Comparative study on EUV and debris emission from CO<sub>2</sub>and Nd: YAG laser-produced tin plasmas

Takahashi, Akihiko; Nakamura, Daisuke; Tamaru, K.; Akiyama, Tsuyoshi; Okada, Tatsuo

doi:10.1088/1742-6596/112/4/042059

Cited by 6 publications

(3 citation statements)

References 4 publications

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“…1 Sn is considered as the source for EUV plasma due to its high conversion efficiency ͑CE͒ from laser to 13.5 nm ͑3% bandwidth͒ EUV emission. In this regard, most of the previous studies of Sn LPP have focused to increase the CE of the EUV light source and decrease the debris using different laser wavelength, [6][7][8][9] different pulse duration, and samples with different thickness and different percentage of Sn, 10 etc. The debris limit the lifetime of the expensive and delicate Mo/Si multilayer collector.…”

Section: Introductionmentioning

confidence: 99%

Spectroscopic analysis of temperature and density of Sn plasma produced by a CO2 laser

Shaikh

Tao

Burdt

et al. 2010

Journal of Applied Physics

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Articles you may be interested inA method to measure the electron temperature and density of a laser-produced plasma by Raman scattering Electronic temperature and density of the plasma produced by nanosecond ultraviolet laser ablation of LiF Density and temperature sensitive line ratios in plasmas generated by laser ablation Electron density and temperature measurements in a laser produced carbon plasmaThe temporal and spatial evolution of electron temperature and electron density from Sn plasma produced by a CO 2 laser has been investigated in vacuum using spectroscopic methods. The plasma parameters were inferred by the Boltzmann plot method from experimentally observed line profiles of singly ionized Sn and Stark broadened profiles. At a laser intensity of 10 10 W / cm 2 , electron temperature and density were measured to be within 1.13 eV to 0.53 eV and 5.3ϫ 10 16 cm −3 to 1.4ϫ 10 16 cm −3 , respectively, for delay times between 200 ns and 1100 ns, and at distances up to 5 mm along the target normal. The results show the electron temperature and density from Sn plasma produced by a CO 2 laser with wavelength of 10.6 m to be lower than previously reported results using a 1064 nm laser in a similar parameter regime. The lower temperature in the region far away from the target surface confirms the smaller interaction region for CO 2 laser as compared with that of neodymium-doped yttrium aluminum garnet laser.

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Section: Introductionmentioning

confidence: 99%

Spectroscopic analysis of temperature and density of Sn plasma produced by a CO2 laser

Shaikh

Tao

Burdt

et al. 2010

Journal of Applied Physics

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“…For example, while debris production is more pronounced for Nd:YAG lasers, CO 2 laser beams produce more energetic ions at the optimum conditions for laser energy intensities needed for maximum EUV production. 1,2 Additionally the impact of plasma fast ions and the deposition of atomic debris and the deposition of EUV and out of band radiation can further cause surface erosion and damage at the required higher 1932-5150/2011/$25.00 C 2011 SPIE fluences of the 13.5 nm radiation needed for high volume manufacturing. 3 The lower mass ablation rate by the CO 2 laser beams with the longer wavelength and comparatively low value of the critical density for absorption of these photons allow source operation using longer pulses (100 ns and more) without significant reduction in the efficiency of EUV output.…”

Section: Introductionmentioning

confidence: 99%

Combined effects of prepulsing and target geometry on efficient extreme ultraviolet production from laser produced plasma experiments and modeling

