• 제목/요약/키워드: Preferential Removal

검색결과 25건 처리시간 0.027초

화학기계적폴리싱(CMP)에 의한 층간절연막의 광역평탄화에 관한 연구 (A Global Planarization of Interlayer Dielectric Using Chemical Mechanical Polishing for ULSI Chip Fabrication)

  • 정해도
    • 한국정밀공학회지
    • /
    • 제13권11호
    • /
    • pp.46-56
    • /
    • 1996
  • Planarization technique is rapidly recognized as a critical step in chip fabrication due to the increase in wiring density and the trend towards a three dimensional structure. Global planarity requires the preferential removal of the projecting features. Also, the several materials i.e. Si semiconductor, oxide dielectric and sluminum interconnect on the chip, should be removed simultaneously in order to produce a planar surface. This research has investihgated the development of the chemical mechanical polishing(CMP) machine with uniform pressure and velocity mechanism, and the pad insensitive to pattern topography named hard grooved(HG) pad for global planarization. Finally, a successful result of uniformity less than 5% standard deviation in residual oxide film and planarity less than 15nm in residual step height of 4 inch device wafer, is achieved.

  • PDF

법랑질(琺瑯質)과 상아질(象牙質)의 산처리후(酸處理後)의 전자현미경(電子顯微鏡) 소견(所見)에 관(關)한 연구(硏究) (A STUDY ON ELECTRON-MICROSCOPIC FINDINGS AFTER ACID ETCHING ON ENAMEL AND DENTIN)

  • 김영해
    • Restorative Dentistry and Endodontics
    • /
    • 제9권1호
    • /
    • pp.115-119
    • /
    • 1983
  • The purpose of this study was to compare the solubility of enamel and dentin to an etchant after fluoride application. Specimens were collected from extracted anterior and bicuspid and each tooth was cut into several pieces. These specimen were allocated in 7 group; 1%, 2%, 3% NaF, 1%, 8%, 20% $SnF_2$, and control group. Five specimens in each group was exposed to pre-determined fluoride solution for 3 minutes, and washed with running water. These specimens were etched by Hipol (commercial label) etchant for 30 seconds. Following are the findings obtained through S.E.M. 1. All specimens with acid etching revealed preferential removal of prism periphery leaving prism core. 2. Specimens treated with 1%, 2% NaF solution showed that the shape of prism tip was thin and sharp like a needle. The case of 3% NaF showed rather round shape at prism end. 3.1% of $SnF_2$ case showed similar findings with the control group but 8% and 20% $SnF_2$ case revealed needle shape at the prism and was less clear than NaF case. Preferential removal of prism periphery was partialy observed and un decalcified area is fused to prism forming reidge. 4. Dentine treated by fluoride compound in low concentration showed the orifice of dentinal tubule was clearly enlarged whereas in high concentration the orifice was not widened.

  • PDF

수냉식 방열을 이용한 연료전지용 PROX 반응기의 성능에 관한 실험적 연구 (Experimental Study on the Preferential Oxidation Reactor Performance Using a Water Cooling Heat Removal for Polymer Electrolyte Membrane Fuel Cell)

  • 김진산;조태현;구본찬;이도형
    • 한국수소및신에너지학회논문집
    • /
    • 제27권5호
    • /
    • pp.503-509
    • /
    • 2016
  • Fuel cell is a device for producing electricity by using the hydrogen produced by the fuel processor. At this time, CO is also created by the fuel processor. The resulting CO enters the stack where is produce electricity and leads to the adsorption of anode catalyst, finally the CO poisoning occurs. Stack which occurred CO poisoning has a reduction in performance and shelf life are gradually fall because they do not respond to hydrogen. In this paper, experiments that using a PROX reactor to prevent CO poisoning were carried out for removing the CO concentration to less than 10ppm range available in the fuel cell. Furthermore experiments by the PROX reaction was designed and manufactured with a water-cooling heat exchange reactor to maintain a suitable temperature control due to the strong exothermic reaction.

