Measurements of Electron Energy Probability Functions in inductively coupled plasma with laser Thomson scattering

Seo, Byonghoon; You, S. J.; You, Guanhong; Kim, J H; Yoo, Yong Shim; Seong, Dong-Ook; Chang, Hong‐Young

doi:10.1088/1748-0221/7/01/c01049

Cited by 8 publications

(8 citation statements)

References 19 publications

(35 reference statements)

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“…An ICCD (Intensified charge coupled device) camera was mounted on the side of the monochromator and operated at doubled trigger signals (20 Hz) of the laser trigger (10 Hz) to extract background signals emitted by the plasma simultaneously. 17 The detected LIF signals and background emission signals were recorded and transferred to a computer for further data processing. The EEPF (Electron energy probability function) measurements were performed using an RF-compensated Langmuir probe.…”

Section: Methodsmentioning

confidence: 99%

Normal and abnormal evolution of argon metastable density in high-density plasmas

2015

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A controversial problem on the evolution of Ar metastable density as a function of electron density (increasing trend versus decreasing trend) was resolved by discovering the anomalous evolution of the argon metastable density with increasing electron density (discharge power), including both trends of the metastable density [Daltrini et al., Appl. Phys. Lett. 92, 061504 (2008)]. Later, by virtue of an adequate physical explanation based on a simple global model, both evolutions of the metastable density were comprehensively understood as part of the abnormal evolution occurring at low-and high-density regimes, respectively, and thus the physics behind the metastable evolution has seemed to be clearly disclosed. In this study, however, a remarkable result for the metastable density behavior with increasing electron density was observed: even in the same electron density regime, there are both normal and abnormal evolutions of metastable-state density with electron density depending on the measurement position: The metastable density increases with increasing electron density at a position far from the inductively coupled plasma antenna but decreases at a position close to the antenna. The effect of electron temperature, which is spatially nonuniform in the plasma, on the electron population and depopulation processes of Argon metastable atoms with increasing electron density is a clue to understanding the results. The calculated results of the global model, including multistep ionization for the argon metastable state and measured electron temperature, are in a good agreement with the experimental results. V C 2015 AIP Publishing LLC. [http://dx.

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Section: Methodsmentioning

confidence: 99%

Normal and abnormal evolution of argon metastable density in high-density plasmas

2015

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“…Since accurate diagnosis of these plasma parameters is important, it has been continually investigated by comparative studies. [2][3][4][5] Diagnosis using probes has often been employed because the types and methods of these diagnostics are easy to make, use, and utilize in both the laboratory and industry. The most famous and often used is the Langmuir probe.…”

Section: Introductionmentioning

confidence: 99%

“…6,7 Comparative studies have also been performed with other diagnostic methods such as Thomson scattering (TS) and optical emission spectroscopy, which means that the reliability of the probes has been investigated to a great extent. [2][3][4] Over the past few decades, many probes that use microwaves have also been operated in conjunction with Langmuir probes. The plasma parameters can be measured even if the probe is contaminated by dielectric materials during the process, so it can be applied to processing plasmas.…”

Section: Introductionmentioning

confidence: 99%

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Investigation of reliability of the cutoff probe by a comparison with Thomson scattering in high density processing plasmas

Seo

Kim

et al. 2017

Physics of Plasmas

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A "cutoff probe" uses microwaves to measure the electron density in a plasma. It is particularly attractive because it is easy to fabricate and use, its measurement is immune to surface contamination by dielectric materials, and it has a straightforward analysis to measure electron density in real time. In this work, we experimentally investigate the accuracy of the cutoff probe through a detailed comparison with Thomson scattering in a low temperature, high density processing plasma. The result shows that the electron density measured by the cutoff probe is lower than that by Thomson scattering and that the discrepancy of the two results becomes smaller as the gap between the two tips increases and/or the neutral gas pressure decreases. The underestimated electron density found by the cutoff probe can be explained by the influence of the probe holder, which becomes important as the pressure increases and the gap gets closer.

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“…The details for the alignment of optics and the data process are presented in the previous paper. 23 The temporal measurement of LRS light signal with the time resolution of 1 s was made by displaying 1 data point averaged over 10 laser shots, and its measurement was performed at the position of 10 cm below from the chamber cover (same height as that of pressure gauge). For theoretical investigation about our experimental result, the energy balance equations for neutrals and ions are solved simultaneously by coupling with the equations of relation between throughput and pressure difference 26 (Q ¼ dðPVÞ=dt; Q ¼ CDP, where V and Q are a chamber volume and a net throughput on the chamber volume V, and C is the conductance of the system for neutral gas).…”

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confidence: 99%

On anomalous temporal evolution of gas pressure in inductively coupled plasma

Seo

You

Kim

et al. 2013

Applied Physics Letters

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The temporal measurement of gas pressure in inductive coupled plasma revealed that there is an interesting anomalous evolution of gas pressure in the early stage of plasma ignition and extinction: a sudden gas pressure change and its relaxation of which time scales are about a few seconds and a few tens of second, respectively, were observed after plasma ignition and extinction. This phenomenon can be understood as a combined result between the neutral heating effect induced by plasma and the pressure relaxation effect for new gas temperature. The temporal measurement of gas temperature by laser Rayleigh scattering and the time dependant calculations for the neutral heating and pressure relaxation are in good agreement with our experimental results. This result and physics behind are expected to provide a new operational perspective of the recent plasma processes of which time is very short, such as a plasma enhanced atomic layer deposition/etching, a soft etch for disposal of residual by-products on wafer, and light oxidation process in semiconductor manufacturing.

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Measurements of Electron Energy Probability Functions in inductively coupled plasma with laser Thomson scattering

Cited by 8 publications

References 19 publications

Normal and abnormal evolution of argon metastable density in high-density plasmas

Normal and abnormal evolution of argon metastable density in high-density plasmas

Investigation of reliability of the cutoff probe by a comparison with Thomson scattering in high density processing plasmas

On anomalous temporal evolution of gas pressure in inductively coupled plasma

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