Extreme-ultraviolet spectral purity and magnetic ion debris mitigation by use of low-density tin targets

Harilal, S. S.; Tillack, M. S.; Tao, Y.; O'Shay, B; Paguio, R. R.; Nikroo, A.

doi:10.1364/ol.31.001549

Cited by 48 publications

(29 citation statements)

References 19 publications

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“…This also coincides with observations of lowdensity Sn-doped foam, SnO 2 , and targets with low Sn concentration. [24][25][26][27] In the case of the dual pulse, laser energy is deposited in the preformed plume with a smooth density profile. The ablation pressure is reduced with a smooth initial density profile, because the laser is absorbed in the lower densities farther from the ablation surface.…”

Section: -6mentioning

confidence: 99%

Investigation of the interaction of a laser pulse with a preformed Gaussian Sn plume for an extreme ultraviolet lithography source

Tao

Tillack

Harilal

et al. 2007

Journal of Applied Physics

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The interaction of a laser pulse with a Sn preplasma formed by a low energy prepulse was investigated for an extreme ultraviolet ͑EUV͒ lithography light source. A much lower ion kinetic energy and nearly the same conversion efficiency from laser to in-band ͑2% bandwidth͒ 13.5 nm EUV light were simultaneously observed as compared with those from the direct interaction with a solid surface. The reason comes from the interaction of the laser pulse with a smooth preplume induced by the prepulse. The density profile of the preplume was measured with time-resolved shadowgraphy and could be fitted with a Gaussian function. The energy of the ions located at the flux peak E p scales with the length of the preplume l s as E p ϰ 1/l s . Laser absorption in the low-density preplume and ion acceleration during plasma expansion are discussed. This result provides a general way to control particle energy from a laser plasma interaction.

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Section: -6mentioning

confidence: 99%

Investigation of the interaction of a laser pulse with a preformed Gaussian Sn plume for an extreme ultraviolet lithography source

Tao

Tillack

Harilal

et al. 2007

Journal of Applied Physics

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“…These include target geometry, laser parameters, laser irradiation scheme, and debris mitigation techniques. 5,14 For generating Sn plasmas, several target geometries have been explored, including thin film, 15 planar slab, 16 grooved planar slab, 11 Sn-doped foam, 17 and microdroplet. 12,18,19 Grooved planar Sn targets have been shown to achieve CE of 5% because the grooves cause hydrodynamic confinement of the plasma, generating an area of efficient EUV production.…”

Section: Introductionmentioning

confidence: 99%

Enhancements of extreme ultraviolet emission using prepulsed Sn laser-produced plasmas for advanced lithography applications

Freeman

Harilal

Hassanein

2011

Journal of Applied Physics

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Laser-produced plasmas (LPP) from Sn targets are seriously considered to be the light source for extreme ultraviolet (EUV) next generation lithography, and optimization of such a source will lead to improved efficiency and reduced cost of ownership of the entire lithography system. We investigated the role of reheating a prepulsed plasma and its effect on EUV conversion efficiency (CE). A 6 ns, 1.06 lm Nd:yttrium aluminum garnet laser was used to generate the initial plasma that was then reheated by a 40 ns, 10.6 lm CO 2 laser to generate enhanced EUV emission from a planar Sn target. The effects of prepulsed laser intensity and delay timings between the prepulsed and the pumping pulse were investigated to find the optimal pre-plasma conditions before the pumping pulse. The initial optimization of these parameters resulted in 25% increase in CE from the tin LPP. The cause of increased EUV emission was identified from EUV emission spectra and ion signal data.

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“…This is different from the result obtained with a Nd:YAG laser. In that case, a target with a low concentration of Sn showed a comparable or even slightly higher in-band CE as compared with that of a solid tin target [9]. A typical soft X-ray spectrum from the foam target is shown in Fig.…”

Section: Resultsmentioning

confidence: 83%

Interaction of a $\hbox{CO}_{2}$ Laser Pulse With Tin-Based Plasma for an Extreme Ultraviolet Lithography Source

Tao

Tillack

Yuspeh

et al. 2010

IEEE Trans. Plasma Sci.

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The interaction of a CO 2 laser pulse with Sn-based plasma for a 13.5-nm extreme ultraviolet (EUV) lithography source was investigated. It was noted that a CO 2 laser with wavelength of 10.6 μm is more sensitive to surface impurities as compared with a Nd:YAG laser with wavelength of 1.06 μm. This reveals that a CO 2 laser is more likely absorbed in a thinner layer near the target surface. Compared with a Nd:YAG laser, a CO 2 laser shows higher in-band (2% bandwidth) conversion efficiency (CE) with a solid Sn target due to less reabsorption of the EUV emission induced by the plasma. However, with foam targets containing low concentrations of Sn, the in-band CE is lower than that with solid Sn. The CE can be enhanced with plasma confinement. These results suggest that a driving laser with wavelength between 1.06 and 10.6 μm may be an even better choice to generate higher CE from laser to 13.5-nm EUV emission.Index Terms-CO 2 laser, extreme ultraviolet (EUV) source, plasma.

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Extreme-ultraviolet spectral purity and magnetic ion debris mitigation by use of low-density tin targets

Cited by 48 publications

References 19 publications

Investigation of the interaction of a laser pulse with a preformed Gaussian Sn plume for an extreme ultraviolet lithography source

Investigation of the interaction of a laser pulse with a preformed Gaussian Sn plume for an extreme ultraviolet lithography source

Enhancements of extreme ultraviolet emission using prepulsed Sn laser-produced plasmas for advanced lithography applications

Interaction of a $\hbox{CO}_{2}$ Laser Pulse With Tin-Based Plasma for an Extreme Ultraviolet Lithography Source

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