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Journal Articles

Modeling of initial interaction between the laser pulse and Sn droplet target and pre-plasma formation for the LPP EUV source

Sasaki, Akira; Nishihara, Katsunobu*; Sunahara, Atsushi*; Nishikawa, Takeshi*

Proceedings of SPIE, Vol.9776, p.97762C_1 - 97762C_6, 2016/03

 Times Cited Count:1 Percentile:55.81

For the improvement of efficiency and output of the laser pumped plasma (LPP) extreme ultra-violet (EUV) light source, we present a hydrodynamics model of laser irradiated Sn targets. The model takes liquid/solid to gas transition and mixed phase condition of the flow into account for the calculation of the distribution of the particles produced by the pre-pulse laser irradiation and optimization of the EUV source. Firstly, we investigate the mechanisms of the fragmentation of the target and particle emission, including the effect of the equation of state of Sn, and secondly, an applicable model is proposed based on the analysis.

Journal Articles

Modeling of atomic processes of multiple charged ions in plasmas and its application to the study of EUV light sources

Sasaki, Akira; Nishihara, Katsunobu*; Sunahara, Atsushi*; Furukawa, Hiroyuki*; Nishikawa, Takeshi*; Koike, Fumihiro*

Plasma and Fusion Research (Internet), 6(Sp.1), p.2401145_1 - 2401145_4, 2011/12

Atomic processes and radiation from multiple charged ions in plasmas are of the interest in the investigation of plasma wall interaction and transport of impurity ions in the fusion devices. The emission from multiple charged ions is also investigated for the development of extreme ultra violet light (EUVL) sources at $$lambda=13.5 nm$$. Efficient emission through the 4d-4f + 4p-4d transition array is obtained from tin ions. An optimization of pumping conditions of laser produced plasma sources is carried out theoretically and experimentally. We also investigate an extension of the plasma light sources to short wavelength to $$lambda=6.5 nm$$ using Gd and Tb plasmas. We discuss requirements to the atomic structure, rate coefficient and collisional radiative codes to determine ion abundance and level population as a function of plasma temperature and density, to calculate the radiation intensity as well as emission spectrum.

Journal Articles

Theoretical investigation of the spectrum and conversion efficiency of short wavelength extreme-ultraviolet light sources based on terbium plasmas

Sasaki, Akira; Nishihara, Katsunobu*; Sunahara, Atsushi*; Furukawa, Hiroyuki*; Nishikawa, Takeshi*; Koike, Fumihiro*

Applied Physics Letters, 97(23), p.231501_1 - 231501_3, 2010/12

 Times Cited Count:14 Percentile:52.5(Physics, Applied)

Emission spectrum and conversion efficiency of laser produced terbium plasmas are investigated theoretically on the basis of computational atomic data. It is shown that calculation reproduces the main peak of the experimental spectrum at $$lambda=6.5$$nm, which originates from 4$$d$$-4$$f$$ transitions of near palladium like ions (Tb$$^{19+}$$). Simple model of the isothermal expansion of plasma suggests that efficient emission can be obtained by pumping a plasma with a laser pulse with an intensity approximately one order of magnitude grater than in the case of tin sources at $$lambda=13.5$$nm.

Journal Articles

Modeling of radiative properties of Sn plasmas for extreme-ultraviolet source

Sasaki, Akira; Sunahara, Atsushi*; Furukawa, Hiroyuki*; Nishihara, Katsunobu*; Fujioka, Shinsuke*; Nishikawa, Takeshi*; Koike, Fumihiro*; Ohashi, Hayato*; Tanuma, Hajime*

Journal of Applied Physics, 107(11), p.113303_1 - 113303_11, 2010/06

 Times Cited Count:33 Percentile:77.65(Physics, Applied)

Atomic processes in Sn plasmas are investigated for application to extreme-ultraviolet (EUV) light sources used in microlithography. An atomic model of Sn is developed on the basis of calculated atomic data using the Hebrew University Lawrence Livermore Atomic Code (HULLAC). Resonance and satellite lines from singly and multiply excited states of Sn ions are identified. The wavelengths of the 4$$d$$-4$$f$$ + 4$$p$$-4$$d$$ transitions of Sn$$^{5+}$$ to Sn$$^{13+}$$ are investigated. Results of calculation are compared with those of the charge exchange spectroscopy, measurement of the emission spectrum of the laser produced plasma EUV source, and the opacity measurement of a radiatively heated Sn sample. A reasonable agreement is observed between calculated and experimental EUV emission spectra. The spectral emissivity and opacity of Sn plasmas are calculated using a full collisional radiative (CR) model as a function of electron temperature and ion density.

