Takei, Satoshi*; Oshima, Akihiro*; Oyama, Tomoko; Ito, Kenta*; Sugahara, Kigen*; Kashiwakura, Miki*; Kozawa, Takahiro*; Tagawa, Seiichi*; Hanabata, Makoto*
Japanese Journal of Applied Physics, 53(11), p.116505_1 - 116505_7, 2014/11
The application of natural linear polysaccharide to green resists was demonstrated for electron beam (EB) and extreme-ultraviolet (EUV) lithography. Because of the water solubility of natural polysaccharides, the water spin-coating and water-developable processes realize an environmentally friendly manufacturing process for next-generation electronic devices. The developed green resist with a weight-average molecular weight of 83,000 and 70 mol % hydroxyl groups was found to have acceptable properties such as spin-coat ability on 200 mm wafers, pillar patterns of 100-400 nm with a high EB sensitivity of 10 C/cm, etch selectivity with a silicon-based middle layer in CF plasma treatment, and high prediction sensitivity to EUV region.
Takei, Satoshi*; Oshima, Akihiro*; Ichikawa, Takumi*; Sekiguchi, Atsushi*; Kashiwakura, Miki*; Kozawa, Takahiro*; Tagawa, Seiichi*; Oyama, Tomoko; Ito, Shoji*; Miyasaka, Hiroshi*
Microelectronic Engineering, 122, p.70 - 76, 2014/06
Biomass-derived branched sugar resist material was developed for environmentally-friendly electron beam lithography (EBL). The developed resist enables organic solvent-free water-developable process. The resist performance was evaluated using 75 keV EBL system. Lines of 50-200 nm were fabricated with high sensitivity of 7 C/cm. The resist is developable in pure water at 23 C for 60 s, and it has acceptable CF etch selectivity.
Oyama, Tomoko; Nakamura, Hirotaka*; Oshima, Akihiro*; Washio, Masakazu*; Tagawa, Seiichi*
Applied Physics Express, 7(3), p.036501_1 - 036501_3, 2014/03
A chlorinated polymer ZEP is a main-chain scission type (positive-tone) high-sensitivity resist. However, we found that ZEP changes to negative-tone with a high dose of electron beam irradiation. The sensitivities to a 100 kV electron beam as a dual-tone are evaluated with various developers. Owing to different solvation strengths, the resist sensitivity varied with different developers in the positive-tone region. On the other hand, it was found that the threshold dose for the positive-negative inversion is independent of the developer. According to an analysis using X-ray photoelectron spectroscopy and NMR spectroscopy, we found that the amount of chlorine atoms and terminal double bonds generated by chain scission determines the threshold of the P-N inversion. This result provides important information for possible ZEP applications such as a dual-tone resist.
Hosaka, Yuji*; Oyama, Tomoko; Oshima, Akihiro*; Enomoto, Satoshi*; Washio, Masakazu*; Tagawa, Seiichi*
Journal of Photopolymer Science and Technology, 26(6), p.745 - 750, 2013/12
ZEP520A is one of the most popular positive electron beam (EB) resists used in research and photomask fabrication owing to its excellent properties. Herein, EB-induced initial reactions of ZEP520A were investigated via pulse radiolysis (EB energy: 28 MeV, time resolution: 10 ns). Dissociative electron attachment and formation of a charge transfer complex were definitive contributing factors to the efficient degradation of ZEP520A. Furthermore, products induced by direct ionization of ZEP520A were observed in a highly concentrated ZEP520A solution in tetrahydrofuran, suggesting that initial reactions in the ZEP520A solid film that are induced only by direct ionization could be simulated via pulse radiolysis in specific solutions.
Oyama, Tomoko; Hinata, Toru*; Nagasawa, Naotsugu; Oshima, Akihiro*; Washio, Masakazu*; Tagawa, Seiichi*; Taguchi, Mitsumasa
Applied Physics Letters, 103(16), p.163105_1 - 163105_4, 2013/10
Micro/nanofabrication of biocompatible and biodegradable poly(-lactic acid) (PLLA) was evaluated using focused Ga ion beam direct etching. The fabrication performance was determined with different ion fluences and fluxes. It was found that the etching speed and fabrication accuracy were affected by irradiation-induced heat because the resistance of PLLA to thermal deformation is decreased when above its glass transition temperature (approximately 60C). By controlling the irradiation conditions, controlled micro/nanostructures of PLLA were fabricated, such as holes (80 nm) and alphabets (width: 100 nm). Moreover, focused ion beam (FIB)-irradiated surfaces were analyzed using micro-area X-ray photoelectron spectroscopy. Owing to reactions such as the physical sputtering of atoms and radiation-induced decomposition, PLLA was gradually carbonized with increasing C=C bonds expected to have good cell attachment properties.
