Scaling of laser produced plasma UTA emission down to 3 nm for next generation lithography and short wavelength imaging

Li, Bowen; Endo, Akira; Ôtsuka, Takeshi; O’Gorman, Colm; Cummins, Thomas; Donnelly, T.; Kilbane, Deirdre; Jiang, Weihua; Higashiguchi, Takeshi; Yugami, Noboru; Dunne, Padraig; O'Sullivan, Gerry

doi:10.1117/12.892513

Cited by 7 publications

(1 citation statement)

References 25 publications

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“…In contrast to the situation for Gd, a significant number of publications on DR processes have been published for tungsten [9][10][11][12][13][14][15][16][17][18][19][20][21][22][23][24]. In all reported studies of gadolinium and tungsten plasmas, their emission is dominated by Ag-and Pd-like lines, that is, the spectra resulting from ions with either a closed outermost subshell (Pd-like) or a configuration with a single electron outside a closed subshell (Ag-like), where the emission is not spread among many transitions [23][24][25][26][27][28]. Recently, Safronova and co-workers studied the DR rate coefficients for Pd-like W [20].…”

Section: Introductionmentioning

confidence: 99%

Dielectronic recombination of Rh-like Gd and W

O’Sullivan

et al. 2012

Phys. Rev. A

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Ab initio calculations of dielectronic recombination rate coefficients of Rh-like gadolinium and tungsten have been performed. Energy levels, radiative transition probabilities, and autoionization rates of Pd-like gadolinium and tungsten for [Zn]4p 6 4d 8 4fnl, [Zn]4p 6 4d 8 5l nl, [Zn]4p 6 4d 8 6l nl and [Zn]4p 5 4d 10 nl, [Zn]4p 5 4d 9 4fnl, [Zn]4p 5 4d 9 5l nl, [Zn]4p 5 4d 9 6l nl (n 18) complexes were calculated using the flexible atomic code. The contributions from resonant and nonresonant radiative stabilizing transitions to the total rate coefficients are discussed. Results show that the contributions from nonresonant radiative stabilizing transitions are significantly enchanced for W when compared with Gd as a result of lowering of energy levels relative to the ionization limit. In addition, the widely used Burgess-Merts semiempirical formula may underestimate the dielectronic recombination rate coefficients in the temperature regions of interest. The present calculated rate coefficients are fitted to a semiemperical formula. The data obtained are expected to be useful for modelling plasmas both for extreme ultraviolet lithography source development and for fusion applications.

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Section: Introductionmentioning

confidence: 99%

Dielectronic recombination of Rh-like Gd and W

O’Sullivan

et al. 2012

Phys. Rev. A

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Feasibility study of broadband efficient “water window” source

Higashiguchi¹,

Ôtsuka²,

Yugami³

et al. 2012

Applied Physics Letters

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We demonstrate a table-top broadband emission water window source based on laser-produced high-Z plasmas. Resonance emission from multiply charged ions merges to produce intense unresolved transition arrays (UTAs) in the 2–4 nm region, extending below the carbon K edge (4.37 nm). Arrays resulting from n=4-n=4 transitions are overlaid with n=4-n=5 emission and shift to shorter wavelength with increasing atomic number. An outline of a microscope design for single-shot live cell imaging is proposed based on a bismuth plasma UTA source, coupled to multilayer mirror optics.

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Investigation of Gd and Tb plasmas for beyond extreme ultraviolet lithography based on multilayer mirror performance

Ôtsuka

Higashiguchi

et al. 2012

Applied Physics Letters

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Recent work on multilayer mirror development for beyond extreme ultraviolet lithography indicates that their optimum reflectivity occurs at either 6.63 nm or 6.66 nm which may be too short a wavelength for Gd-based plasma sources. Calculations performed for Tb12+ to Tb28+ ions show that if the mirror reflectivity is fixed at one of these values, Tb may be a better source, though Gd is capable of providing greater intensity if the full reflection curve of the mirrors is exploited. Theoretical simulation shows that the Tb emission peaks close to 6.51 nm at an optimum electron temperature close to 120 eV.

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Scaling of laser produced plasma UTA emission down to 3 nm for next generation lithography and short wavelength imaging

Cited by 7 publications

References 25 publications

Dielectronic recombination of Rh-like Gd and W

Dielectronic recombination of Rh-like Gd and W

Feasibility study of broadband efficient “water window” source

Investigation of Gd and Tb plasmas for beyond extreme ultraviolet lithography based on multilayer mirror performance

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