Radical probe system for <i>in situ</i> measurements of radical densities of hydrogen, oxygen, and nitrogen

Qerimi, Dren; Shchelkanov, Ivan; Panici, Gianluca A.; Jain, Arihant; Wagner, J. Richard; Ruzic, D. N.

doi:10.1116/6.0000786

Cited by 7 publications

(5 citation statements)

References 35 publications

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“…These values and trends are in good agreement with previous studies. [ 45–47 ] As the electron density increases from 10 9 to 3.5 × 10 10 cm −3 at a pressure of 20 mTorr, the H density increases, and the H 2 density tends to decrease as shown in Figure 6b. This is because the electron temperature is constant, and under fixed electron temperature and gas pressure conditions, the reaction rate is proportional to the electron density.…”

Section: Resultsmentioning

confidence: 94%

Evaluation of H₂ Plasma‐Induced Damage in Materials for EUV Lithography

Choe,

Choi,

Kim

et al. 2023

Adv Materials Inter

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Ultrafine semiconductor fabrication by lithography has undergone a significant transition from deep ultraviolet (DUV) to extreme ultraviolet (EUV) processes, which presents new challenges. Specifically, the damage caused to components utilized in an EUV system, such as multilayer mirrors, reticles, and pellicles within lithography equipment, owing to EUV‐induced H2 plasma, is a critical issue that directly affects the process yield and equipment lifespan. To address these issues, it is crucial to establish an environment similar to that of EUV‐induced plasma and develop a method to evaluate the resulting damage. Accordingly, an evaluation method is developed for assessing the material damage caused by hydrogen radicals and ions in inductively coupled H2 plasma. In these systems, the electron density ranged from 5 × 108 to 3.5 × 1010 cm−3, the electron temperature ranged from 1 to 4 eV, and the ion energy ranged from several to tens of eV; these conditions closely align with the environment of an EUV‐induced H2 plasma. The damage to Mo2C, a potential EUV pellicle material, is quantitatively analyzed by measuring the fraction of the pore area and examining the chemical characteristics after exposing the samples to various plasma conditions, including electron density, gas pressure, and exposure time.

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Section: Resultsmentioning

confidence: 94%

Evaluation of H₂ Plasma‐Induced Damage in Materials for EUV Lithography

Choe,

Choi,

Kim

et al. 2023

Adv Materials Inter

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“…The variation of current against applied voltage provides the necessary information to extract the electron density and temperature in the plasma. Alternatively, for probing neutral particles, a thermocouple can be coated with particular metals that the neutral particles are highly reactive with [19]. This approach has been shown as especially useful with highly electronegative radicals.…”

Section: Alternative Diagnostics and Limitationsmentioning

confidence: 99%

“…This approach has been shown as especially useful with highly electronegative radicals. Reactions between the particles and metal coating generate heat near the thermocouple tip such that temperature readings can be used to extract particle densities [19]. Neutral xenon particles do not interact via the Coulomb interaction as ions do, nor do they readily recombine as radicals and reactive gases do.…”

Section: Alternative Diagnostics and Limitationsmentioning

confidence: 99%

Two-Photon Absorption Laser Induced Fluorescence (TALIF) Of Neutral Xenon In A Hall Effect Thruster Plasma

Wegner

Thompson

Williams

et al. 2021

AIAA Propulsion and Energy 2021 Forum

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TWO-PHOTON ABSORPTION LASER INDUCED FLUORESCENCE (TALIF) OF NEUTRAL XENON IN A HALL EFFECT THRUSTER PLASMA This work presents measurements of ground state neutral xenon in the plume of a 1.5 kW Hall Effect thruster (HET) using two-photon absorption laser induced fluorescence (TALIF).Neutral xenon particles in the thruster plasma play an important role in ionization processes, overall energy conversion, and life-limiting interactions with surrounding wall materials in the thruster. Therefore, a detailed understanding of the neutral particle dynamics within the plume is desired. The TALIF diagnostic technique allows for laser induced excitation of xenon from its ground state using commercially available laser systems at accessible ultraviolet wavelengths (~222 nm). The signal collected from fluorescence of the excited atoms can be used to determine the local neutral density. We present a demonstration of TALIF first in a barium oxide (BaO) hollow cathode plume at varying radial positions, then in an HET plume at varying axial positions using fiber coupled collection optics with a spatial resolution of 3.14 mm 2 . The detection limit of the TALIF measurement system 2.1 cm downstream of the thruster face was estimated to be 8 x 10 17 m -3 as determined by comparison to a known reference signal. The ability to analyze ionization and thermal characteristics using these results is also discussed.

