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Hirotaka Ejima, Ayako Sakurai, Naoko Yoshie
2017 Volume 30 Issue 3 Pages
259-264
Published: June 26, 2017
Released on J-STAGE: August 10, 2017
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We studied the alignment of gold nanorods (Au NRs) in polymer blends that were directionally solidified in the crystallizable organic solvent trichlorobenzene (TCB). The polymer blends/Au NRs were dissolved or dispersed in TCB at 80
oC between two glass plates. By cooling the sample, the polymer blends and Au NRs were directionally solidified as the liquid TCB transformed into large single crystals. With poly(3-hexylthiophene-2,5-diyl)/polyethylene glycol (P3HT/PEG) used as the polymer blend pair, PEG-modified Au NRs predominantly localized inside the PEG domains of the solidified films. In contrast, with a P3HT/poly(2-vinylpyridine) blend, PEG-modified Au NRs mostly localized at the interface between the polymers. These results show that directional solidification in crystallizable organic solvents is an effective one-step process for the alignment of Au NRs in polymer matrices.
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Masao Kamimura, Yuto Yano, Shuhei Kuraoka, Satoru Suyari ...
2017 Volume 30 Issue 3 Pages
265-270
Published: June 26, 2017
Released on J-STAGE: August 10, 2017
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In this study, upconversion (UC) photopolymerization of non-polar polystyrene (PSt) shells on rare-earth doped ceramic nanophosphors (RED-CNPs) was investigated to improve the optical properties. The PSt layer was prepared on rare-earth doped NaYF
4 NP surfaces by UC photopolymerization under 980 nm near-infrared (NIR) irradiation. The obtained PSt-modified NaYF
4 NPs are promising candidates for fluorescence imaging and as nanothermometry agents.
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Kiwamu Terada, Masahiro Furutani, Koji Arimitsu
2017 Volume 30 Issue 3 Pages
271-273
Published: June 26, 2017
Released on J-STAGE: August 10, 2017
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Most of the photopatterning materials based on epoxy resins are utilizing photoacid generators (PAGs) which generate superacids as catalysts. They have been used for high aspect ratio photoresists in the fabrication of MEMS devices. However, there is a drawback that the acidic species from PAGs will induce metal corrosion. One of the approach to overcome this problem is the use of photobase generators (PBGs) because organic bases would induce no corrosion. Although there is a large number of investigation of PBGs in past time, only few articles have mentioned photoreactive materials relying on PBGs due to its low photosensitivity. We report here highly sensitive photopatterning materials comprising PBG and an epoxy resin bearing carboxylic acid groups. As a result, the photopatterning material showed higher photosensitivity when compared to conventional epoxy resin systems. We obtained high photosensitivity (up to 900 mJ/cm
2), high resolution (10 μm line and space) patterning materials in thin films of 10 μm in thickness.
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Naoto Sugino, Satoshi Takei, Shinya Nakajima, Makoto Hanabata, Takao ...
2017 Volume 30 Issue 3 Pages
275-280
Published: June 26, 2017
Released on J-STAGE: August 10, 2017
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In recent years, optical lithography technology used for micro fabrication of electronic devices, semiconductors, etc. has continues to advance for the purpose of cost reduction and improvement. However, plenty of transfer failure caused by air entrained when pressing the mold against the material to be transferred or gas generated from the resist material were reported in the nanoimprint process. Therefore, in order to develop a novel template material with gas permeability, chemical modification of crystalline cellulose with different viscosity and molecular weight was evaluated the physical properties in this study. By using this gas permeable template material as a mold, a transfer material containing acetone as a volatile solvent was molded. As a result, a shape of 5 μm was transferred to be the material containing a volatile solvent, and no defect due to a gas generated from a volatile solvent was confirmed. This gas permeable template material can be expected to reduce transfer defects in imprints and can be said to have a possibility to broaden the selectivity of resist materials.
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Kazuma Takamori, Takashi Nishiyama, Eriko Sato, Hideo H ...
