Examination of clean room aerosol particle composition by total reflection X-ray analysis and electron probe microanalysis

Ebert, Martin; Dahmen, J.; Hoffmann, P.; Ortner, Hugo M.

doi:10.1016/s0584-8547(96)01634-5

Cited by 20 publications

(6 citation statements)

References 6 publications

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“…The sampler was fixed at the northwest side, sufficiently far away from the tower framework to minimize sampling artifacts. For collecting particles, a glassy carbon substrate was chosen due to its extraordinary smooth surface allowing for a clear image-analytical separation of particles and background (Ebert et al, 1997). However, as the substrate is not sticky, a fraction of the particles might be re-entrained into the atmosphere during heavy gusts, though the Sigma-2 sampler minimizes the interior flow velocity.…”

Section: Sigma-2 Passive Sampler and Scanning Electron Microscopy (Sem)mentioning

confidence: 99%

Mass deposition fluxes of Saharan mineral dust to the tropical northeast Atlantic Ocean: an intercomparison of methods

et al. 2014

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Abstract. Mass deposition fluxes of mineral dust to the tropical northeast Atlantic Ocean were determined within this study. In the framework of SOPRAN (Surface Ocean Processes in the Anthropocene), the interaction between the atmosphere and the ocean in terms of material exchange were investigated at the Cape Verde atmospheric observatory (CVAO) on the island Sao Vicente for January 2009. Five different methods were applied to estimate the deposition flux, using different meteorological and physical measurements, remote sensing, and regional dust transport simulations. The set of observations comprises micrometeorological measurements with an ultra-sonic anemometer and profile measurements using 2-D anemometers at two different heights, and microphysical measurements of the sizeresolved mass concentrations of mineral dust. In addition, the total mass concentration of mineral dust was derived from absorption photometer observations and passive sampling. The regional dust model COSMO-MUSCAT was used for simulations of dust emission and transport, including dry and wet deposition processes. This model was used as it describes the AOD's and mass concentrations realistic compared to the measurements and because it was run for the time period of the measurements. The four observation-based methods yield a monthly average deposition flux of mineral dust of 12-29 ng m −2 s −1 . The simulation results come close to the upper range of the measurements with an average value of 47 ng m −2 s −1 . It is shown that the mass deposition flux of mineral dust obtained by the combination of micrometeorological (ultra-sonic anemometer) and microphysical measurements (particle mass size distribution of mineral dust) is difficult to compare to modeled mass deposition fluxes when the mineral dust is inhomogeneously distributed over the investigated area.

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Section: Sigma-2 Passive Sampler and Scanning Electron Microscopy (Sem)mentioning

confidence: 99%

Mass deposition fluxes of Saharan mineral dust to the tropical northeast Atlantic Ocean: an intercomparison of methods

et al. 2014

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“…Cr, Zn, Cu, Ni, W, Ti, Al, Mg, and Na. 26 Considering the bulk densities of these material at 20 C, representative Figure 6. Effect of Stokes drag with slip correction, Brownian diffusion, and gravity on particle deposition velocity, for an inverted flat plate in a parallel airflow, without considering thermophoresis.…”

Section: Resultsmentioning

confidence: 99%

“…Cr, Zn, Cu, Ni, W, Ti, Al, Mg, and Na. 26 Considering the bulk densities of these material at 20 C, representative particle densities were determined as q p ¼ 1, 5, 9, and 19 g/cm 3 . In order to observe the effect of particle density only, the particle thermal conductivity was fixed to be k p ¼ 0.17 W/mÁK.…”

Section: Resultsmentioning

confidence: 99%

Numerical Investigation of Thermophoretic Effect on Particulate Contamination of an Inverted Flat Surface in a Parallel Airflow

