Energy distribution functions for ions from pulsed EUV-induced plasmas in low pressure N2-diluted H2 gas

Beckers, JL Jozef; Ven, T.H.M. van de; Meijere, C. A. de; Horst, R. M. van der; Kampen, M. van; Banine, VY Vadim

doi:10.1063/1.5091825

Cited by 13 publications

(10 citation statements)

References 29 publications

(32 reference statements)

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“…Earlier investigations, using isolated pulses, showed that trace amounts of N 2 might indeed affect the plasma composition and chemistry but do not change the ion energy distribution function (IEDF) of the hydrogen ions significantly. 60 This was confirmed recently on an LPP testrig for regular 50-kHz multipulse mode of operation. No measurable difference in IEDF was observed for an addition of 10 −2 Pa of N 2 level in 5 to 10 Pa H 2 , as shown in Fig.…”

Section: Gas Puritysupporting

confidence: 55%

“…The change in plasma composition might also change the plasma characteristics, as these heavier ions would diffuse out more slowly and would thus show more build-up over pulses. Earlier investigations, using isolated pulses, showed that trace amounts of N2 might indeed affect the plasma composition and chemistry, but do not change the IEDF of the hydrogen ions significantly 59 . This was confirmed recently on a LPP testrig for regular 50 kHz multi-pulse mode of operation.…”

Section: Gas Puritymentioning

confidence: 97%

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EUV-induced hydrogen plasma: pulsed mode operation and confinement in scanner

Kerkhof

Yakunin

Astakhov

et al. 2021

J. Micro/Nanopattern. Mats. Metro.

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In recent years, EUV lithography scanner systems have entered high-volume manufacturing for state-of-the-art integrated circuits, with critical dimensions down to 10 nm. This technology uses 13.5-nm EUV radiation, which is shaped and transmitted through a near-vacuum H 2 background gas. This gas is excited into a low-density H 2 plasma by the EUV radiation, as generated in pulsed mode operation by the laser-produced plasma in the EUV source. Thus, in the confinement created by the walls and mirrors within the scanner system, a reductive plasma environment is created that must be understood in detail to maximize mirror transmission over the lifetime and to minimize molecular and particle contamination in the scanner. In addition to the irradiated mirrors, reticle, and wafer, the plasma and radical load to the surrounding construction materials also must be considered. We provide an overview of the EUV-induced plasma in the scanner context. Special attention is given to the plasma parameters in a confined geometry, such as that found in the scanner area near the reticle. It is shown that plasma confinement and resulting contributions from secondary electron emission delay the formation of the plasma sheath and thereby reduce the peak ion energies to below the sputtering threshold for mirrors and construction materials. Furthermore, for a confined pulsed plasma with a pulse period shorter than the decay time of the plasma, the plasma consists of a quasi-steady-state cold background plasma and periodic transient peaks in ion energy and ion flux. In terms of modeling, this means that no assumptions can be made on the electron distribution functions and a (Monte-Carlo) particle-in-cell (PIC) model is needed. We present an extension of the PIC model approach to complex three-dimensional geometries and to multiple pulses using a hybrid PIC-diffusion approach. Also, the translation of these specific plasma parameters to off-line setups and the aspects that must be included to make a meaningful translation from off-line laboratory EUV setups to the scanner plasma are discussed. © The Authors. Published by SPIE under a Creative Commons Attribution 4.0 Unported License. Distribution or reproduction of this work in whole or in part requires full attribution of the original publication, including its DOI.

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Section: Gas Puritysupporting

confidence: 55%

Section: Gas Puritymentioning

confidence: 97%

EUV-induced hydrogen plasma: pulsed mode operation and confinement in scanner

Kerkhof

Yakunin

Astakhov

et al. 2021

J. Micro/Nanopattern. Mats. Metro.

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“…Of main importance in the governing plasma dynamics are the (photo-and electron-impact) ionization cross sections, which impact the maximum plasma density, the ion mass of the specific gas, which impacts the rate of plasma expansion and decay and the possibility to excite specific molecular and/or atomic energy levels. Very recently, EUV-induced plasmas in N 2 -diluted H 2 gas have been studied [63]. From that study, it was concluded that the addition of even a small amount of N 2 (in the order of 0.1%) to H 2 resulted in a significant alteration of the ionic balance of the system and a rich chemistry producing NH-containing ions.…”

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confidence: 99%

“…However, the addition of small amounts of other gases can have an important influence on the composition of the EUV-induced plasma and it might significantly alter plasma chemistry and plasma physical processes, and hence representing real scanner conditions more accurately [62]. Although the first explorative study on N 2 -dilution of EUV-induced plasmas in H 2 has recently been published [63], there remains a strong demand from industry to understand the effect of other gases/vapors (e.g., H 2 O, O 2 , and N 2 ) on the whole model of EUV-induced plasma dynamics.…”

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confidence: 99%

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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“…Over the past decade, EUV-induced plasmas have been diagnosed extensively 1 , not only experimentally by monitoring dynamics of electrons [2][3][4][5][6] and ions [7][8][9] , but also by means of numerical simulations 10,11 . The interaction of those plasmas with contamination has been recently pinpointed as key by van de Kerkhof et al 12 .…”

Section: Introductionmentioning

confidence: 99%

Particle contamination control by application of plasma

Beckers

Minderhout

Blom³

et al. 2020

Extreme Ultraviolet (EUV) Lithography XI

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Energy distribution functions for ions from pulsed EUV-induced plasmas in low pressure N2-diluted H2 gas

Abstract: Energy distribution functions for ions from pulsed EUV-induced plasmas in low pressure N2-diluted H2 gas. Applied Physics Letters, 114(13), [133502].

Cited by 13 publications

References 29 publications

EUV-induced hydrogen plasma: pulsed mode operation and confinement in scanner

EUV-induced hydrogen plasma: pulsed mode operation and confinement in scanner

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

Particle contamination control by application of plasma

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