Journal Articles

Atomic modeling of the plasma EUV sources

Sasaki, Akira; Sunahara, Atsushi*; Furukawa, Hiroyuki*; Nishihara, Katsunobu*; Nishikawa, Takeshi*; Koike, Fumihiro*; Tanuma, Hajime*

High Energy Density Physics, 5(3), p.147 - 151, 2009/09

 Times Cited Count:9 Percentile:35.94(Physics, Fluids & Plasmas)

We study the radiative properties of the EUV source to address conditions to achieve an output power and efficiency required for its application to the next generation microlithography. An atomic model is developed based on the atomic data calculated by Hullac code, which is validated through detailed comparisons with experimental emission and a absorption spectra. The atomic model is improved with respect to the wavelength of the strong emission lines, and the number of satellite channels taken into account. As a result, the radiation hydrodynamics model is shown to successfully reproduce the experiments. We show Sn plasma is more efficient than Xe plasma because of the atomic number dependence of the emission wavelength, and the use of CO$$_{2}$$ lasers as a pumping source has an advantage to reduce satellite contribution and to have narrower emission spectrum to obtain higher conversion efficiency.

Journal Articles

The Atomic model of the Sn plasmas for the EUV sources

Sasaki, Akira; Sunahara, Atsushi*; Nishihara, Katsunobu*; Nishikawa, Takeshi*; Koike, Fumihiro*; Tanuma, Hajime*

Journal of Physics; Conference Series, 163, p.012107_1 - 012107_4, 2009/06

 Times Cited Count:5 Percentile:85.6

no abstracts in English

Journal Articles

Atomic processes in the LPP and LA-DPP EUV sources

Sasaki, Akira; Nishihara, Katsunobu*; Sunahara, Atsushi*; Furukawa, Hiroyuki*; Nishikawa, Takeshi*; Koike, Fumihiro*

Alternative Lithographic Technologies (Proceedings of SPIE Vol.7271), p.727130_1 - 727130_8, 2009/03

We investigate characteristic feature of the atomic radiation from tin plasmas, which allow one to obtain high power EUV emission efficiently. We develop a collisional radiative model of tin ions to calculate steady-state and time dependent ion abundance, level population, and coefficients of radiative transfer of the plasma. The model, which is based atomic data calculated using the Hullac code is refined both theoretically and experimentally. Calculation of the spectral emissivity and opacity are carried out over a wide range of plasma density and temperature, and pumping conditions to obtain high conversion efficiency are discussed.

Journal Articles

Development of the volume reduction treatment of solid waste system by ultra-high frequency induction furnace

Sakakibara, Tetsuro; Aoyama, Yoshio; Yamaguchi, Hiromi; Sasaki, Naoto*; Nishikawa, Takeshi*; Murata, Minoru*; Park, J.*; Taniguchi, Shoji*; Fujita, Michiru*; Fukuda, Tomoyuki*; et al.

Proceedings of International Waste Management Symposium 2009 (WM '09) (CD-ROM), 15 Pages, 2009/03

The volume reduction treatment of solid waste system by ultra-high frequency induction furnace (UHFIF) was developed from FY2005 to FY2007. Basic data for melting performance were collected by non-radioactive experiments using the bench scale UHFIF with a crucible capacity of 10 liters. Based on the obtained data, engineering specifications were evaluated for a demonstration scale UHFIF with a crucible capacity of 30 liters. A new demonstration scale UHFIF was constructed and melting experiments of surrogate wastes were carried out by this furnace. It was confirmed that the demonstration scale UHFIF can melt ferrous metal, ceramics and aluminum all together and stabilize aluminum by oxidation to alumina. Density, chemical composition, and surface condition of the solidified substances were analyzed, and homogeneity of the solidified substances was confirmed. Melting behavior in the demonstration scale UHFIF was analyzed by computer simulation and simulation results agreed well with the experimental ones. From the design study for a full scale UHFIF with a crucible capacity of 100 liters, basic specifications were evaluated for the full scale UHFIF. Based on the obtained specification, melting behavior in the full scale UHFIF was analyzed by computer simulation.

