• Title/Summary/Keyword: In-situ particle size

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Performance Characteristics of In-Situ Particle Monitors at Sub-Atmospheric Pressure (감압상태에서의 In-Situ Particle Monitor의 성능특성)

  • Bae, Gwi-Nam
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.22 no.11
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    • pp.1564-1570
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    • 1998
  • In-situ particle monitors(ISPMs) are widely used for monitoring contaminant particles in vacuum-based semiconductor manufacturing equipment. In the present research, the performance of a Particle Measuring Systems(PMS) Vaculaz-2 ISPM at subatmospheric pressures has been studied. We created uniform upstream conditions of particle concentration and measured the detection efficiency, the lower detection limit, and the size response of the ISPM using uniform sized methylene blue aerosol particles. The effect of particle size, particle velocity, particle concentration, and system pressure on the detection efficiency was examined. Results show that the detection efficiency of the ISPM decreases with decreasing chamber pressure, and with increasing mass flow rate. The lower detection limit of the ISPM, determined at 50 % of the measured maximum detection efficiency, was found to be about $0.15{\sim}0.2{\mu}m$, which is similar to the minimum detectable size of $0.17{\mu}$ given by the manufacturer.

In situ Particle Size and Volume Concentration of Suspended Sediment in Seomjin River Estuary, Determined by an Optical Instrument,'LISST-100' (현장입도분석기를 이용한 섬진강하구 부유퇴적물의 특성 연구)

  • KIM Seok Yun;LEE Byoung Kwan
    • Korean Journal of Fisheries and Aquatic Sciences
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    • v.37 no.4
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    • pp.323-329
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    • 2004
  • In situ particle size and volume concentration of suspended sediment was measured at the mouth of Seomjin River Estuary In February 2001, using an optical instrument, 'LISST-100'. Time variation of in situ particle size and concentration shows: (1) during ebb tide, Seomjin River supplies relatively fine-grained particles with less-fluctuated, compared to during flood tide, and well-behaved concentrations following the tidal cycle; and (2) during flood tide, relatively coarse-grained particles with highly variable in size distribution and concentration flow upstream from Kwangyang Bay. This explains a poor correlation $(r^{2}=0.10)$ between sediment concentration and beam attenuation coefficient during flood and a high degree of correlation $(r^{2}=0.80)$ during ebb tide. Relatively fine grained and well defined, monotonous size distribution may promote the correlation between concentration and beam attenuation coefficient due to optical homogeneity of particles during ebb tide. Abundance of large aggregates with time-varying size and shape distributions may be mainly responsible for variations in optical properties of the sediment during flood tide, and thus may confound the relationship between the two variables. The difference in particle sizes and shapes between flood and ebb tides can also be observed on SEM images.

Investigation of the Performance Characteristics of an In-Situ Particle Monitor at Low Pressures Using Aerodynamic Lenses (저압상태에서 공기역학적 렌즈를 이용한 In-Situ Particle Monitor의 성능특성 분석)

  • Bae, Gwi-Nam
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.24 no.10
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    • pp.1359-1367
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    • 2000
  • In-situ particle monitors(ISPMs) are widely used for monitoring contaminant particles in vacuum-based semiconductor manufacturing equipment. In the present research, the performance of a Particle Measuring Systems(PMS) Vaculaz-2 ISPM at low pressures has been studied. We generated the uniform sized methylene blue particle beams using three identical aerodynamic lenses in the center of the vacuum line, and measured the detection efficiency of the ISPM. The effects of particle size, particle concentration, mass flow rate, system pressure, and arrangement of aerodynamic lenses on the detection efficiency of the ISPM were examined. Results show that the detection efficiency of the ISPM greatly depends on the mass flow rate, and the particle Stokes number. We also found that the optimum Stokes number ranges from 0.4 to 1.9 for the experimental conditions.

