Advanced particle contamination control in EUV scanners

Kerkhof, Mark van de; Empel, Tjarko van; Lercel, Michael J.; Smeets, Christophe; Wetering, Ferdi van de; Nikipelov, Andrey; Cloin, Christian; Yakunin, A. M.; Banine, VY Vadim

doi:10.1117/12.2514874

Cited by 28 publications

(24 citation statements)

References 2 publications

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“…While the electrical field is negligible in the afterglow, during the transient phase it may reach values of E s ð0Þ ∼ 100 kV∕m, as the electron energies may be above T e > 10 eV (and λ D ≅ 0.5 mm). 3 For a pulsed plasma, the plasma cools down and diffuses out during the afterglow, but if the pulse period is shorter than the decay time, the next pulse will be a combination of the residual afterglow plasma and the newly created plasma. These two contributions have independent electron energy distributions.…”

Section: Plasma Equationsmentioning

confidence: 99%

“…Even with the outstanding imaging and overlay capability of the current EUV scanners, 2 device output and yield can still be affected adversely by other factors, such as molecular or particulate contamination on critical imaging surfaces. 3 Also, high source power and mirror reflectivity must be secured over the full scanner lifetime. Theoretically, it would be ideal to do EUV lithography in vacuum conditions since EUV photons are absorbed by any medium.…”

Section: Introductionmentioning

confidence: 99%

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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: Plasma Equationsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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

Kerkhof

Yakunin

Astakhov

et al. 2021

J. Micro/Nanopattern. Mats. Metro.

View full text Add to dashboard Cite

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“…Even with the outstanding imaging and overlay capability of the current EUV scanners [1], device output and yield can still be affected adversely by other factors, such as molecular or particulate contamination on critical imaging surfaces [2]. The EUV scanner operates in near-vacuum (~1-10 Pa) but may have relatively high partial pressures of hydrocarbons around the wafer stage, as a result of outgassing of organic resist components [3]. As a consequence, integrated sensors and mirrors may get contaminated, which may result in drifts in measured dose, position or focus.…”

Section: Introductionmentioning

confidence: 99%

Miniature plasma source for in situ extreme ultraviolet lithographic scanner cleaning

Kerkhof

Osorio

Krivtsun

et al. 2022

Journal of Vacuum Science &Amp; Technology B

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Extreme ultraviolet (EUV) lithography is the technology of choice for high-volume manufacturing of sub-10nm lithography. One of the challenges is to enable in situ cleaning of functional surfaces, such as sensors, fiducials and interferometer mirrors, without opening the scanner tool. Thermally created hydrogen radicals have been successfully used for this purpose. These sources have limited cleaning speed and a relatively high thermal load to the surface being cleaned. Here, we present an alternative plasma-based technique to simultaneously create hydrogen radicals and hydrogen ions. This results in significantly improved cleaning speed while simultaneously reducing the overall thermal load. As an additional benefit, this plasma source has a minimized and flexible building volume to allow easy integration into various locations in the EUV lithographic scanner.

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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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Advanced particle contamination control in EUV scanners

Cited by 28 publications

References 2 publications

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

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

Miniature plasma source for in situ extreme ultraviolet lithographic scanner cleaning

Particle contamination control by application of plasma

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