• Title, Summary, Keyword: Flow pattern defect

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Thermal behavior of Flow Pattern Defect and Large Pit in Czochralski Silicon Crystals and Their Effects on Device Yield. (Czochralski 법으로 제조된 실리콘 단결정 내의 Flow Pattern Defect와 Large Pit의 열적 거동 및 소자 수율에의 영향)

  • 송영민;조기현;김종오
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • pp.17-20
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    • 1998
  • Thermal behavior of Flow Pattern Defect (FPD) and Large Pit (LP) in Czochralski Silicon crystals was investigated by applying high temperature ($\geq$1100$^{\circ}C$) annealing and non-agitation Secco etching. For evaluation of the effect of LP upon device performance / yield, DRAM and ASIC devices were fabricated. The results indicate that high temperature annealing generates LPs whereas it decreases FPD density drastically, and LP does not have detrimental effects on the performance /

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Thermal Behavior of Flow Pattern Defect and Large Pit in Czochralski Silicon Crystals and Effects of Large Pit upon Device Yield (쵸크랄스키 Silicon 단결정의 Large Pit과 Flow Pattern defect의 열적 거동과 Large Pit의 소자 수율에의 영향)

  • Song, Yeong-Min;Mun, Yeong-Hui;Kim, Jong-O;Jo, Gi-Hyeon
    • Korean Journal of Materials Research
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    • v.11 no.9
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    • pp.781-785
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    • 2001
  • The thermal behavior of Flow Pattern Defect (FPD) and Large Pit (LP) in Czochralski Silicon crystal was investigated by applying high temperature annealing ($\geq$$1100^{\circ}C$) and non-agitated Secco etching. For evaluation of the effect of LP upon device performance/yield, commercial DRAM and ASIC devices were fabricated. The results indicated that high temperature annealing generates LPs whereas it decreases FPD density drastically. However, the origins of FPD and LP seemed to be quite different by not showing any correspondence to their density and the location of LP generation and FPD extinction. By not showing any difference between the performance/yield of devices whose design rule is larger than 0.35 $\mu\textrm{m}$, LP seemed not to have detrimental effects on the performance/yield.

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A Study on Cause of Defects in NIL Molding Process using FEM (유한요소 해석을 이용한 나노임프린트 가압 공정에서 발생하는 결함 원인에 대한 연구)

  • Song, N.H.;Son, J.W.;Kim, D.E.;Oh, S.I.
    • Proceedings of the Korean Society for Technology of Plasticity Conference
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    • pp.364-367
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    • 2007
  • In nano-imprint lithography (NIL) process, which has shown to be a good method to fabricate polymeric patterns, several kinds of pattern defects due to thermal effects during polymer flow and mold release operation have been reported. A typical defect in NIL process with high aspect ratio and low resist thickness pattern is a resist fracture during the mold release operation. It seems due to interfacial adhesion between polymer and mold. However, in the present investigation, FEM simulation of NIL molding process was carried out to predict the defects of the polymer pattern and to optimize the process by FEA. The embossing operation in NIL process was investigated in detail by FEM. From the analytical results, it was found that the lateral flow of polymer resin and the applied pressure in the embossing operation induce the weld line and the drastic lateral strain at the edge of pattern. It was also shown that the low polymer-thickness result in the delamination of polymer from the substrate. It seems that the above phenomena cause the defects of the final polymer pattern. To reduce the defect, it is important to check the initial resin thickness.

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99mTc-DISIDA HEPATOBILIARY SCINTIGRAM IN EVALUATION OF CLONORCHIS SINENSIS INFESTATION IN ENDEMIC REGION (간흡충증 간염에서의 $^{99m}Tc-DISIDA$ 간담도스캔)

