Estimation of optimum density and temperature for maximum efficiency of tin ions in Z discharge extreme ultraviolet sources

Masnavi, Majid; Nakajima, Mitsuo; Hotta, Eiki; Horioka, Kazuhiko; Niimi, Gohta; Sasaki, Akira

doi:10.1063/1.2434987

Cited by 30 publications

(12 citation statements)

References 48 publications

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“…measured with Normarski interferometer. The electron density related to the maximum EUV emission is (2 − 3) × 10 18 cm −3 which is within the optimum density for the in-band EUV emission given by simulation result [7] .…”

Section: Laser-assisted Tin Dpp Euv Sourcesupporting

confidence: 80%

Extreme ultraviolet light sources and soft x-ray laser based on discharge produced plasma

et al. 2015

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Due to the demand to realize shorter wavelength light sources, extreme ultraviolet (EUV) sources and soft x-ray laser (SXRL) are under development. The development of EUV sources at the wavelength of 13.5 nm started to realize light sources to be used for next generation lithography. Xenon was used at the beginning of development, however, to attain higher conversion efficiency, tin is now used as fuel. As a coherent light source, capillary discharge SXRL is under development. After the demonstration of Ne-like Ar SXRL by using electron collisional excitation scheme, the effort to shorten the wavelength has been made by adopting recombination scheme such as H-like N. Though the challenge has not yet been successful, the source has potential to be used as a SXR source in the water window wavelength region. Current status of EUV and SXR sources based on discharge produced plasma will be given. EUV source, SXR laser, Capillary discharge, Z-pinch, Discharge produced plasma 1. INTRODUCTION To meet the requirement for the next generation lithography, the research and development of 13.5 nm extreme ultraviolet (EUV) light sources based on discharge produced plasma (DPP) has been energetically pushed forward for the last decade. Although the research started from a xenon (Xe) capillary DPP EUV source, to reduce the interaction between plasma and the capillary inner wall, a Xe gas jet EUV source without a capillary was developed and the formation of EUV emission plasma with a small diameter at discharge current of 10 kA was successfully realized. The obtained EUV conversion efficiency of Xe plasma is less than 1%. In order to increase the conversion efficiency, which leads to the reduction of thermal load on the discharge head, a laser assisted DPP tin (Sn) EUV source has been also studied. It was demonstrated

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Section: Laser-assisted Tin Dpp Euv Sourcesupporting

confidence: 80%

Extreme ultraviolet light sources and soft x-ray laser based on discharge produced plasma

et al. 2015

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“…Because the plasma expansion processes after the maximum implosion in a LDP EUV source and after laser ablation in a LPP EUV source can both be considered as dominated by adiabatic expansion into the vacuum, and because the EUV-emitting plasmas in both sources have similar electron temperatures, 8,9 we can safely assume that particles in these two cases share similar motion-patterns during expansion. In our previous study on the characteristics of LPP, the expansion behaviors of electrons and neutrals were investigated using Stark broadening and laser induced fluorescence, respectively.…”

Section: Discussionmentioning

confidence: 99%

“…Tin fueled laser-assisted discharge plasma (LDP) proves to be a powerful light source for the generation of sufficient in-band 13.5 nm EUV emission. [4][5][6][7] LDP is also of great commercial interest because of its preferable conversion efficiency 8,9 and simplicity compared to other methods. In the LDP source, 13.5 nm EUV emission is generated from the hot and dense Z-pinch implosion plasma created by a laser triggered vacuum arc.…”

Section: Introductionmentioning

confidence: 99%

Estimation of electron temperature and density of the decay plasma in a laser-assisted discharge plasma extreme ultraviolet source by using a modified Stark broadening method

Zhu

Muto

Yamada

et al. 2011

Journal of Applied Physics

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In order to investigate the plasma expansion behaviors and the electrical recovery process after the maximum implosion in our tin fueled laser-assisted discharge plasma (LDP) 13.5 nm EUV source, we developed and evaluated a cost-efficient spectroscopic method to determine the electron temperature T e and density n e simultaneously, by using Stark broadenings of two Sn II isolated lines (5s 2 4f 2 F 5/2-5s 2 5d 2 D 3/2 558.9 nm and 5s 2 6d 2 D 5/2-5s 2 6p 2 P 3/2 556.2 nm) spontaneously emitted from the plasma. The spatial-resolved evolutions of T e and n e of the expansion plasma over 50 to 900 ns after the maximum implosion were obtained using this modified Stark broadening method. According to the different n e decay characteristics along the Z-pinch axis, the expansion velocity of the electrons was estimated as $1.2 Â 10 4 ms À 1 from the plasma shell between the electrodes towards the cathode and the anode. The decay time constant of n e was measured as 183 6 24 ns. Based on the theories of plasma adiabatic expansion and electron-impact ionization, the minimum time-span that electrical recovery between the electrodes needs in order to guarantee the next succeeding regular EUV-emitting discharge was estimated to be 70.5 ls. Therefore, the maximum repetition rate of our LDP EUV source is $14 kHz, which enables the output to reach 125 W/(2psr). V

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“…The ideal plasma source for emission into a 2% band centered at 13.5nm has an electron temperature between 35 and 40 electron volts (eV), and an electron density of 10 18~1 0 19 cm -3 [17].…”

Section: Introductionmentioning

confidence: 99%

Observations and analysis of extreme ultraviolet emission by capillary discharge with Xe as target

Zhao

Zhi-liang

et al. 2010

2010 Academic Symposium on Optoelectronics and Microelectronics Technology and 10th Chinese-Russian Symposium on Laser Physics

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The first capillary discharge produced plasma extreme ultraviolet source has been started in China. Fundamental characteristics of DPP including current, Xe gas pressure, extreme ultraviolet energy and spectrum in extreme ultraviolet region have been studied. A high voltage power source is employed, which voltage can be changed from 20kV to 30kV, and the current is from 25kA to 45kA with a FWHM of 120ns. The high voltage is loaded between the capillary which is 3mm in diameter and 12mm in length by injected Xe gas to achieve extreme ultraviolet radiation mostly in the region 10nm~18nm developed in framework of an extreme ultraviolet lithograph program. It is founded that the in-band (13.5nm, 2% bandwidth) energy is increasing with decreasing Xe gas pressure and/or increasing the current in the region 5~10Pa and 25kA~45kA.And 0.56J/2π sr/pulse energy (13.5nm, 2% bandwidth) can be got when the input energy is 47.7J, and the conversion efficiency is 0.56%.

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Estimation of optimum density and temperature for maximum efficiency of tin ions in Z discharge extreme ultraviolet sources

Cited by 30 publications

References 48 publications

Extreme ultraviolet light sources and soft x-ray laser based on discharge produced plasma

Extreme ultraviolet light sources and soft x-ray laser based on discharge produced plasma

Estimation of electron temperature and density of the decay plasma in a laser-assisted discharge plasma extreme ultraviolet source by using a modified Stark broadening method

Observations and analysis of extreme ultraviolet emission by capillary discharge with Xe as target

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