Y. Tao

Nanjing Agricultural University

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M. S. Tillack

General Atomics (United States)

R. Burdt

University of Missouri

F. Najmabadi

University of California, San Diego

K. Sequoia

General Atomics (United States)

S. Yuspeh

University of California, San Diego

Shinsuke Fujioka

Osaka University

N. Miyanaga

Osaka University

Katsunobu Nishihara

Osaka University

Yasukazu Izawa

Panasonic (Japan)

H. Nishimura

Yamato University

Cooperative Institutions

Osaka University

Institute for Laser Technology

University of California, San Diego

Nanjing Agricultural University

Tohoku University

Lawrence Livermore National Laboratory

The University of Tokyo

Kyoto University

National Institute for Fusion Science

Japan Science and Technology Agency

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Mass-limited Sn target irradiated by dual laser pulses for an extreme ultraviolet lithography source

Optics Letters (2007)

Y. Tao M. S. Tillack S. S. Harilal K. Sequoia R. Burdt

A thin Sn film was investigated as a mass-limited target for an extreme ultraviolet (EUV) lithography source. It was found that those energetic ions that are intrinsic with the mass-limited Sn target could be efficiently mitigated by introducing a low-energy prepulse. High in-band conversion efficiency from a laser to 13.5 nm EUV light could be obtained using an Sn film with a thickness down to 30 nm when irradiated by dual laser pulses. It was shown that the combination of dual pulse and inert Ar gas could fully mitigate ions with a low ambient pressure nearly without the penalty of the absorption of the EUV light.

Extreme Ultraviolet Lithography

Extreme ultraviolet

Ultraviolet

10.1364/ol.32.001338

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Citations (8)

Development of EUV light source by laser-produced plasma

Journal de Physique IV (Proceedings) (2006)

Yasukazu Izawa N. Miyanaga H. Nishimura Shinsuke Fujioka T. Aota

Extreme Ultraviolet Lithography

10.1051/jp4:2006133237

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Citations (1)

EUV and particle generations from laser-irradiated solid- and low-density targets

Journal de Physique IV (Proceedings) (2006)

H. Nishimura Shinsuke Fujioka T. Okuno Y. Tao Nasuo Ueda

Extreme Ultraviolet Lithography

Extreme ultraviolet

Opacity

Ultraviolet

Particle (ecology)

10.1051/jp4:2006133243

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Citations (1)

Spectral Control of Emission from Tin Doped Targets for Extreme Ultraviolet Lithography - eScholarship

S. S. Harilal B O'Shay M. S. Tillack Y. Tao R. R. Paguio

We have investigated the unresolved transition array (UTA) emission around 13.5 nm from solid density tin and tin doped foam targets. Extreme ultraviolet (EUV) spectral measurements were made in the wavelength region 11–17 nm using a transmission grating spectrograph and the EUV in-band conversion efficiency was measured using an absolutely calibrated EUV calorimeter. The aim of this work was to optimize the UTA emission with the proper density of tin dopant in low-Z foam targets. The addition of tin as an impurity leads to a reduction in the plasma continuum and narrowing of the UTA compared with fully dense tin targets. Our studies indicate that the required percentage of tin for obtaining bright in-band spectral emission is less than 1%.

Extreme Ultraviolet Lithography

Extreme ultraviolet

Ultraviolet

Source

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Efficient 13.5nm extreme ultraviolet emission from Sn plasma irradiated by a long CO2 laser pulse

Applied Physics Letters (2008)

Y. Tao M. S. Tillack K. Sequoia R. Burdt S. Yuspeh

The effect of pulse duration on in-band (2% bandwidth) conversion efficiency (CE) from a CO2 laser to 13.5nm extreme ultraviolet (EUV) light was investigated for Sn plasma. It was found that high in-band CE, 2.6%, is consistently obtained using a CO2 laser with pulse durations from 25to110ns. Employing a long pulse, for example, 110ns, in a CO2 laser system used in an EUV lithography source could make the system significantly more efficient, simpler, and cheaper as compared to that using a short pulse of 25ns or shorter.

Extreme Ultraviolet Lithography

Extreme ultraviolet

Pulse duration

Ultraviolet

10.1063/1.2951595

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Citations (47)

Progress in understanding of laser-produced plasmas for EUV source

N. Miyanaga Kazumi Fujima Shinsuke Fujioka Yasushi Fujimoto H. Fujita

Our research aims at the physical understanding of laser-produced plasma (LPP) as an EUV source for lithography. To provide a database of EUV source this comprehensive research includes high performance laser development, target fabrication, plasma experiments, theory and simulations. We will report present progress of each subject, particularly recent experimental results of Sn and SnO/sub 2/ targets and comparison with computer simulations.