  • Yum, Ha-Yong
    • The Korean Journal of Nuclear Medicine
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    • v.19 no.2
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    • pp.25-41
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    • 1985
  • 간흡충증은 한국 및 동남아세아에 널리 분포되어 있는 중요한 풍토병의 하나로서 진단은 전통적으로 분변검사에 의존하여 오고 있다. 최근 들어 담관내 간흡충 및 이의 합병증의 진단을 위해 ERCP 및 contrast cholangiogram등이 시도되었으나 실제에 이용하기에는 많은 제약이 있다 하겠다. 저자는 간흡충증에 있어서 최근 소개된 $^{99m}Tc-DISIDA$ hepatobiliary scintigraphy의 진단적 의의를 규명하고자 1982년부터 1983년까지 고신의대 부속 복음병원에서 검진한 간흡충증 환자 90명을 대상으로 하여 $^{99m}Tc-DISIDA$ hepatobiliary scintigraphy와 formalin-ether 원침법에 의한 분변검사를 시행하였다. $^{99m}Tc-DISIDA$ scintigram소견은 간내 담관 bile flow 및 총수담관 bile flow defect, 그리고 간세포기능의 정도에 따라 자료를 분석하였고 그외 합병증의 진단은 병록 기록, 수술 소견, ERCP 등에 의존하여 결론을 얻었다. $^{99m}Tc-DISIDA$ scintigraphy는 특이한 양상의 bile flow dynamics를 나타내었으며 간내 주담관의 intermittent irregular focal bile flow defect 및 tile flow stasis를 나타내고 말초담관의 bile flow defect는 경미하고 60분 내에 담관 bile flow activity의 완전한 배설을 나타내는 경우를 mild pattern, 간내 담관의 심한 irregular bile flow dynamics 및 간내담관의 심한 irregularity (담관내벽의 심한 불규칙성), 총수담관, 간내 주담관 및 말초 담관까지 심하게 irregular bile flow stasis를 나타내며 bile flow activity의 완전 베설이 $60\sim90$분사이 혹은 90분이상까지 인지된 경우를 moderate-severe pattern으로 분류하였다. 1) 분변검사상 간흡충증은 95검사중 70검사(환자 86명중 67명)에서 양성을 보여 분변 충난검사의 양성율은 73.7%였고 음성율은 26.3%였다. 2) $^{99m}Tc-DISIDA$ hepatobiliary scintigraphy는 90명중 70명에서 특이한 Cs-bile flow양성을 보였으며 양성율은 77.8%였으며 음성율은 22.2%였다. 3) $^{99m}Tc-DISIDA$ hepatobiliary scintigram양성율을 나타낸 환자 70명중 11명은 mild pattern, 59명은 moderate-severe pattern을 나타냈으며 그중 21명은 여러가지 간세포 기능 및 담관에 영향을 미치는 질환과 합병했지만 특이한 Cs-bile flow pattern을 dominent하게 나타내었으며 합병된 여러 질환들도 bile flow pattern상 인지 할 수 있었다. 4) $^{99m}Tc-DISIDA$ hepatobiliary scintigram 음성율을 나타낸 환자 20명중 8명은 만성간염, 5명은 간경변증, 3명은 재발성 농양성담관염(recurrent pyogenic cholangitis)과 간내담도의 stricture 및 담관담석증이 합병되었으며 scintigram상 합병증의 pattern을 나타냈고 4명에서는 low CBD obstruction을 나타내었으며 후에 CBD stone, CBD carcinoma, gall bladder Ca.의 porta hepatis 전이 및 clonorchis worms의 cluster에 의한 obstruction이 operation 및 ERCP로서 진단 되었다. 5) $^{99m}Tc-DISIDA$ hepatobiliary scintigraphy pattern은 현재의 자각증상과 관계된 dominent disease를 나타내었으며, 공간 점유병소도 multiple project images를 시행하므로서 쉽게 발견할 수 있었다. 이와 같이 간흡충증에 있어서 $^{99m}Tc-DISIDA$ hepatobiliary scintigram은 환자의 자각증상과 관계된 질환을 규명하는 데 필요한 정보를 얻었을 수 있었으며 간내담관의 damage정도를 규명하는데 필요한 procedure임이 판명되었다.

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Study for Permanent Mold Design Technology and Porosity Defect Prediction Method by Multi-Phase Flow Numerical Simulations (다상유체해석을 통한 기포결함 예측과 금형설계기술)

  • Choi Y. S.;Cho I. S.;Hwang H. Y.;Choi J. K.;Hong J. H.
    • Transactions of Materials Processing
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    • v.14 no.3
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    • pp.224-232
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    • 2005
  • The high-pressure die-casting is one of the most effective methods to produce a large amount of products in short cycle time. This process, however, has a problem that the gas porosity defect appears easily. The generation of gas porosity is known mainly due to the air entrapment during the injection stage. Most of numerical simulations for the molten metal flow pattern observations have done in the treating of one phase fluid flow but the gas-liquid interface is essentially multi- phase phenomenon. In this paper, the two-phase fluid flow numerical simulation methods have been adapted to predict the gas porosity generations in the molten metal. The accuracy and the usefulness of the new simulation module have been emphasized and verified through some comparison experiments.

Defect Detection of Wall Thinned Straight Pipe using Shearography and Lock-in Infrared Thermography (전단간섭계와 적외선열화상을 이용한 감육 직관의 결함검출)

  • Kim, Kyeong-Suk;Jung, Hyun-Chul;Chang, Ho-Seob;Kim, Ha-Sig;La, Sung-Won
    • Journal of the Korean Society for Precision Engineering
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    • v.26 no.11
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    • pp.55-61
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    • 2009
  • The wall thinning defect of nuclear power pipe is mainly occurred by the affect of the flow accelerated corrosion (FAC) of fluid. This type of defect becomes the cause of damage or destruction of in carbon steel pipes. Therefore, it is very important to measure defect which is existed not only on the welding part but also on the whole field of pipe. This study use dual-beam Shearography, which can measure the out-of-plane deformation and the in-plane deformation by using another illuminated laser beam and simple image processing technique. And this study proposes Infrared thermography, which is a two-dimensional non-contact nondestructive evaluation that can detect internal defects from the thermal distribution by the inspection of infrared light radiated from the object surface. In this paper, defect of nuclear power pipe were, measured using dual-beam shearography and infrared thermography, quantitatively evaluated by the analysis of phase map and thermal image pattern.

