EUV laser produced plasma source development for lithography (Invited Paper)

Hayden, P.; Sheridan, Paul; O'Sullivan, Gerry; Dunne, Padraig; Gaynor, Lynn; Murphy, Nicola; Cummings, A.

doi:10.1117/12.604853

Cited by 4 publications

(3 citation statements)

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“…However, if the laser power density is chosen correctly then a very bright unresolved transition array(s) (UTA(s)) [34][35][36][37][38][39][40][41][42][43][44][45][46] can form in the 13.5 nm EUV regime. These quasi-continua are mainly due to the 4p 6 4d N -4p 5 4d N +1 + 4p 6 4d N −1 4f transition arrays formed predominantly from the ion stages Sn 8+ to Sn 13+ (6 N 1) [7,8,10,38,39].…”

Section: Introductionmentioning

confidence: 99%

A spatio-temporal study of variable composition laser-produced Sn plasmas

Cummings¹,

O'Sullivan²,

Dunne³

et al. 2005

J. Phys. D: Appl. Phys.

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Laser-produced Sn plasmas are at present a major contender in the challenge to find a suitable replacement for the currently used excimer-laser technology, which has wavelengths of 248 and 193 nm, and that is utilized in projection lithography. These wavelengths are to be superseded by soft x-ray sources in the 13.5 nm wavelength regime for utilization in extreme ultraviolet lithographic (EUVL) technologies. To date, considerable international efforts have been channelled into the experimental realization and optimization of various tin based EUV sources. Therefore, in order to compliment these experimental accomplishments we have undertaken a spatio-temporal study of the free electron number density, atomic number density, average charge state and expansion kinetic energy of Sn and SnO2 plasmas. This has been achieved by coupling the collisional radiative equations to the one-dimensional Lagrangian fluid dynamic model MED103 (MEDUSA), thus obtaining the spatial and temporal histories of the aforementioned variables within a laser-produced plasma of spherical geometry, generated using a Gaussian laser pulse at 1064 nm. The evolution of ion stages Sn4+ to Sn13+ within a fluid cell is also presented. In addition, the dependence of the Sn fractional ion populations upon the atomic number density within variable composition plasmas of binary mixtures formed from Sn and oxygen and Sn combined with samarium is investigated. The overwhelming influence of both the atomic and free electron number densities within these plasmas is highlighted.

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Section: Introductionmentioning

confidence: 99%

A spatio-temporal study of variable composition laser-produced Sn plasmas

Cummings¹,

O'Sullivan²,

Dunne³

et al. 2005

J. Phys. D: Appl. Phys.

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“…In the prepulse case, the density profile of the generated plasma is dependent on the delay between the two pulses and on the relative pulse energies as well [16]. At 13.5 nm an intensity increase of 70% has been observed, when the prepulse was delayed by several ns with respect to the main pulse [10].…”

mentioning

confidence: 98%

“…The spectral distribution of the radiation in an unresolved transition array (UTA) is rather wide with the maximum at around 13.5 nm [6,7]. At the beginning of the development of laserplasma EUV sources, the tin target was in the form of a thin foil or sheet of metal [8][9][10]. The theoretical analysis has shown that a target made solely of tin is ineffective because the ionic concentration in the plasma is too high.…”

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confidence: 99%

Laser-produced plasma EUV source based on tin-rich, thin-layer targets

et al. 2010

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In this paper a new approach to a laser-produced plasma EUV source based on a tin target is presented. A thin layer of pure tin and composite layers consisting of Sn with Si, SiO and LiF are investigated. The target composed of several thin layers produces less debris than the other targets and provides a conversion efficiency (CE) in the 13.5-nm ± 1% band at least comparable to the CE for the pure tin slab target. The largest CE was observed for the target composed of a mixture of Sn and LiF, due to the fact that lithium, similarly to tin, is a strong emitter at 13.5 nm.

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13.5 nm extreme ultraviolet emission from tin based laser produced plasma sources

Hayden

Cummings

Murphy

et al. 2006

Journal of Applied Physics

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An examination of the influence of target composition and viewing angle on the extreme ultraviolet spectra of laser produced plasmas formed from tin and tin doped planar targets is reported. Spectra have been recorded in the 9–17nm region from plasmas created by a 700mJ, 15ns full width at half maximum intensity, 1064nm Nd:YAG laser pulse using an absolutely calibrated 0.25m grazing incidence vacuum spectrograph. The influence of absorption by tin ions (SnI–SnX) in the plasma is clearly seen in the shape of the peak feature at 13.5nm, while the density of tin ions in the target is also seen to influence the level of radiation in the 9–17nm region.

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EUV laser produced plasma source development for lithography (Invited Paper)

Cited by 4 publications

References 0 publications

A spatio-temporal study of variable composition laser-produced Sn plasmas

A spatio-temporal study of variable composition laser-produced Sn plasmas

Laser-produced plasma EUV source based on tin-rich, thin-layer targets

13.5 nm extreme ultraviolet emission from tin based laser produced plasma sources

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