Oyama, Tomoko; Oshima, Akihiro*; Washio, Masakazu*; Tagawa, Seiichi*
Journal of Vacuum Science and Technology B, 31(4), p.041604_1 - 041604_5, 2013/07
Okubo, Satoshi*; Nagasawa, Naotsugu; Kobayashi, Akinobu*; Oyama, Tomoko*; Taguchi, Mitsumasa; Oshima, Akihiro*; Tagawa, Seiichi*; Washio, Masakazu*
Applied Physics Express, 5(2), p.027303_1 - 027303_3, 2012/02
Electron beam nanoimprint lithography was proposed for fabricating the micro-/nanostructures of cross-linked poly(-lactic acid) (RX-PLLA). PLLA with triallyl isocyanurate (TAIC) solutions were dropped on the Si-molds fabricated by the conventional EB lithography technique. PLLA/TAIC on Si-molds were imprinted and cross-linked with doses from 10 to 500 kGy at room temperature under vacuum. The micro-/nanostructures of RX-PLLA were successfully obtained with high accuracy. Hence, it was found that the imprinted structures of RX-PLLA (100 kGy irradiation) show low line edge roughness and high thermal durability at 120 C.
Okubo, Satoshi*; Takahashi, Tomohiro*; Takasawa, Yuya*; Gowa, Tomoko*; Sasaki, Takashi*; Nagasawa, Naotsugu; Tamada, Masao; Oshima, Akihiro*; Tagawa, Seiichi*; Washio, Masakazu*
Journal of Photopolymer Science and Technology, 23(3), p.393 - 397, 2010/11
Microfabrication of biodegradable polymers such as poly(butylene succinate--adipate) (PBSA) and poly(-caprolactone) (PCL) were demonstrated using focused ion beam (FIB) with maskless direct etching. As the result, the micro structures of PBSA and PCL were obtained. The etching depth of both PBSA and PCL were increased with increasing FIB fluence, and the etching rates were estimated to be about 1.3 10 m/(ions cm) and 1.2 10 m/(ions cm), respectively. Moreover, very thin films of PBSA and PCL were made by spin-coating method. The thicknesses of the spin-coated samples were about 200 nm, and the surface roughness was less than 10 nm (RMS). The fine structures such as micro-gear of PBSA and PCL were obtained without solid debris. The line width of the fabricated structure was about 250 nm.
Belloni, J.*; Crowell, R. A.*; Katsumura, Yosuke; Lin, M.; Marignier, J. L.*; Mostafavi, M.*; Muroya, Yusa*; Saeki, Akinori*; Tagawa, Seiichi*; Yoshida, Yoichi*; et al.
Recent Trends in Radiation Chemistry, p.121 - 160, 2010/05
In this review, we summarized development and application of highly time resolved spectroscopy system in order to measure radiation induced fast phenomena together with current status of the systems in the world.
Sakuraba, Naotoshi; Numata, Masami; Komiya, Tomokazu; Ichise, Kenichi; Nishi, Masahiro; Tomita, Takeshi; Usami, Koji; Endo, Shinya; Miyata, Seiichi; Kurosawa, Tatsuya; et al.
JAEA-Technology 2009-071, 34 Pages, 2010/03
As a part of maintenance technology of a large-sized glove box for handling of TRU nuclides, we developed replacement technology for front acrylic panels using the bag-in/bag-out method and applied this technology to replace the deteriorated front acrylic panels at Waste Safety Testing Facility (WASTEF) in Nuclear Science Research Institute of Japan Atomic Energy Agency (JAEA). As a consequence, we could safely replace the front acrylic panels under the condition of continuous negative pressure only with partial decontamination of the glove box. We also demonstrated that the present technology is highly effective in points of safety, workability and cost as compared to the usual replacement technology for front acrylic panels of a glove box, where workers in an air-line suit replace directly the front acrylic panels in a green house.