Journal Articles

Modeling of the atomic processes and photo emission of the plasmas for the EUV source

Sasaki, Akira; Sunahara, Atsushi*; Nishihara, Katsunobu*; Nishikawa, Takeshi*; Koike, Fumihiro*; Tanuma, Hajime*

Reza Kenkyu, 36(Suppl.), p.1132 - 1135, 2008/11

no abstracts in English

Journal Articles

The H-Invitational Database (H-InvDB); A Comprehensive annotation resource for human genes and transcripts

Yamasaki, Chisato*; Murakami, Katsuhiko*; Fujii, Yasuyuki*; Sato, Yoshiharu*; Harada, Erimi*; Takeda, Junichi*; Taniya, Takayuki*; Sakate, Ryuichi*; Kikugawa, Shingo*; Shimada, Makoto*; et al.

Nucleic Acids Research, 36(Database), p.D793 - D799, 2008/01

 Times Cited Count:51 Percentile:73.43(Biochemistry & Molecular Biology)

Here we report the new features and improvements in our latest release of the H-Invitational Database, a comprehensive annotation resource for human genes and transcripts. H-InvDB, originally developed as an integrated database of the human transcriptome based on extensive annotation of large sets of fulllength cDNA (FLcDNA) clones, now provides annotation for 120 558 human mRNAs extracted from the International Nucleotide Sequence Databases (INSD), in addition to 54 978 human FLcDNAs, in the latest release H-InvDB. We mapped those human transcripts onto the human genome sequences (NCBI build 36.1) and determined 34 699 human gene clusters, which could define 34 057 protein-coding and 642 non-protein-coding loci; 858 transcribed loci overlapped with predicted pseudogenes.

Journal Articles

Detailed atomic modeling of Sn plasmas for the EUV source

Sasaki, Akira; Sunahara, Atsushi*; Nishihara, Katsunobu*; Nishikawa, Takeshi*; Koike, Fumihiro*; Tanuma, Hajime*

Journal of Physics; Conference Series, 112, p.042062_1 - 042062_4, 2008/00

 Times Cited Count:4 Percentile:85.41

no abstracts in English

Journal Articles

Plasma physics and radiation hydrodynamics in developing an extreme ultraviolet light source for lithography

Nishihara, Katsunobu*; Sunahara, Atsushi*; Sasaki, Akira; Nunami, Masanori*; Tanuma, Hajime*; Fujioka, Shinsuke*; Shimada, Yoshinori*; Fujima, Kazumi*; Furukawa, Hiroyuki*; Kato, Takako*; et al.

Physics of Plasmas, 15(5), p.056708_1 - 056708_11, 2008/00

 Times Cited Count:109 Percentile:97.47(Physics, Fluids & Plasmas)

Journal Articles

Radiation hydrodynamic simulation of extreme ultra-violet emission from laser-produced tin plasmas

Sunahara, Atsushi*; Sasaki, Akira; Tanuma, Hajime*; Nishihara, Katsunobu*; Nishikawa, Takeshi*; Koike, Fumihiro*; Fujioka, Shinsuke*; Aota, Tatsuya*; Yamaura, Michiteru*; Shimada, Yoshinori*; et al.

Purazuma, Kaku Yugo Gakkai-Shi, 83(11), p.920 - 926, 2007/11

We study the EUV emission from laser produced Sn plasmas using the 1D and 2D radiation hydrodynamics simulation, for the development of EUV source for the next generation semiconductor lithography. The opacity and emissivity of the plasma used in the simulation are calculated by a detailed atomic model, with the accurate wavelength of emission lines obtained from the detailed spectroscopic measurements. Calculation is shown to reproduce the experimental spectrum and conversion efficiency reasonably, including the effect of photo pumping which modifies the EUV emission spectrum in the case with a long scale length of the plasmas.