Poly-Si Cell with Preferential Grain Boundary Etching and ITO Electrode

  • Lim, D.G.;Lee, S.E.;Park, S.H.;Yi, J.
    • 태양에너지
    • /
    • 제19권3호
    • /
    • pp.125-131
    • /
    • 1999
  • This paper deals with a novel structure of poly-Si solar cell. A grain boundary(GB) of poly-Si acts as potential barrier and recombination center for photo-generated carriers. To reduce unwanted side effects at the GB of poly-Si, we employed physical GB removal of poly-Si using chemical solutions. Various chemical etchants such as Sirtl, Yang, Secco, and Schimmel were investigated for the preferential GB etching. Etch depth about 10 ${\mu}m$ was achieved by a Schimmel etchant. After a chemical etching of poly-Si, we used $POCl_3$ for emitter junction formation. This paper used an easy method of top electrode formation using a RF sputter grown ITO film. ITO films with thickness of 300 nm showed resistivity of $1.26{\times}10^{-4}{\Omega}-cm$ and overall transmittance above 80%. Using a preferential GB etching and ITO top electrode, we developed a new fabrication procedure of poly-Si solar cells. Employing optimized process conditions, we were able to achieve conversion efficiency as high as 16.6% at an input power of 20 $mW/cm^2$. This paper investigates the effects of process parameters: etching conditions, ITO deposition factors, and emitter doping densities in a poly-Si cell fabrication procedure.

  • PDF

AFM and Specular Reflectance IR Studies on the Surface Structure of Poly(ethylene terephthalate) Films upon Treatment with Argon and Oxygen Plasmas

  • Seo, Eun-Deock
    • Macromolecular Research
    • /
    • 제12권1호
    • /
    • pp.134-140
    • /
    • 2004
  • Semi-crystalline poly(ethylene terephthalate) (PET) film surfaces were modified with argon and oxygen plasmas by radio-frequency (RF) glow discharge at 240 mTorr/40 W; the changes in topography and surface structure were investigated by atomic force microscopy (AFM) in conjunction with specular reflectance of infrared microspectroscopy (IMS). Under our operating conditions, analysis of the AFM images revealed that longer plasma treatment results in significant ablation on the film surface with increasing roughness, regardless of the kind of plasma used. The basic topographies, however, were different depending upon the kind of gas used. The specular reflectance analysis showed that the ablative mechanisms of the argon and oxygen plasma treatments are entirely different with one another. For the Ar-plasma-treated PET surface, no observable difference in the chemical structure was observed before and after plasma treatment. On the other hand, the oxygen-plasma-treated PET surface displays a significant decrease in the number of aliphatic C-H groups. We conclude that a constant removal of material from the PET surface occurs when using the Ar-plasma, whereas preferential etching of aliphatic C-H groups, with respect to, e.g. , carbonyl and ether groups, occurs upon oxygen plasma.

Removal of Heavy Metal Ions by Electrocoagulation for Continuous Use of Fe2+/Fe3+-Mediated Electrochemical Oxidation Solutions

  • Jung, Youn-Su;Pyo, Myoung-Ho
    • Bulletin of the Korean Chemical Society
    • /
    • 제29권5호
    • /
    • pp.974-978
    • /
    • 2008
  • Removal of heavy metal ions ($Cd^{2+}$ and $Zn^{2+}$) by electrocoagulation (ECG) was investigated in an acidic condition, which is necessary for re-using or discharging the mediated electrochemical oxidation (MEO) media. Effects of various parameters such as electrolytes, current densities, and electrode materials were examined for a metal-contaminated MEO system using $Fe^{2+}/Fe^{3+}$ pairs as a mediator. It was found that ECG with Al electrodes is greatly affected by the presence of $Fe^{2+}$. [$Cd^{2+}$] and [$Zn^{2+}$] remain constant until [$Fe^{2+}$] reaches a certain concentration level (ca. 10 mM). This preferential removal of $Fe^{2+}$ during ECG with Al electrodes is not alleviated by controlling current densities, potential programs, and solution mixing. ECG with Fe electrodes, on the other hand, resulted in relatively fast removal of $Cd^{2+}$ and $Zn^{2+}$ under coexistence of $Fe^{2+}$, indicative of the different role between $Fe^{n+}$ generated from an electrode and $Fe^{2+}$ initially present in a solution. When ECG was performed with Fe electrodes until [$Fe^{n+}$] became the same as the concentration of initially present $Fe^{2+}$, [$Cd^{2+}$] and [$Zn^{2+}$] were reduced to one-tenth of the initial concentrations, suggesting the possibility of a continuous use of the medium for a subsequent MEO process.