Analytic and Numerical Study for air Bubble Defect of UV-NIL Process (UV-NIL 공정의 기포 결함에 대한 해석적 및 수치적 연구)

  • Seok, Jeong-Min;Kim, Nam-Woong
    • Journal of The Korean Society of Manufacturing Technology Engineers
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    • v.21 no.3
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    • pp.473-478
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    • 2012
  • In this paper, the air bubble formation mechanism in the rectangular and triangular line-and-space pattern during dispensing UV Nanoimprint Lithography (UV-NIL) at an atmospheric condition is studied. To investigate the air bubble formation, an analytic model based on geometric approach and a numerical model based on CFD(computational fluid dynamics) were used in the analysis. It was found in the numerical analysis that every time the flow front passed through a corner of the pattern, it proceeded with a newly formed shape, occurring due to interface reconfiguration, since the flow fronts were formed such that they minimized the surface energy. Moreover, the conditions for the air bubble formation were investigated by applying the analytic analysis based on geometric approach and the numerical analysis. Good overall agreement was found between the analytic and numerical analysis.

A Study on Die Casting Process of the Automobile Oil Pan Using the Heat Resistant Magnesium Alloy (내열마그네슘 합금을 이용한 자동차용 오일팬의 다이캐스팅 공정 연구)

  • Shin, Hyun-Woo;Chung, Yeon-Jun;Kang, Seung-Goo
    • Transactions of the Korean Society of Automotive Engineers
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    • v.17 no.3
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    • pp.45-53
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    • 2009
  • Die casting process of Mg alloys for high temperature applications was studied to produce an engine oil pan. The aim of this paper is to evaluate die casting processes of the Aluminium oil pan and in parallel to apply new Mg alloy for die casting the oil pan. Temperature distributions of the die and flow pattern of the alloys in cavity were simulated to diecast a new Mg alloy by the flow simulation software. Dies have to be modified according to material characteristics because melting temperature and heat capacity are different. We changed the shape and position of runner, gate, vent hole and overflow by the simulation results. After several trial and error, oil pans of AE44 and MRI153M Mg alloys are produced successfully without defect. Sleeve filling ratio, cavity filling time and shot speed of die casting machine are important parameter to minimize the defect for die casting Magnesium alloy.

Flow Characteristic of Hybrid-Lower Arm on Casting Parameters in Rheocasting Process (하이브리드 로워암 반응고 사출시 주조변수에 따른 레오캐스팅 충진거동에 대한 연구)

  • Moon, Jun-Young;Kim, Hae-Soo;Lee, Jong-Hyun;Sim, Jae-Gi;Kim, Jae-Min;Jung, Myung-Hwa;Roh, Seung-Kang;Kim, Kang-Wuk;Hong, Chun-Pyo
    • Journal of Korea Foundry Society
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    • v.28 no.5
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    • pp.231-236
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    • 2008
  • H-NCM(Hong-Nanocast Method)has several benefits such as a lower porosity defect and high quality casting comparing to conventional die casting. Influence of casting parameters of hybrid-lower arm in rheocasting process on the slurry flow and the amount of porosity defect was investigated using experimental and simulation methods. In the present study, the Carreau model was adopted to simulate the pattern of rheological flow. Optimal casting paremeters such as injection speed and stroke variations were established. Sound products with integral microstructure and sound shape of joinning different materials of Al and steel pipe without deforming the steel pipe were obtained by the H-NCM slurry and X-ray analysis also showed integral condition throughout the entire parts.

A Study on the Development of Aluminum Piston by Forging Process (알루미늄 단조 피스톤의 개발에 관한 연구)

  • Kim, Y.H.;Bae, W.B.;Kim, H.S.
    • Journal of the Korean Society for Precision Engineering
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    • v.14 no.9
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    • pp.30-36
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    • 1997
  • In this study, the development of an aluminum forged piston was tried to substitute the cast piston, in which there were internal defects such as blow hole and shrink pipe. A gasoline engine piston was chosen as an example for developing the forged piston. Before aluminum forging, model, material (plasticine) test was carried out to investigate the forgeability and internal flow pattern of the forged piston at room temperature. From the result of model material test, an aluminum piston to be forged was redesigned. The aluminum pistion was forged in hot process. The quality of a forged piston was compared with that of a cast piston in the point of mechanical properties, internal defect and microstructure. It was proved that the forged piston was superior to the cast piston.

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