2017 Volume 30 Issue 3 Pages
281-284
Published: June 26, 2017
Released on J-STAGE: August 10, 2017
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Three-component chemically amplified photoresists which are consisted of a base resin, a photo acid generator and a dissolution inhibitor are promising because the high sensitivity and the high resolution can be satisfied at the same time. We studied about the dissolution promotion effect of hydroquinone (HQ) in the exposed area. HQ is a model compound of the photo induced product of the dissolution inhibitor. We disclosed that HQ depressed a glass transition temperature (
Tg) of the base resin and the sensitivity was improved by enhancing the dissolution rate in the exposed area. It is expected that the dissolution rate was promoted when the post exposure bake temperature exceeded
Tg because the acid diffuse more easily.
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Takashi Nishiyama, Kohei Matsuura, Eriko Sato, Noritsugu Kom ...
2017 Volume 30 Issue 3 Pages
285-289
Published: June 26, 2017
Released on J-STAGE: August 10, 2017
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Polyethylene glycol (PEG) in aqueous solution was decomposed by treating O
3 microbubbles and O
3 water. The molecular weight of PEG treated with O
3 microbubbles became lower, and the PEG degradation was enhanced in alkaline condition. PEG in aqueous solution was efficiently decomposed by reactive oxygen species generated by O
3 decomposition, and O
3 microbubbles promoted the O
3 decomposition in the interface of O
3 gas and surrounding water in which OH anion localized. PEG in aqueous solution was decomposed to inorganic oxygen by advanced oxidation process (AOP) of O
3 microbubbles and H
2O
2, and the reduction rate of total organic carbon (TOC) was over 70%.
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Tomosumi Kamimura, Hirouki Kuramae, Takayuki Yamashiro, Kosuke Nu ...
2017 Volume 30 Issue 3 Pages
291-295
Published: June 26, 2017
Released on J-STAGE: August 10, 2017
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Resist removal phenomenon with laser irradiation was analyzed by using a finite element (FE) method. Laser irradiation in the water can improve the resist removal effect as compared with that of normal atmosphere irradiation. A two-dimensional (2-D) micro-FE model was constructed based on the boundary surface between the Si wafer, resist and water during laser radiation. In the normal atmosphere, any effective stress did not occur along the x-axis direction in the resist. In contrast, for the laser irradiation in the water, large compressive stress was confirmed along the x-axis direction in the resist. This compressive stress in the resist is thought to improve the resist removal efficiency.
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Masashi Yamamoto, Tomohiro Shiroi, Shiro Nagaoka, Tomokazu ...
2017 Volume 30 Issue 3 Pages
297-301
Published: June 26, 2017
Released on J-STAGE: August 10, 2017
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Photoresists play a key role in lithography processes for the fabrication of electronic devices, but must be removed after processing. The removal method using hydrogen radicals, which are produced on a tungsten hot-wire catalyst, is effective to resolve some environmental and industrial problems in usual methods. However, the removal rate is not as good as that of the usual methods. We have previously described that the removal rate is enhanced just by decreasing Hydrogen pressure but the rate limitations not clarified. In present study, we examined the removal rate dependence on the pressure and revealed that the upper limitation of the enhancement is achieved at 0.50 Pa. The removal rate at 0.50 Pa was 8.3 times higher than that at 20 Pa when the surface temperature was 250
oC.
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Yukinori Yamauchi, Naoki Doi, Yasushi Sasai, Shin-ichi Kondo, Masayu ...
2017 Volume 30 Issue 3 Pages
303-306
Published: June 26, 2017
Released on J-STAGE: August 10, 2017
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A methacrylic-type polymerizable derivative of naproxen (NP), planned as a prodrug, was directly synthesized from the reaction between 2-hydroxyethyl methacrylate (HEMA) and NP by the esterification method. Then, the polymeric prodrugs containing NP pendent groups were synthesized by the free radical polymerization on plasma irradiated pharmaceutical excipient powders. Hydrolysis of the polymeric prodrugs was carried out in conditions similar to physiological conditions and the results showed that the studied polymeric prodrugs in the present investigation can be used as carriers in controlled drug release, to meet the need for prolonged and better control of drug administration.