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“…Instead of only one thermocouple, this type of catalytic probe consists of two heat sensors coated with two different materials, one of which promotes recombination of hydrogen radicals while the other one does not. If these two heat sensors receive the same background heat loads from the plasma, it is possible to extract the recombination heat load by differentiating the individual heat loads of two sensors [22,25]. Therefore, this type of radical probe may become a relatively simple alternative to TALIF to measure the hydrogen radical density for cascaded arc sources.…”

Section: Introductionmentioning

confidence: 99%

“…This problem may become very serious for a cascaded arc source, which is known to produce a range of heat loads, such as through gas and light, in addition to the plasma one [23,24]. To solve this problem, dual-sensor catalytic probes have been recently designed and demonstrated for high hydrogen radical fluxes [22,25]. Instead of only one thermocouple, this type of catalytic probe consists of two heat sensors coated with two different materials, one of which promotes recombination of hydrogen radicals while the other one does not.…”

Section: Introductionmentioning

confidence: 99%

Application of a dual-thermopile radical probe to expanding hydrogen plasmas

Wang

Horst

Kampen

et al. 2022

Plasma Sources Sci. Technol.

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We compare the performance of a hydrogen radical probe to historic data determined via Two-Photon Absorption Laser Induced Fluorescence (TALIF) using a comparable cascaded arc source under similar operating conditions. This probe has dual heat flux sensors (DHFS) each coated with materials with different catalytic properties for hydrogen atoms. In the ideal situation, the hydrogen radical flux can be deduced based on the difference between the heat loads measured by these two sensors. The influence of DHFS temperature on the performance was also assessed. The experimental results showed measurement errors of <10% could be obtained regardless of the probe temperature during plasma exposures. To convert heat fluxes into atomic fluxes, we calibrated the difference of the recombination coefficients using a vacuum ultraviolet (VUV) absorption technique, which is more reliable than modeled values based on assumptions or scattered values reported in literature. As a result, we measured the hydrogen plasma and radical parameters at various settings using both a double Langmuir probe and the DHFS. The typical atom flux in the 1022 m-2s-1 range was in good agreement with those obtained using optical techniques. We also observed that the ion and atom fluxes are both sensitive to the background gas pressure. These findings validate application of the DHFS to the cascaded arc source, and could pave the way for optimization of the source performance in the plasma material processing experiments.

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Radical probe system for in situ measurements of radical densities of hydrogen, oxygen, and nitrogen

Abstract: The current state-of-the-art methods to identify presence of radical species in vacuum chambers are optical methods, which suffer from the lack of spatial resolution and require expensive optical equipment. In this study Center for Plasma Material Interactions (CPMI)

Cited by 7 publications

References 35 publications

Evaluation of H₂ Plasma‐Induced Damage in Materials for EUV Lithography

Evaluation of H₂ Plasma‐Induced Damage in Materials for EUV Lithography

Two-Photon Absorption Laser Induced Fluorescence (TALIF) Of Neutral Xenon In A Hall Effect Thruster Plasma

Application of a dual-thermopile radical probe to expanding hydrogen plasmas

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Radical probe system for in situ measurements of radical densities of hydrogen, oxygen, and nitrogen

Abstract: The current state-of-the-art methods to identify presence of radical species in vacuum chambers are optical methods, which suffer from the lack of spatial resolution and require expensive optical equipment. In this study Center for Plasma Material Interactions (CPMI)

Cited by 7 publications

References 35 publications

Evaluation of H2 Plasma‐Induced Damage in Materials for EUV Lithography

Evaluation of H2 Plasma‐Induced Damage in Materials for EUV Lithography

Two-Photon Absorption Laser Induced Fluorescence (TALIF) Of Neutral Xenon In A Hall Effect Thruster Plasma

Application of a dual-thermopile radical probe to expanding hydrogen plasmas

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Evaluation of H₂ Plasma‐Induced Damage in Materials for EUV Lithography

Evaluation of H₂ Plasma‐Induced Damage in Materials for EUV Lithography