Hassanein¹

2011

J. Micro/Nanolith. MEMS MOEMS

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Laser produced plasmas (LPPs) are currently a promising source of an efficient extreme ultraviolet (EUV) photon source production for advanced lithography. Optimum laser pulse parameters with adjusted wavelength, energy, and duration for a simple planar or spherical tin target can provide 2% to 3% conversion efficiency (CE) in laboratory experiments. Additional effects such as targets with complex geometry and tin-doped targets using prepulsing of laser beams can significantly increase CE. Recent studies showed that such improvements in an LPP system are due to reduction in laser energy losses by decreasing photons transmission (higher harmonic of Nd:yttrium-aluminum-garnet laser) or photons reflection (for CO 2 laser). Optimization of target heating using prepulses or ablating low-density and nanoporous tin oxide can further improve LLP sources by creating more efficient plasma plumes and, as a result, increase CE, the most important parameter for EUV sources. We investigated the combined effects of prepulsing with various parameters and different target geometries on EUV conversion efficiency and on energetic ions production. The much higher reflectivity of CO 2 laser from a tin target leads to two possible ways for system improvement using prepulses with shorter laser wavelengths or using more complex targets geometries with special grooves as developed previously by the authors. C 2011 Society of Photo-Optical Instrumentation Engineers (SPIE).

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“…Damage of multilayer Mo/Si mirrors by the debris products of laser beam interaction with target materials can significantly reduce their lifetime and as result the efficiency and the economy of the entire EUVL system. For example, while debris production is more pronounced for Nd:YAG lasers, CO 2 laser beams produce more energetic ions at the optimum conditions for laser energy intensities needed for maximum EUV production [1], [2]. Additionally the impact of plasma fast ions and the deposition of atomic debris and the deposition of EUV and out of band radiation can further cause surface erosion and damage at the required higher fluences of the 13.5 nm radiation needed for high volume manufacturing [3].…”

Section: Introductionmentioning

confidence: 99%

Combined effects of pre-pulsing and target geometry on efficient EUV production from laser produced plasma experiments and modeling

Hassanein

Sizyuk

et al. 2011

SPIE Proceedings

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Laser produced plasmas (LPP) is currently a promising source of an efficient extreme ultraviolet (EUV) photon source production for advanced lithography. Optimum laser pulse parameters with adjusted wavelength, energy, and duration for simple planar or spherical tin target can provide 2-3% conversion efficiency (CE) in laboratory experiments. These values are also in good agreement with modeling results. Additional effects such as targets with complex geometry and tin-doped targets using pre-pulsing of laser beams can significantly increase CE. Recent studies showed that such improvements in LPP system are due to reduction in laser energy losses by decreasing photons transmission (higher harmonic of Nd:YAG laser) or photons reflection (for CO 2 laser). Optimization of target heating using pre-pulses or ablating low-density and nanoporous tin oxide can further improve LLP sources by creating more efficient plasma plumes and as a result increasing CE, the most important parameter for EUV sources. The second important challenge in developing LPP devices is to decrease fast ions and target debris to protect the optical collection system and increase its lifetime.We investigated the combined effects of pre-pulsing with various parameters and different target geometries on EUV conversion efficiency and on energetic ions production. The much higher reflectivity of CO 2 laser from a tin target leads to two possible ways for system improvement using pre-pulses with shorter laser wavelengths or using more complex targets geometries with special grooves as developed previously by the authors.

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Comparative study on EUV and debris emission from CO₂and Nd: YAG laser-produced tin plasmas

Cited by 6 publications

References 4 publications

Spectroscopic analysis of temperature and density of Sn plasma produced by a CO2 laser

Spectroscopic analysis of temperature and density of Sn plasma produced by a CO2 laser

Combined effects of prepulsing and target geometry on efficient extreme ultraviolet production from laser produced plasma experiments and modeling

Combined effects of pre-pulsing and target geometry on efficient EUV production from laser produced plasma experiments and modeling

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Comparative study on EUV and debris emission from CO2and Nd: YAG laser-produced tin plasmas

Cited by 6 publications

References 4 publications

Spectroscopic analysis of temperature and density of Sn plasma produced by a CO2 laser

Spectroscopic analysis of temperature and density of Sn plasma produced by a CO2 laser

Combined effects of prepulsing and target geometry on efficient extreme ultraviolet production from laser produced plasma experiments and modeling

Combined effects of pre-pulsing and target geometry on efficient EUV production from laser produced plasma experiments and modeling

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Comparative study on EUV and debris emission from CO₂and Nd: YAG laser-produced tin plasmas