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Volume 36, Issue 11
Displaying 1-12 of 12 articles from this issue
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Koichi TOYODA2008 Volume 36 Issue 11 Pages 672
Published: November 15, 2008
Released on J-STAGE: March 26, 2014
JOURNAL FREE ACCESSDownload PDF (184K) -
Iwao NISHIYAMA2008 Volume 36 Issue 11 Pages 673-683
Published: November 15, 2008
Released on J-STAGE: March 26, 2014
JOURNAL FREE ACCESSExtreme-ultraviolet lithography (EUVL) provides high resolution using 13.5nm light. It is the most promising technology for fabricating semiconductor devices at the hp 32-nm scale and smaller. However the short wavelength light causes some technical issues, such as high-power EUV light source, precise aspherical multilayered mirror, precise exposure system, low defect multi-layered mirror, high resolution resist and so on. The technology development is advanced in the project in each worldwide base. As a result, it has been advanced greatly in these ten years. Now, full field EUVL exposure tools are available, and semiconductor devices are demonstrated to be fabricated. In this article, we describe the current technical progress in EUV Lithography.View full abstractDownload PDF (18813K) -
Akira SUMITANI2008 Volume 36 Issue 11 Pages 684-689
Published: November 15, 2008
Released on J-STAGE: March 26, 2014
JOURNAL FREE ACCESSThe development of a reliable high power EUV light source is one of the major technical challenges for the implementation of EUV lithography. A review is given on the development of a laser produced plasma light source for high volume manufacturing (HVM) EUV lithography. An LPP source is the most promising ap-proach to generate the required in-band EUV power level. Our source is based on a high power, high repetition rate CO2 laser system, a tin target and magnetic plasma guiding for collector mirror lifetime enhancement.EUV in-band power equivalent to 60W at intermediate focus was produced by irradiating a tin rotating plate with 6kW laser power. Collector mirror life can be extended by using droplet target and magnetic plasma guiding. The effectiveness of this approach is examined by monitoring the motion of fast Sn ion in a large vacuum chamber.View full abstractDownload PDF (8872K) -
Katsunobu NISHIHARA, Atsushi SUNAHARA, Akira SASAKI, Hajime TANUMA, Fu ...2008 Volume 36 Issue 11 Pages 690-699
Published: November 15, 2008
Released on J-STAGE: March 26, 2014
JOURNAL FREE ACCESSExtreme ultraviolet (EUV) radiation from laser produced plasmas (LPP) has been theoretically studied as a light source for lithography in mass-production of the next generation semiconductor devices. One of the critical issues for realization of a LPP-EUV light source is the conversion efficiency (CE) from incident laser power to EUV radiation of 13.5nm wavelength (within 2% bandwidth). From an atomic physical point of view, we explain the reason why tin has been chosen as the most suitable radiation material compared with xenon and lithium. We also present a power balance model, which can be used for the optimization of laser and target conditions to obtain high CE. We propose a double-pulse irradiation scheme for high CE using a carbon dioxides laser and a droplet target. Using our benchmarked numerical simulation code, we show a possibility to obtain CE up to 5-7%, much higher presently achieved.View full abstractDownload PDF (2595K) -
Hiroaki NISHIMURA, Shinsuke FUJIOKA, Yoshinori SHIMADA2008 Volume 36 Issue 11 Pages 700-707
Published: November 15, 2008
Released on J-STAGE: March 26, 2014
JOURNAL FREE ACCESSProperties of extreme ultraviolet (EUV) emission from laser generated Tin plasma were very thoroughly studied to provide experimental database for theoretical modeling and benchmarking of radiation hydrodynamic code dedicated for the EUV source research. EUV emission spectra and conversion efficiencies, defined as fraction of drive laser energy allotted for EUV ligh involved in a 2% bandwidth at 13.5nm in wavelength (i. e., inband-component) were quantitatively investigated given as a function of laser intensity, laser wavelength, target densities, and target shapes. A minimum mass target, involving a least number but sufficiently enough Tin-atoms to generate EUV light, is suggested to mitigate debris from the EUV source. A technical guideline to diminish kinetic energy of ion debris and the out-of band emission is also discussed.View full abstractDownload PDF (7598K) -
Hisanori FUJITA, Hiroshi KOMORI2008 Volume 36 Issue 11 Pages 708-714
Published: November 15, 2008
Released on J-STAGE: March 26, 2014
JOURNAL FREE ACCESSHigh repetition and high power laser development is one of the important subjects for the realization of a practical EUV light source for microlithography using 13.5 nm. This paper presents advances in Nd: YAG laser and CO2 laser development for EUV source application at Osaka University and EUVA, respectively. An average laser power of 5.2k W at 100k Hz repetition rate with 10 ns pulse width was achieved from a Nd: YAG laser system developed at Osaka University, while an average laser power of 13k W at 100k Hz repetition rate with 20 ns pulse width was achieved from a short pulse CO2 MOPA (Master Oscillator Power Amplifier) system developed at EUVA.View full abstractDownload PDF (4781K) -
Sho AMANO, Akihisa NAGANO, Takahiro INOUE, Shuji MIYAMOTO, Takayasu MO ...2008 Volume 36 Issue 11 Pages 715-720
Published: November 15, 2008
Released on J-STAGE: March 26, 2014