Journal Articles

Atomic modeling of the plasma EUV sources

Sasaki, Akira; Sunahara, Atsushi*; Nishihara, Katsunobu*; Nishikawa, Takeshi*; Fujima, Kazumi*; Kagawa, Takashi*; Koike, Fumihiro*; Tanuma, Hajime*

High Energy Density Physics, 3(1-2), p.250 - 255, 2007/05

 Times Cited Count:15 Percentile:49.43(Physics, Fluids & Plasmas)

no abstracts in English

Journal Articles

Analysis of the emission spectrum of Xe and Sn

Sasaki, Akira; Nishihara, Katsunobu*; Sunahara, Atsushi*; Nishikawa, Takeshi*; Koike, Fumihiro*; Kagawa, Takashi*; Tanuma, Hajime*

Proceedings of SPIE's International Symposium on Microlithography, Vol.6151, p.61513W_1 - 61513W_8, 2006/03

The atomic processes in the Xe and Sn plasmas are investigated. The wavelength of atomic transitions is shown to have a critical effect in reproducing experiments. The wavelengths of resonance lines in our model are improved through detailed comparison with charge specific spectroscopic measurement. Distribution of satellite lines in the presence of the effect of the configuration interaction (CI) is investigated. The spectral profile of Xe and Sn emission, with determines fraction of usable EUV power, is discussed with respect to its dependence on the plasma temperature, density as well as the optical depth.

Journal Articles

Opacity effect on extreme ultraviolet radiation from laser-produced tin plasmas

Fujioka, Shinsuke*; Nishimura, Hiroaki*; Nishihara, Katsunobu*; Sasaki, Akira; Sunahara, Atsushi*; Okuno, Tomoharu*; Ueda, Nobuyoshi*; Ando, Tsuyoshi*; Tao, Y.*; Shimada, Yoshinori*; et al.

Physical Review Letters, 95(23), p.235004_1 - 235004_4, 2005/12

 Times Cited Count:139 Percentile:95.49(Physics, Multidisciplinary)

no abstracts in English

Journal Articles

Characterization of extreme ultraviolet emission from laser-produced spherical tin plasma generated with multiple laser beams

Shimada, Yoshinori*; Nishimura, Hiroaki*; Nakai, Mitsuo*; Hashimoto, Kazuhisa*; Yamaura, Michiteru*; Tao, Y.*; Shigemori, Keisuke*; Okuno, Tomoharu*; Nishihara, Katsunobu*; Kawamura, Toru*; et al.

Applied Physics Letters, 86(5), p.051501_1 - 051501_3, 2005/01

 Times Cited Count:110 Percentile:94.58(Physics, Applied)

no abstracts in English

Journal Articles

Effect of the satellite lines and opacity on the extreme ultraviolet emission from high-density Xe plasmas

Sasaki, Akira; Nishihara, Katsunobu*; Murakami, Masakatsu*; Koike, Fumihiro*; Kagawa, Takashi*; Nishikawa, Takeshi*; Fujima, Kazumi*; Kawamura, Toru*; Furukawa, Hiroyuki*

Applied Physics Letters, 85(24), p.5857 - 5859, 2004/12

 Times Cited Count:41 Percentile:79.35(Physics, Applied)

no abstracts in English

Journal Articles

Theoretical simulation of extreme UV radiation source for lithography

Fujima, Kazumi*; Nishihara, Katsunobu*; Kawamura, Toru*; Furukawa, Hiroyuki*; Kagawa, Takashi*; Koike, Fumihiro*; More, R.*; Murakami, Masakatsu*; Nishikawa, Takeshi*; Sasaki, Akira; et al.

Emerging Lithographic Technologies VIII, Proceedings of SPIE Vol.5374, p.405 - 412, 2004/00

no abstracts in English

Oral presentation

Radiative properties of Xe and Sn plasmas

Sasaki, Akira; Nishihara, Katsunobu*; Sunahara, Atsushi*; Maehara, Hiroaki*; Nishikawa, Takeshi*; Koike, Fumihiro*; Kagawa, Takashi*; Tanuma, Hajime*

no journal, , 

no abstracts in English

44 (Records 1-20 displayed on this page)