In-situ Particle Characterization of Cu Nanopowder using Scanning Mobility Particle Sizer in Pulsed Wire Evaporation Method (전기폭발법에서 SMPS를 이용한 Cu 나노분말의 실시간 입자특성평가)

  • 이창우;맹덕영;박중학;유지훈;이재훈;이창규;김흥회
    • Journal of Powder Materials
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    • v.10 no.4
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    • pp.275-280
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    • 2003
  • Synthesis and characteristics of Cu nanopowder were considered by in-situ characterization method using SMPS in pulsed wire evaporation process. With increasing pressure in chamber, particle size and degree of agglomeration increased by increase of collision frequency. Also, it was found from the XRD analyses and BET measurements that crystallite size and particle size decreased with elevating applied voltage. However, SMPS measurements and TEM observation revealed the increase of particle size and degree of agglomeration with increase of applied voltage. These results suggested that particle growth and agglomeration depend on overheating factor in chamber at the early stage and thermal coagulation in filtering system during powder formation until collection.

An Experimental Study on Optimal Condition of Aerodynamic Lens in the Modified ISPM (개선형 ISPM에서 공기역학적 렌즈의 최적조건에 대한 실험적 연구)

  • 임효재;차옥환;설용태
    • Journal of the Semiconductor & Display Technology
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    • v.3 no.2
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    • pp.1-4
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    • 2004
  • An experimental study was conducted on the optimal configuration and size of ADFL(Aerodynamic Focusing Lens) which used in modified ISPM(In-Situ Particle Monitoring). The particle counting efficiency has been known as a function of distance and size of ADFL, thus we varied these parameters to find out the optimum values. From a result of experiment, it was found that two lenses and 6mm space between them showed a maximum particle measuring efficiency. To apply this modified ISPM to semiconductor manufacturing field, we need more experiment about the pressure change, flow rate, and input particle size.

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Distribution and Behaviors of In-Situ Suspended Particulate Matters of Gwangyang Bay (광양만내의 현장 부유입자물질 분포와 거동)

  • Lee, Byoung-Kwan;Kim, Seok-Yun;Cho, Hyun-Man
    • Journal of Ocean Engineering and Technology
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    • v.24 no.1
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    • pp.99-105
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    • 2010
  • The concentration and size analysis of in-situ suspended particulate material were measured using an optical instrument, LISST-100, in the bottom layer at the three inlets of the Seomjin River Estuary, mouth of Gwangyang bay, and Gwangyang bay-side of the Namhae Bridge. In the Seomjin river estuary and mouth of Gwangyang bay-side of the Namhae Bridge, the in-situ mean grain size of the suspended material changed from a uni-modal distribution with a dominant peak at a coarse fraction to a bi-modal distribution with a secondary peak at the finer particles. Seomjin River. The interactions between suspended particulate concentration and beam attenuation coefficient of suspended particulate matters depended on the supply of finer and coarser particles in the mouth of Gwangyang Bay and Seomjin River. So, interactions reflected difference of the concentration, mean size and sorting of suspended particulate matters. The difference of interaction showed dynamic behaviors to the resuspension and deflocculation processes increased river discharge. This showed that it may be possible to use the interactions between the suspended particle concentration and beam attenuation coefficient to monitor the temporal and spatial distributions of in-situ particles.

Study of Incipient Soot Particles with Measuring Methodologies (입자 측정방법을 통한 초기 수트입자 연구)

  • Lee Eui Ju
    • Journal of the Korean Society of Visualization
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    • v.2 no.1
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    • pp.12-17
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    • 2004
  • The physical characteristics of soot near the soot inception point were investigated with various measurements. In-situ measurements of particle size and volume fraction were introduced based on time resolved laser-induced incandescence (TIRE-LII) and laser-induced ion mobility (LIIM). The one has more convenience and accuracy than conventional LII technique and the other works best for particle sizes of a few nanometers at high concentrations in a uniform concentration field. A complementary ex-situ measurement of particle size is nano differential mobility analyzer (Nano-DMA), which recently developed for measuring particle sizes between 2nm and 100nm and provides high-resolution size information for early soot. Particles will be also collected on transmission electron microscope (TEM) grids using rapid thermophoretic sampling and analyzed for morphology. These measurements will allow fresh and original insight into the characterizing soot inception process. The measured physical properties of incipient soot will clarify the controlling growth mechanism combined with chemical ones, and the dominant mechanism for soot modeling can be deduced from the information.