JOURNAL FREE ACCESSAs for deposition-free-targets, cryogenic Xe and Li targets of laser- produced-plasma have been studied for extreme ultraviolet (EUV) light sources. A fast rotating cryogenic drum system, which can continuously supply a solid Xe target, has been developed. It successfully generated about 1 W of EUV power by continuous irradiation of Nd: YAG slab laser at 320 pps, with a maximum conversion efficiency of 0.9%. Experimental results for the Xe target of the double-pulse and short-wavelength irradiation have also been reported. In addition, a new Li target using a forced-recombination scheme was demonstrated. It was found that the maximum conversion efficiency was 2.3% with a laser irradiation of 532nm in Li planar targets. By using both direct EUV emissions and forced-recombination emissions, higher efficiency can be achieved.View full abstractDownload PDF (4286K) -
Daisuke NAKAMURA, Tomoya AKIYAMA, Akihiko TAKAHASHI, Tatsuo OKADA2008 Volume 36 Issue 11 Pages 721-725
Published: November 15, 2008
Released on J-STAGE: March 26, 2014
JOURNAL FREE ACCESSThe dynamics of debris from laser-produced tin (Sn) plasma was investigated in order to establish the guideline for a practical extreme ultraviolet (EUV) lithography source.A comparative investigation on the emission characteristics of debris from CO2 laser-produced Sn plasma and Nd: YAG laser-produced Sn plasma was investigated.The results showed higher ion kinetic energy and lower particle emission for the CO2 laser than the Nd: YAG laser for the same laser energy.The kinetic behaviors of the Sn atoms and of the dense particles from Sn droplet target irradiated by double pulses from the Nd: YAG laser and the CO2 laser were also investigated by the laser-induced fluorescence imaging method and a high-speed imaging, respectively.After the pre-pulse irradiation of the Nd: YAG laser, the Sn atoms were ejected in all direction from the target and the irradiated target by the pre-pulse was almost disappeared by main-pulse irradiation.View full abstractDownload PDF (7968K) -
Masanori KAKU, Shoichi KUBODERA2008 Volume 36 Issue 11 Pages 726-730
Published: November 15, 2008
Released on J-STAGE: March 26, 2014
JOURNAL FREE ACCESSebris characteristics and theireduction have been investigated for a laser-produced plasma extreme ultraviolet source by using a colloidal jet/droplet target containing tin dioxide nanoparticles. The amount of deposited debris on a silicon witness plate was determined by totalaser energy irradiated onto the target. Double laser pulse irradiation was not effective for deposited debris reduction. Incontrast, in situ low-temperature heating of the witness plate was effective inreducing the amount of deposited debris. Room-temperature photon processing using an incoherent vacuum ultraviolet excimer lamp at 126 nm deoxidized a deposited tin oxide layerView full abstractDownload PDF (896K) -
Etsuo FUJIWARA2008 Volume 36 Issue 11 Pages 731-735
Published: November 15, 2008
Released on J-STAGE: March 26, 2014
JOURNAL FREE ACCESSA novel droplet generator equipped with flow-control has been developed for the formation of molten tin droplets. The piston with a piezoelectric crystal enables us to change the flow resistance in a narrow gap region between a liquid vessel and a nozzle, resulting in the variation of the flow velocity at a high repetition rate. The formation of tin droplets using this generator was demonstrated in a wide frequency region from 16 to 59 k Hz using a 50μm nozzle, which lies with the range of 3.9<λId<14. The separation of the piezoelectric crystal and the nozzle in this droplet generator is quite suitable for high-temperature liquids such as molten tin and for harsh environments such as those in vacuum. A flight control of water droplets was also demonstrated by electrifying the droplets.View full abstractDownload PDF (7880K) -
Yoshinori SHIMADA, Shinsuke MAEDA, Shinsuke FUJIOKA, Atsushi SUNAHARA, ...2008 Volume 36 Issue 11 Pages 736-741
Published: November 15, 2008
Released on J-STAGE: March 26, 2014
JOURNAL FREE ACCESSExtreme ultraviolet (EUV) emissions from a laser-irradiated, low-density flying target were thoroughly investigated. The target was produced by irradiating a 1-μm-thick solid tin layer with a weak laser pulse that passes through an optically transparent substrate. This irradiation causes the tin overcoat layer todisintegrate into a mixture of plasmas, gases, clusters, and fine particles. The center-of-mass velocity and angular spread of the target were observed to be 0.93km/s and 6-8 degrees, respectively. EUV emission spectra, at around 13.5nm, from the target driven with a CO2 laser pulse were narrower than those from a solid tin irradiated with a Nd: YAG laser beam, and the conversion efficiency at 13.5nm in a 2% bandwidth became as high as 2.8% at a laser intensity of 1010W/cm2.View full abstractDownload PDF (8504K) -
Hiroyuki FURUKAWA2008 Volume 36 Issue 11 Pages 742-746
Published: November 15, 2008
Released on J-STAGE: March 26, 2014
JOURNAL FREE ACCESSCombined Laser Ablation Fluid RAdiation simulation Code (LAFRAC) is developed for estimation of debris generation from Laser-produced tin EUV light sources. Debris consists mainly of neutral particles, which cannot be controlled by electric and/or magnetic forces. Therefore, estimations on generation of neutral par ticles and mitigation of them is very important. In LAFRAC, phase transitions from solid to liquid and liquid to gas are modeled by improved Anisimov formula. The formation of clusters in the ablated plume (phase transition from gas to liquid) is evaluated by a new model based on Luk'yanchuck-Zeldovich-Raizer model. The new model is written for plane symmetry with arbitaly profiles. Theoretical estimations on debris generations and comparison between CO2 and Nd: YAG laser cases are performed. In the case of using CO2 laser and tin targets, debris generation is reduced compared with the case of using Nd: YAG laser.View full abstractDownload PDF (759K)
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