High-conversion-efficiency tin material laser-plasma source for EUVL

Koay, Chiew-Seng; Keyser, Christian; Takenoshita, Kazutoshi; Fujiwara, Etsuo; Al-Rabban, Moza M.; Richardson, Martin; Turcu, I. C. Edmond; Rieger, Harry; Stone, A. Douglas; Morris, James H.

doi:10.1117/12.504572

Cited by 17 publications

(9 citation statements)

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“…However, the highest CE obtained so far was achieved with a liquid stream containing tin (5% as mentioned above). The tin content by mass was up to a few tens of percent [39,40]. Similar experiments were conducted in the Institute of Optoelectronics between 2005 and 2006.…”

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confidence: 54%

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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supporting

confidence: 54%

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

et al. 2010

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“…However, this stagnation of LPP power was what we anticipated at that time because we did not hear new proposals of target delivery. Some people tried conventional melted Sn jet [8] or a tin-doped solution [9], but with these ideas, we can not expect high efficiency as is made clear in discussions in the next section.…”

Section: Introductionmentioning

confidence: 95%

EUV generation using a droplet of a suspension including tin as a target of a high-efficiency LPP source for high volume production

et al. 2006

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Technologies for materializing our cotton-cake like tin target scheme are being developed. With the scheme, we expect to achieve 4% conversion efficiency into 2π sr supported by our experimental data. In order to implement EUVL, EUV power exceeding 100 W is considered to be required to be sent to an illumination box. Large collection solid angle and high conversion efficiency are the mandatory requirements for a source for EUVL. A route to the goal is not yet clear. With our scheme, we can expect EUV exceeding 100 W at the entrance of an illuminator is obtained with a 15 kW YAG laser. Difficulties we encountered when we tried plasma production by shooting droplets of a SnO 2 suspension were preparation of a long life SnO 2 suspension and stable droplet generation with the suspension. In these few years our technologies are highly improved, and we are now able to supply the suspension for several hours without stop, and concentration of a suspension is now increased to as high as 40 wt %. EUV intensity dependence on concentration was studied by shooting a jet of a suspension. We found the EUV intensity saturated at around several at %, which corresponds to several tens wt%, and the EUV intensity comparable to that from a Sn plate was observed. By introducing active synchronization of laser pulses with droplets, we can now shoot droplets running at 10 kHz with a 10 Hz YAG laser with no miss shot. We are now ready to challenge formation of cotton-cake like tin target to demonstrate a very high CE.

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“…Spatial fluctuation also easily happens by a small mechanical defect of the nozzle. An alternative is a micro droplet technology with more efficient material like Sn within liquids [10]. A typical concept is shown in Fig.7 with relating parameters for stability analysis.…”

Section: Fig6 Liquid Jet With Geometrical Parameters Fig7 Droplet Wmentioning

confidence: 99%

Fluctuation of laser-induced x-rays from electron beam and plasma

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2003

SPIE Proceedings

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There has been a significant progress in the X-ray generation technologies for various laboratory and production applications by laser-Compton scheme and laser produced plasma. Femtosecond X-ray generation was performed by Compton scattering through interaction between a 3-ps electron beam and 100-fs laser photons in a 90 degree scattering configuration. The X-ray energy and pulse duration were estimated as 2.3keV and 280fs from the observed electron and laser beam parameters. The fluctuation of the X-ray output was measured as 25% (1σ) during 30-min operation, and analyzed as a function of fluctuations of parameters like timing between the electron and laser beam, electron beam charge, laser beam energy, pulse widths, and spatial stability. Further reduction of the fluctuation is possible by improvement of component stability. All optical synchronization was proposed and component technologies are under development. The novel scheme employs optical control of the RF phase of the linear accelerator and femtosecond lasers by optical locking of lasing between different laser oscillators. Two mode-locked Ti:sapphire lasers of different wavelengths were precisely synchronized by a simple feedback system employing sum frequency generation. The measured timing jitter between two lasers was 28fs. The optical locking technology enables to achieve 3% (1ǻ) X-ray fluctuation with improvements of other parameters.Clean EUV light source is strongly demanded for next generation lithography, with 13.5nm, 2% bw, 100W at clean focus and high pulse stability of less than 1%(3σ). The most promising approach is to employ a liquid Xe jet of 10-100 Ǵ m diameter as the plasma source with a high repetition rate solid state laser. The laser pulse energy usually fluctuates more than a few % and the liquid jet fluctuates of the position up to 10% of the diameter. Higher repetition rate plasma generation causes acoustic instability inside the liquid jet and limits the stable operation. All these obstacles prevent to achieve the desired EUV stability. Discussion will be given on these issues and the analysis of the spatial fluctuation is shown on the available pulse to pulse stability. The architecture by multiple-pulse averaging is evaluated to achieve a clean EUV light source with required stability.

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High-conversion-efficiency tin material laser-plasma source for EUVL

Cited by 17 publications

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

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

EUV generation using a droplet of a suspension including tin as a target of a high-efficiency LPP source for high volume production

Fluctuation of laser-induced x-rays from electron beam and plasma

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