Behavior of debris from laser-produced plasma for extreme ultraviolet light source measured by laser imaging technique

Tanaka, Hiroki; Hashimoto, Yuki; Tamaru, K.; Takahashi, Akihiko; Okada, Tatsuo

doi:10.1063/1.2362591

Cited by 25 publications

(15 citation statements)

References 10 publications

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“…The LPP emits debris in the form of energetic ions, atoms, and molten droplets, which are difficult to control. 9,[19][20][21][22] This ablated target material vapor-deposits itself on various components within a direct line-of-sight of the plasma, including the surface of the MLM, which causes degradation in mirror reflectivity. Additional reflectivity losses are a result of ioninduced sputtering damage to the mirror itself.…”

Section: Introductionmentioning

confidence: 99%

Analysis of atomic and ion debris features of laser-produced Sn and Li plasmas

Coons

Harilal

Campos

et al. 2010

Journal of Applied Physics

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Tin and lithium plasmas emit efficiently in the in-band region ͑13.5 nm with 2% bandwidth͒ necessary for extreme ultraviolet ͑EUV͒ lithography. We have made a detailed comparison of the atomic and ionic debris, as well as the emission features of Sn and Li plasmas under identical experimental conditions. Planar slabs of pure Sn and Li were irradiated with 1064 nm, 9 ns neodymium-doped yttrium aluminum garnet laser pulses for producing plasmas. A suite of diagnostics were used to analyze the emission and debris features, including optical emission spectroscopy ͑OES͒, a Faraday cup, an EUV pinhole camera, the absolute measurement of EUV conversion efficiency ͑CE͒, etc. Our results show that Sn plasmas provide a CE nearly twice that of Li. However, the kinetic energies of Sn ions are considerably higher, though with a lower flux. OES studies have showed that the kinetic energies of neutral species are substantially lower compared to that of the charged particle species.

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Section: Introductionmentioning

confidence: 99%

Analysis of atomic and ion debris features of laser-produced Sn and Li plasmas

Coons

Harilal

Campos

et al. 2010

Journal of Applied Physics

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“…Although several methods have been developed for the debris mitigation, including a magnetic field trap of ions [7], foil trap [8], and so on [9], it is difficult to mitigate the neutral particle debris because they can not be controlled by electromagnetic field. In the previous study, it was found that the neutral atoms are originated from the low-intensity part of the laser spot and the deep layer from the target surface [10] and large size debris must be also generated from the same parts. So, the fundamental and general approach for debris mitigation is the use of a minimum amount of Sn that can provide a sufficient EUV power.…”

Section: Introductionmentioning

confidence: 99%

Imaging Diagnostics of Debris from Laser-Produced Tin Plasma with Droplet Target for EUV Light Source

Nakamura¹,

Tomoya

Takahashi

et al. 2008

JLMN

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In this paper we study the influence of the processing wavelength on process efficiency and quality at picosecond microdrilling in steel. Possible optical setups for utilizing the second harmonic will be presented, and the influence of wavelength on the drilling rate will be discussed. The potential of helical drilling with the second harmonic in 1 mm thick CrNi-steel will be investigated with regard to process efficiency and hole quality. An analysis will be given of the role of particle-ignited atmospheric plasma and the relation between isophote contour and hole morphology. Our study reveals that a substantial enhancement of both precision and productivity can be achieved by using frequency-doubled instead of infrared radiation. It is shown that plasma ablation and melt production can be minimized by drilling with the second harmonic.

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“…Figure 1 shows the dependence of CEs on the shapes and thicknesses The number of Sn atoms contained inside the dot diameter (500 µm) and the 10 nm of thickness is 7.3 × 10 13 , and radiant energy of in-band light is 10.5 mJ, which corresponds to 7.1 × 10 14 photons. Therefore each Sn atom emits 9.8 photons/atom of in-band light.…”

Section: Minimum Mass Of Sn Fuel For Sufficient Euv Radiant Energymentioning

confidence: 99%

“…2, minimum-mass Sn fuel for sufficient EUV radiation is discussed in Sec. 3 [10][11][12], reduction of neutral debris emanation is demonstrated [12,13] in Sec. 4, suppression of OOB radiation is demonstrated [14,15] Sec.…”

Section: Introductionmentioning

confidence: 99%

Laser Production of Extreme Ultraviolet Light Source for the Next Generation Lithography Application

Fujioka

Nishimura

Nishihara

et al. 2009

Plasma and Fusion Research

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Extreme ultraviolet lithography (EUVL) is a technology to be used in mass production of the next-generation semiconductor devices. Critical issues in the development of a Sn-based EUV source are in achieving a high conversion efficiency (CE) of incident laser energy into EUV light, reducing debris emanating from light source plasmas, and suppressing out-of-band radiation beside the EUV light. The minimum-mass target, which contains the minimum number of Sn atoms required for sufficient EUV radiation, is a solution to these critical issues. One practical-minimum mass target is a pure Sn microdroplet. Laser-driven expansion of a pure Sn microdroplet is proposed to solve the considerable mismatch between the optimal laser spot diameter (300 µm) and the diameter (20 µm) of microdroplets containing the minimum-mass Sn fuel for generating the required EUV radiant energy (10 mJ/pulse). An expanded microdroplet was irradiated with a CO 2 laser pulse to generate EUV light. A combination of low density and long scale length of the expanded microdroplet leads to a higher EUV energy CE (4%) than that (2.5%) obtained from planar Sn bulk targets irradiated by a single CO 2 laser pulse. This scheme can be used to produce a practical EUV light source system with an EUV CE of 3.9%.

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Behavior of debris from laser-produced plasma for extreme ultraviolet light source measured by laser imaging technique

Cited by 25 publications

References 10 publications

Analysis of atomic and ion debris features of laser-produced Sn and Li plasmas

Analysis of atomic and ion debris features of laser-produced Sn and Li plasmas

Imaging Diagnostics of Debris from Laser-Produced Tin Plasma with Droplet Target for EUV Light Source

Laser Production of Extreme Ultraviolet Light Source for the Next Generation Lithography Application

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