Extreme Ultraviolet Lithography

10.1109/leos.2003.1251755

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Citations (0)

Spectral control of emissions from tin doped targets for extreme ultraviolet lithography

Journal of Physics D Applied Physics (2006)

S. S. Harilal B O'Shay M. S. Tillack Y. Tao R. R. Paguio

Extreme Ultraviolet Lithography

Ultraviolet

Extreme ultraviolet

10.1088/0022-3727/39/3/010

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Citations (60)

Effect of shockwave-induced density jump on laser plasma interactions in low-pressure ambient air

Journal of Physics D Applied Physics (2006)

Y. Tao M. S. Tillack S. S. Harilal K. Sequoia B O'Shay

The dynamics of laser-produced plasma (LPP) and its shockwave-induced density jump (SIDJ) were investigated in low-pressure ambient air during the laser pulse using an optical interferometer. A tiny SIDJ could be observed clearly in ambient air with pressure as low as 3 Torr even during the rising edge of a 7 ns laser pulse. It was shown that the density jump and ionization could seed laser-induced ambient air breakdown at a relatively low pressure, which could significantly reduce laser energy deposited in the LPP. The ionization of the density jump was confirmed by dynamic emission imaging.

10.1088/0022-3727/39/18/014

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Citations (32)

Investigation on the interaction of long duration Nd:YAG laser pulse with Sn plasma for an EUV metrology source

Proceedings of SPIE, the International Society for Optical Engineering/Proceedings of SPIE (2011)

Y. Tao Yoshifumi Ueno S. Yuspeh R. Burdt M. S. Tillack

The effect of pulse duration of Nd:YAG laser with wavelength of 1.064 μm on the generation of 13.5 nm extreme ultraviolet (EUV) emission and ions was investigated. It was found that almost constant in-band (2 % bandwidth) conversion efficiency (CE) is obtained from Sn plasmas irradiated with Nd:YAG laser pulse with durations from 0.13 to 30 ns. It was also noted that Sn ions kinetic energy generated with a 30 ns laser pulse is much less than those with 0.13 and 7 ns laser pulses. The measurement on the narrow-band EUV imaging showed that EUV source size strongly depends on laser intensity instead of pulse duration and small EUV size is still possible with laser pulse duration as long as 30 ns. The key reason for the constant CE and the still small EUV source size obtained with long laser pulse duration comes from the small laser focal spot employed in the present experiment, i.e., 40 μm (FWHM). This research shows that an efficient and bright EUV source is feasible with a long pulse duration Nd:YAG laser. The lower peak intensity of EUV emission due to the long pulse duration makes the EUV source more suitable for EUV metrology.

Extreme Ultraviolet Lithography

Extreme ultraviolet

Pulse duration

10.1117/12.881223

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Citations (5)

Study on EUV emission properties of laser-produced plasma at ILE, Osaka

Proceedings of SPIE, the International Society for Optical Engineering/Proceedings of SPIE (2004)

M. Nakai Hiroaki Nishimura K. Shigemori N. Miyanaga T. Norimatsu

A new research project on extreme ultraviolet (EUV) source development has just been started at the Institute of Laser Engineering, Osaka University. The main task of this project is to find a scientific basis for generating efficient, high-quality, high power EUV plasma source for semiconductor industry. A set of experimental data is to be provided to develop a detailed atomic model included in computer code through experiments using GEKKO-XII high power laser and smaller but high-repetitive lasers. Optimum conditions for efficient EUV generation will be investigated by changing properties of lasers and targets. As the first step of the experiments, spherical solid tin and tin-oxide targets were illuminated uniformly with twelve beams from the GEKKO XII. It has been confirmed that maximum conversion efficiency into 13.5 nm EUV light is achieved at illumination intensity less than 2 x 10¹¹ W/cm². No significant difference is found between laser wavelengths of one μm and a half μm. Density structure of the laser-irradiated surface of a planar tin target has beem measured experimentally at 10¹² W/cm² to show formation of double ablation structure with density plateau by thermal radiation transport. An opacity experiment has just been initiated.

Extreme Ultraviolet Lithography

Extreme ultraviolet

Opacity

10.1117/12.504166

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Citations (7)