Yang, J.*; Kondo, Takafumi*; Norizawa, Kimihiro*; Nagaishi, Ryuji; Taguchi, Mitsumasa; Takahashi, Kenji*; Kato, Ryuji*; Anishchik, S. V.*; Yoshida, Yoichi*; Tagawa, Seiichi*
Radiation Physics and Chemistry, 77(10-12), p.1233 - 1238, 2008/10
First observation of picosecond dynamics in ionic liquid of DEMMA-TFSI in radiation chemistry was reported. It is found that the electron produced by ionization is solvated to full solvation in ionic liquid with a rate constant of 3.910 s. The yield of solvated electrons in picosecond time region is 1.210 mol J. The dry electron in ionic liquid reacts rapidly with biphenyl and pyrene with a rate constant of 3.8 to 7.910 L mol s. The geminate ion recombination in n-dodecane and n-hexane was also observed by monitoring the transient absorptions at 523 nm.
Seki, Shuhei*; Tsukuda, Satoshi*; Tagawa, Seiichi*; Sugimoto, Masaki; Sato, Takahiro; Oikawa, Masakazu*; Sakai, Takuro
JAEA-Review 2006-042, JAEA Takasaki Annual Report 2005, P. 145, 2007/02
no abstracts in English
Tsukuda, Satoshi*; Seki, Shu*; Sugimoto, Masaki; Tagawa, Seiichi*
Journal of Physical Chemistry B, 110(39), p.19319 - 19322, 2006/10
no abstracts in English
Seki, Shu*; Tsukuda, Satoshi*; Tagawa, Seiichi*; Sugimoto, Masaki
Macromolecules, 39(21), p.7446 - 7450, 2006/10
no abstracts in English
Yoshida, Yoichi*; Yang, J.*; Kondo, Takafumi*; Seki, Shuhei*; Kozawa, Takahiro*; Tagawa, Seiichi*; Shibata, Hiromi*; Taguchi, Mitsumasa; Kojima, Takuji; Namba, Hideki
JAEA-Review 2005-001, TIARA Annual Report 2004, p.183 - 185, 2006/01
A heavy-ion-pulse radiolysis technology was developed using a single-photon-counting system. In the system, the ion beam was injected a thin scintillator before irradiating the sample. The light emitted from the scintillator by the ion irradiation was used as analyzing source to detect the absorption of primary species in water. Measurement of time-dependent absorption of hydrated electrons in water was achieved using the system, which demonstrates the usefulness of this technique.
Yoshida, Yoichi*; Yang, J.*; Saeki, Akinori*; Tagawa, Seiichi*; Shibata, Hiromi*; Namba, Hideki; Kojima, Takuji; Taguchi, Mitsumasa
JAERI-Review 2004-025, TIARA Annual Report 2003, p.143 - 144, 2004/11
no abstracts in English
Tsukuda, Satoshi*; Seki, Shuhei*; Tagawa, Seiichi*; Sugimoto, Masaki; Idesaki, Akira; Tanaka, Shigeru; Oshima, Akihiro*
Journal of Physical Chemistry B, 108(11), p.3407 - 3409, 2004/03
Nano-wire formation in Si-based polymer thin films using a heavy ion beam is discussed in terms of energy density deposition along ion tracks. Gelation of the polymer along the ion track results in cross-linking to produce nano-wires with size and number density controllable by selecting appropriate ion beam characteristics and polymer materials. Ion bombardment of polycarbosilane (PCS), PCS-polyvinylsilane blend polymer, and polymethylphenylsilane produces nano-wires with radii of 30 nm depending on the type of ion beam. The difference in size is shown to be related to the efficiency of the cross-linking reaction considering the deposited energy distribution along the ion tracks.
Yoshida, Yoichi*; Yang, J.*; Seki, Shuhei*; Saeki, Akinori*; Tagawa, Seiichi*; Shibata, Hiromi*; Taguchi, Mitsumasa; Kojima, Takuji; Namba, Hideki
JAERI-Review 2003-033, TIARA Annual Report 2002, p.145 - 146, 2003/11
no abstracts in English
Yanagisawa, Kazuaki; Kume, Tamikazu; Makuuchi, Keizo; Tagawa, Seiichi*; Chino, Mitsuo*; Inoue, Tomio*; Takehisa, Masaaki*; Hagiwara, Miyuki*; Shimizu, Masahiko*
Journal of Nuclear Science and Technology, 39(10), p.1120 - 1124, 2002/10
no abstracts in English