PCB 제조공정에서 발생하는 VOC를 처리하기 위한 흡착제를 흡착특성 (Adsorption Characteristics of ACF for the Removal of VOCs in the PCB Manufacturing Process)

  • 신창섭;김기환;원정일
    • 한국대기환경학회지
    • /
    • 제17권1호
    • /
    • pp.67-74
    • /
    • 2001
  • In the manufacturing process of PCB , three kinds of VOCs such as aceton, methanol and 2-metoxyethanol are being used. In this study, adsorption characteristics of activated carbon fibers(ACFs) and active carbon were examined to temove these VOCs. The experimental results showed that ACF has better adsorption and regeneration efficiency than activated carbon. Phenolic-resin based ACF showed the highest adsorption capacity and the capacity was not decreased after repeated regeneration by steam. On the adsorption and desorption experiments for ternary components, preferential adsorption with roll-over phenomena was appeared. 2-Metoxyethanol was strong adsorbaste and it displaced adsorbed methanol and aceton.

  • PDF

Improving of Corrosion Resistance of Aluminum Alloys by Removing Intermetallic Compound

  • Seri, Osami
    • Corrosion Science and Technology
    • /
    • 제7권3호
    • /
    • pp.158-161
    • /
    • 2008
  • It is well known that iron is one of the most common impurity elements found in aluminum and its alloys. Iron in the aluminum forms an intermetallic compounds such as $FeAl_3$. The $FeAl_3$ particles on the aluminum surface are one of the most detrimental phases to the corrosion process and anodizing procedure for aluminum and its alloys. Trial and error surface treatment will be carried out to find the preferential and effective removal of $FeAl_3$ particles on the surfaces without dissolution of aluminum matrix around the particles. One of the preferable surface treatments for the aim of getting $FeAl_3$ free surface was an electrochemical treatment such as cathodic current density of $-2kAm^{-2}$ in a 20-30 mass% $HNO_3$ solution for the period of 300s. The corrosion characteristics of aluminum surface with $FeAl_3$ free particles are examined in a $0.1kmol/m^3$ NaCl solution. It is found that aluminum with free $FeAl_3$ particles shows higher corrosion resistance than aluminum with $FeAl_3$ particles.

Enantiospecific Membrane Processes

  • Giorno, Lidietta
    • Korean Membrane Journal
    • /
    • 제1권1호
    • /
    • pp.38-42
    • /
    • 1999
  • Membrane technology can be applied in two ways to produce pure enantiomers. In one case a membrane separation process can be cmbined with an enantiospecific reaction to obtain so-called 'en-antiospecific membrane reacto' These systems are useful to carry out asymmetric synthesis or kinetic resolution and simulatneously separate the produced enantiomer. As for general membrane reactors the result is a more compact system with a higher conversion: in fact removal of a product drives equilibrium-limited reactions towards completion. The other way to apply membrane technology to chiral production is the use of intrinsically enantioselective membranes that are able to distinguish between two isomers favouring preferential transport of only one isomer in absence of reaction. In this paper the current development of chiral membrane processes will be discussed.

  • PDF

구리로 이온교환된 NaY 제올라이트에 의한 유기 황 화합물들의 흡착제거 비교연구 (Comparative Study on Adsorptive Removal of Organic Sulfur Compounds over Cu-Exchanged NaY Zeolites)

  • 정갑순;이석희;천재기;박동호;우희철
    • Korean Chemical Engineering Research
    • /
    • 제48권4호
    • /
    • pp.534-539
    • /
    • 2010
  • 메탄 속에 포함되어 있는 TBM, THT, DMS 등의 유기 황 화합물에 대한 흡착 제거가 NaY와 CuNaY 제올라이트를 이용하여 303 K, 대기압 조건하에서 수행되었다. 삼성분계 흡착시스템 실험을 통해, NaY에서는 THT의 선택적 흡착이 목격되었으며, CuNaY에서는 모든 유기 황 화합물의 동시 흡착이 일어났다. 이러한 현상은 파과흡착곡선, 승온탈착, 겉보기 탈착 활성화 에너지 등의 실험결과로 부터 설명될 수 있었다. 황에 대한 흡착능은 CuNaY(2.90~3.20 mmol/g)가 NaY(0.70~0.90 mmol/g)보다 매우 우수하였다. 본 연구결과는 CuNaY에 존재하는 $Cu^{1+}$ 흡착점과 강한 산의 세기가 황 원자와의 강한 상호작용을 유발하여 높은 황 흡착능을 갖게 하는 것으로 이해된다.