Numerical study of extreme-ultra-violet generated plasmas in hydrogen

Astakhov, Dmitry

doi:10.3990/1.9789036541114

Cited by 7 publications

(10 citation statements)

References 108 publications

(194 reference statements)

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“…Where ion fluxes, ion energy distributions functions (IEDFs), and radicals describe to a large extent the interaction of plasma with plasma-facing surfaces (subject of Section 3), two quantities that are predominantly important in describing the "ecosystem" in the bulk of the pulsed plasma are the density and the temperature of the free electrons. Note that, although negative H − ions may be formed as well in hydrogen plasmas, it was derived by Astakhov et al [12]-while using cross sections for dissociative electron attachment of highly vibrationally excited H 2 * (e.g., υ = 4) [13] and for direct excitation to such states [14]-that the densities of H − ions are negligible in the current case.…”

Section: Key Parameters Of Euv-induced Plasmamentioning

confidence: 75%

“…Although this technique may be able to probe electrons in the here relevant density range, Van de Velden et al [33] concluded that it was not feasible to apply probes to EUV-induced plasmas, with the main reason being that the photo-electric currents obscured the measurements of the I-V curves. Later, Astakhov et al came to a similar conclusion by experimental work that was analyzed while using different probe theories and compared to numerical simulations [12,22].…”

Section: Recent Experimental Work On Euv-induced Bulk Plasmasmentioning

confidence: 77%

“…Upon collision, these electrons may ionize the H 2 background gas even further by electron impact ionization. Comparable to photoionization (Equations (6)-(8)), the three electron impact ionization processes playing a role in hydrogen are single ionization (see Equation (10)), dissociative ionization (see Equation (11)), and double ionization (Equation (12)…”

Section: Electron Impact Ionizationmentioning

confidence: 99%

“…Carbon removal by EUV-induced plasmas has been numerically and experimentally investigated [12,91] [64,91]. The carbon samples were negatively biased from 0-200 V in both of the studies.…”

Section: Carbon Removalmentioning

confidence: 99%

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EUV-Induced Plasma: A Peculiar Phenomenon of a Modern Lithographic Technology

et al. 2019

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After a long period of relatively low interest, science related to effects in the Extreme Ultraviolet (EUV) spectrum range experienced an explosive boom of publications in the last decades. A new application of EUV in lithography was the reason for such a growth. Naturally, an intensive development in such area produces a snowball effect of relatively uncharted phenomena. EUV-induced plasma is one of those. While being produced in the volume of a rarefied gas, it has a direct impact onto optical surfaces and construction materials of lithography machines, and thus has not only scientific peculiarity, but it is also of major interest for the technological application. The current article provides an overview of the existing knowledge regarding EUV-induced plasma characteristics. It describes common, as well as distinguishing, features of it in comparison with other plasmas and discusses its interaction with solid materials. This article will also identify the gaps in the existing knowledge and it will propose ways to bridge them.

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Section: Key Parameters Of Euv-induced Plasmamentioning

confidence: 75%

Section: Recent Experimental Work On Euv-induced Bulk Plasmasmentioning

confidence: 77%

Section: Electron Impact Ionizationmentioning

confidence: 99%

“…Carbon removal by EUV-induced plasmas has been numerically and experimentally investigated [12,91] [64,91]. The carbon samples were negatively biased from 0-200 V in both of the studies.…”

Section: Carbon Removalmentioning

confidence: 99%

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EUV-Induced Plasma: A Peculiar Phenomenon of a Modern Lithographic Technology

et al. 2019

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“…The processes that influence the reflectivity are actively investigated in multiple studies. 5,[7][8][9][10][11][12][13][14][15] The interaction between EUV induced plasma and adjacent surfaces can have beneficial effects such as the removal of contamination by EUV-reactive ion sputtering. 5 Negative effects include the degradation of multilayer coatings due to delamination leading to the formation of blisters.…”

Section: Introductionmentioning

confidence: 99%

Ion energy distributions in highly transient EUV induced plasma in hydrogen

Ven

Reefman

Meijere

et al. 2018

Journal of Applied Physics

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This work reports on the measurements of ion flux composition and ion energy distribution functions (IEDFs) at surfaces in contact with hydrogen plasmas induced by extreme ultraviolet (EUV) radiation. This special type of plasma is gaining interest from industries because of its appearance in extreme ultraviolet lithography tools, where it affects exposed surfaces. The studied plasma is induced in 5 Pa hydrogen gas by irradiating the gas with short (30 ns) pulses of EUV radiation (k ¼ 10-20 nm). Due to the low duty cycle (10-4), the plasma is highly transient. The composition and IEDF are measured using an energy resolved ion mass spectrometer. The total ion flux consists of H þ ; H þ 2 , and H þ 3. H þ 3 is the dominant ion as a result of the efficient conversion of H þ 2 to H þ 3 upon collision with background hydrogen molecules. The IEDFs of H þ 2 and H þ 3 appear similar, showing a broad distribution with a cutoff energy at approximately 8 eV. In contrast, the IEDF of H þ shows an energetic tail up to 18 eV. Most probably, the ions in this tail gain their energy during their creation process by photoionization and dissociative electron impact ionization.

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Time-resolved ion energy distribution functions in the afterglow of an EUV-induced plasma

Beckers

Ven

Banine

2019

Applied Physics Letters

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Since the introduction of extreme ultraviolet (EUV) lithography (EUVL), the inevitable presence of EUV-induced plasmas inside the lithography tools impacts the operation of EUV optical components. EUV-induced plasmas are created everywhere in the optical path due to the ionizing interaction between the high energy (92 eV) EUV photons and the tools' background gas, which typically is hydrogen gas at a pressure of 1–10 Pa. From a physical point of view, the main impact of the plasma is due to the presence of ions that imping the plasma-facing surfaces. Experimental research into the fluence and energy distribution functions (IEDFs) of ions from EUV-induced plasmas has been limited to time-averaged measurements. In this Letter, we present time-resolved measurements of IEDFs for H+, H2+, and H3+ ions from an EUV-induced plasma in pure hydrogen gas. To this end, an electrostatic quadrupole plasma (EQP) analyzer has been used. The measurements pinpointed momentary fluxes up to three orders of magnitude higher than earlier reported average ion fluxes. In addition, the mean ion energy was unexpectedly found to remain elevated up to 50 μs after the gas had been irradiated with EUV photons. Also, it was shown that the EQP detects H2+ ions on time scales much larger than expected. The presented results are valuable not only for the understanding of elementary processes regarding EUV-induced plasmas interacting with surfaces but also for simulating and predicting the impact of EUV-induced plasma on the lifetime and stability of optical components in EUVL.

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Numerical study of extreme-ultra-violet generated plasmas in hydrogen

Cited by 7 publications

References 108 publications

EUV-Induced Plasma: A Peculiar Phenomenon of a Modern Lithographic Technology

EUV-Induced Plasma: A Peculiar Phenomenon of a Modern Lithographic Technology

Ion energy distributions in highly transient EUV induced plasma in hydrogen

Time-resolved ion energy distribution functions in the afterglow of an EUV-induced plasma

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