Kim

Lee

Yook

2011

J. Electrochem. Soc.

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Thermophoretic effect on particle deposition velocity onto an inverted flat surface was numerically investigated, by employing the Statistical Lagrangian Particle Tracking (SLPT) model. The SLPT model was verified to be correct, when the numerically obtained particle deposition velocities were compared with the theoretically predicted particle deposition velocities, with and without considering thermophoresis. Temperature difference between flat surface and ambient air, particle density, and airflow velocity were found to affect the particle deposition velocity onto the inverted flat surface under the influence of thermophoresis. Thermal conductivity ratio between air and particle, however, was found to be insignificant in affecting the particle deposition velocity onto the inverted flat surface. Particulate contamination of the inverted critical surface was estimated to be greatly reduced by heating the surface. On the other hand, the face-down critical surface was anticipated to be contaminated by particles when the surface temperature was lower than the ambient temperature, even with the scheme of inverted orientation.The control of particulate contamination in semiconductor manufacturing becomes more important with decreasing feature size. According to the International Technology Roadmap for Semiconductors (ITRS 2010), the feature size is expected to shrink down to 27 nm by 2014, which implies that even nanoparticles need to be considered as the possible contamination sources. In addition, photomasks used for the Extreme Ultraviolet Lithography (EUVL), which is thought of as the prominent candidate for the next lithography technology generation to manufacture the patterns of 32 nm or smaller, cannot be protected by pellicles against particulate contamination. 1,2Mounting wafers or photomasks with their critical surfaces facing-down is one of the schemes to reduce the level of particulate contamination, since particles can drift away from the critical surface due to the gravitational settling. 3-6 External forces other than the gravity, for instance electrophoresis or thermophoresis, can be applied to repel the particles away from the face-down critical surface. The electrophoresis, however, may be counterproductive depending on the polarity of particles. 3,5 On the other hand, thermophoresis, which is the phenomenon wherein aerosol particles drift in the direction of decreasing temperature, forces particles to move in one direction and therefore can be useful for pushing the particles away from the critical surface, if an appropriate temperature gradient is established.Particle deposition velocity is defined as the ratio of the particle flux onto a surface to the number concentration of aerosol particles above that surface, and thus can be used to assess the possibility of the critical surface to be contaminated by particles. Many studies have been performed to investigate the particle deposition velocity onto free standing face-up wafers situated perpendicular to the airflow, by assuming the vertical airflo...

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“…All aerosol samples were collected on pure carbon adhesive 125 substrates (Spectro Tabs, Plano GmbH, Wetzlar, Germany) mounted on standard SEM aluminum stubs. Pure carbon substrate was chosen because of its excellent smooth surface resulting in a clear image-analytical separation of particles and background (Ebert et al, 1997). All adhesive samples were stored in standard SEM storage boxes (Ted Pella Inc., Redding, CA, USA) in dry conditions at room temperature.…”

Section: Sampling Techniquesmentioning

confidence: 99%

Insights into the single particle composition, size, mixing state and aspect ratio of freshly emitted mineral dust from field measurements in the Moroccan Sahara using electron microscopy

Pańta

Kandler

Alastuey

et al. 2022

Preprint

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Abstract. The chemical and morphological properties of mineral dust aerosols emitted by wind erosion from arid and semi-arid regions influence climate, ocean and land ecosystems, air quality, and multiple socio-economic sectors. However, there is an incomplete understanding of the emitted dust particle size distribution (PSD) in terms of its constituent minerals that typically result from the fragmentation of soil aggregates during wind erosion. The emitted dust PSD affects the duration of particle transport and thus each mineral’s global distribution, along with its specific effect upon climate. This lack of understanding is largely due to the scarcity of relevant in situ measurements in dust sources. To advance our understanding of the physicochemical properties of the emitted dust PSD, we present insights into the elemental composition and morphology of individual dust particles collected during the FRontiers in dust minerAloGical coMposition and its Effects upoN climaTe (FRAGMENT) field campaign in the Moroccan Sahara in September 2019. We analyzed more than 300,000 freshly emitted individual particles by performing offline analysis in the laboratory using Scanning Electron Microscopy (SEM) coupled with Energy-Dispersive X-ray Spectrometry (EDX). Eight major particle-type classes were identified where clay minerals make up the majority of the analyzed particles by number, with carbonates and quartz contributing to a lesser extent. We provide an exhaustive analysis of the size distribution and potential mixing state of different particle types, focusing largely on iron-rich (Fe-oxi/hydroxides) and feldspar particles, which are key to the effects of dust upon radiation and clouds. Nearly pure or externally mixed Fe-oxi/hydroxides are present only in diameters smaller than 2 µm and mainly below 1 µm. Fe-oxi/hydroxides tend to be increasingly internally mixed with other minerals, especially clays, as particle size increases, i.e., the volume fraction of Fe-oxi/hydroxides in aggregates decreases with particle size. Pure (externally-mixed) feldspar grains represented 3.7 % of all the particles, of which we estimated about a quarter to be K-feldspar. The externally-mixed total feldspar and K-feldspar abundances are relatively invariant with particle size, in contrast to the increasing abundance of feldspar-like (internally-mixed) aggregates with particle size. We also found that overall the median aspect ratio is rather constant across particle size and mineral groups, although we obtain slightly higher aspect ratios for internally-mixed particles. The detailed information on the composition of freshly emitted individual dust particles along with the quantitative analysis of their mixing state presented here can be used to constrain climate models including mineral species in their representation of the dust cycle.

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Examination of clean room aerosol particle composition by total reflection X-ray analysis and electron probe microanalysis

Cited by 20 publications

References 6 publications

Mass deposition fluxes of Saharan mineral dust to the tropical northeast Atlantic Ocean: an intercomparison of methods

Mass deposition fluxes of Saharan mineral dust to the tropical northeast Atlantic Ocean: an intercomparison of methods

Numerical Investigation of Thermophoretic Effect on Particulate Contamination of an Inverted Flat Surface in a Parallel Airflow

Insights into the single particle composition, size, mixing state and aspect ratio of freshly emitted mineral dust from field measurements in the Moroccan Sahara using electron microscopy

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