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Development and Performance Test of In-situ Particle Monitoring System using Ion-counter in Vacuum Environments (진공 환경내 실시간 입자 모니터링 시스템의 개발 및 성능평가)

  • Ahn Kang-Ho;Kim Yong-Min;Kwon Yong-Taek
    • Journal of the Semiconductor & Display Technology
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    • v.5 no.1 s.14
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    • pp.45-49
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    • 2006
  • In this paper, a new method that monitors the quantity of particles using ion-counter in vacuum environment is introduced. In-situ particle monitoring (ISPM) system is composed by Gerdien type ion-counter (house-made), DC power supply and electrometer. The ion-counter applied by positive voltage detects only positive charged particles. Therefore the particles to be detected should be in known charge state for further data analysis. ion-counter is installed at the exhaust line of process equipment where the pressure loss is structurally low. ISPM system performance has been verified with SMPS (Scanning Mobility Particle Sizer) system. The correlation coefficient is above 0.98 at the particle size range of $20{\sim}300nm$ in diameter with identified charge distribution under $0.1{\sim}10.0$ Torr.

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Generation and Size Control of Particle Beams at Low Pressures Using Aerodynamic Lenses (저압상태에서 공기역학적 렌즈를 이용한 입자 빔의 생성 및 크기 제어)

  • Bae, Gwi-Nam
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.23 no.10
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    • pp.1320-1326
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    • 1999
  • Since it is not possible to generate spatially uniform particle distribution at low pressures in which in-situ particle monitors(ISPMs) are normally operated, it is of interest to investigate the response of an ISPM to particle beams at low pressures. The purpose of this study is to develop technique that can control the size of particle beams. In this study, particle beams were generated at low pressures by using identical aerodynamic lenses, and their shape and size were visualized by collecting uniform sized methylene blue aerosol particles on a filter media. It was found that the size of particle beams depends on the number of lens, the distance between lenses, and the downstream distance from the final lens. The size of particle beams decreases with increasing distance between lenses, and increases with increasing downstream distance from the final lens. The experimental results obtained in this work will be used to investigate performance of an ISPM at low pressures.

Calculations of Optical Properties of Cloud Particles to Improve the Accuracy of Forward Scattering Probes for In-Situ Aircraft Cloud Measurements (항공기 구름 관측에 사용되는 전방산란 관측 기기의 정확도 향상을 위한 구름입자의 광학적 특성 계산)

  • Um, Junshik
    • Atmosphere
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    • v.30 no.1
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    • pp.75-89
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    • 2020
  • Current in-situ airborne probes that measure the sizes of ice crystals smaller than 50 ㎛ are based on the concept that the measured intensity of light scattered by a particle in the forward and/or backward direction can be converted to particle size. The relationship between particle size and scattered light used in forward scattering probes is based on Mie theory, which assumes the refractive index of particle is known and all particles are spherical. Not only are small crystals not spherical, but also there are a wide variety of non-spherical shapes. Although it is well known that the scattering properties of non-spherical ice crystals differ from those of spherical shapes, the impacts of non-sphericity on derived in-situ particle size distributions are unknown. Thus, precise relationships between the intensity of scattered light and particle size and shape are required, as based on accurate calculations of scattering properties of ice crystals. In this study, single-scattering properties of ice crystals smaller than 50 ㎛ are calculated at a wavelength of 0.55 ㎛ using a numerically exact method (i.e., discrete dipole approximation). For these calculations, hexagonal ice crystals with varying aspect ratios are used to represent the shapes of natural small ice crystals to determine the errors caused by non-spherical ice crystals measured by forward scattering probes. It is shown that the calculated errors in sizing nonspherical ice crystals are at least 13% and 26% in forward (4~12°) and backward (168~176°) directions, respectively, and maximum errors are up to 120% and 132%.