce surface defect in Poly-Si CMP. We already studied about the effects of alkaline agent and polymeric additive. But the effect of organic surfactant in Poly-Si CMP is not clearly defined. So we will examine the function of organic surfactant in Poly-Si CMP with concentration separation test. We expect that surface roughness will be improved with the addition of organic surfactant as the case of wafering CMP. Poly-Si wafer are deposited by low pressure chemical vapor deposition (LPCVD) and oxide film are prepared by the method of plasma-enhanced tetra ethyl ortho silicate (PETEOS). The polishing test will be performed by a Strasbaugh 6EC polisher with an IC1000/Suba IV stacked pad and the pad will be conditioned by ex situ diamond disk. And the thickness difference of wafer between before and after polishing test will be measured by Ellipsometer and Nanospec. The roughness of Poly-Si film will be analyzed by atomic force microscope.

• 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.

• 한국화재소방학회논문지
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• 제32권6호
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• pp.108-116
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• 2018

구리 용융흔(Melted bead) 미세조직(Microstructure)은 변형층(Deformed layer)과 원조직(Undeformed layer)으로 구분할 수 있다. 변형층이 존재하는 경우에는 측정오류가 발생되어 연마/미세연마(Grinding/Polishing)를 통하여 변형층을 제거하고 원조직을 관측하여야 한다. 이에 따라 본 연구에서는 구리 용융흔의 미세조직 분석을 위한 연마/미세연마 절차(Process)를 제시하였다. 변형층 제거를 위해 연마재 종류/크기, 연마시간, 연마율의 상관성을 분석하였고 변형층의 두께를 $1{\mu}m$ 이하가 되도록 하였다. 연구결과, 실리콘카바이드 연마재 $15{\mu}m$ (SiC P1200) 2 min, $10{\mu}m$ (SiC P2400) 1 min, 다이아몬드 연마재 $6{\mu}m$ 8 min, $3{\mu}m$ 6 min, $1{\mu}m$ 10 min, $.25{\mu}m$ 8 min 실시하는 새로운 연마/미세연마 절차를 제시하였다. 또한 최종 단계에서 3 min 동안 콜로이달 실리카 $.04{\mu}m$로 화학적 미세연마를 실시함으로써 미세조직의 선명성을 증대시키는 방안도 제시하였다. 연마/미세연마 시간은 총 38 min이 소요되며, 기존에 제시된 시간, 절차보다 단순화 하였다.