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Masaaki Nagatsu, Masahiro Kimpara, Rui Hu, Tomy Abuzairi
2017 Volume 30 Issue 3 Pages
307-312
Published: June 26, 2017
Released on J-STAGE: August 10, 2017
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Fluoropolymers are difficult materials to modify the surfaces because of strong C-F bonds. In this study, the surface modification of fluoropolymer films such as polytetrafluoroethylene (PTFE) with amino groups was performed by using He/NH
3 gas mixture atmospheric pressure plasma jets with negatively-biased substrate. It is expected that the ion bombardment effect onto the polymer surface due to negative substrate bias will make dangling bonds over the polymer surface and eventually promote the surface modification. From XPS analysis, we confirmed the breaking C-F bonds and creating C-C, C=O or C-N bonds in C 1s spectrum and increasing nitrogen-containing functional groups in N 1s spectrum. Fluorescence patterns were observed on the amino group functionalized PTFE surface by using the fluorescent dyes selectively connecting with the amino groups. With a spectrophotometric method, the surface concentration of amino groups introduced onto the PTFE surface was evaluated to be roughly 3.86 nmol/cm
2.
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Shin-ichi Kondo, Yasushi Sasai, Naoki Doi, Yukinori Yamauchi, Masayuk ...
2017 Volume 30 Issue 3 Pages
313-316
Published: June 26, 2017
Released on J-STAGE: August 10, 2017
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We describe the development of a novel palladium catalyst supported on a durable hydrophilic surface fabricated by the plasma-assisted method. Pd nano particles were immobilized on the polymer film possessing a durable hydrophilic surface (LDPE-Pd film). Two kinds of LDPE-Pd film possessing different Pd density were prepared to estimate the chemoselective hydrogenation. Stilbene and 4-nitroaniline were readily hydrogenated with LDPE-Pd film, indicating that the temperature and density of Pd on film might be very important for chemoselectivity.
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Jun-Seok Oh, Endre J. Szili, Sung-Ha Hong, Nishtha Gaur, Takayuki ...
2017 Volume 30 Issue 3 Pages
317-323
Published: June 26, 2017
Released on J-STAGE: August 10, 2017
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With ambient mass spectrometry, we followed the transport of neutral gas species and ionic species through a 3.2 mm thick agarose tissue model target during He non-thermal atmospheric pressure plasma (NT-APP) jet treatment. We found that the neutral gas species are unable to efficiently penetrate the agarose target. But both positively and negatively charged ionic species readily penetrate through the agarose target, following an initial time-lag period of several minutes. Interestingly, we also found that the ionic species are easily hydrated. The trends in the He NT-APP jet transport of ionic species observed in this study correlate well with the He NT-APP jet transport of reactive oxygen and nitrogen species (RONS) through agarose tissue model targets that was investigated in previous studies. Therefore, mass spectrometry might prove to be a useful tool in the future for analyzing the dosages of NT-APP-generated RONS in real biological tissues.
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Hai Dang Nguyen, Tatsuhiko Yajima
2017 Volume 30 Issue 3 Pages
325-330
Published: June 26, 2017
Released on J-STAGE: August 10, 2017
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In this study, optical emission spectroscopy was used to investigate the advantages of using NH
3 and water with Ar gas plasma. To compare the plasma characteristics of N
2, NH
3, and Ar plasma, Ar/H
2O vapor and Ar/NH
3-H
2O were investigated. The results show that RF-ICP is non-thermal plasma with
Te higher than
Tg, especially in air, N
2, and Ar/NH
3-H
2O plasma with
Te of about 32,500 K (ca. 2.5 eV),
Tν of about 7000 K (ca. 0.5 eV),
Tr of about 1000 K, and
Tg of about 320 K. In the Ar/NH
3-H
2O plasma, similar to the Ar/H
2O plasma, water dissociated readily to form OH and H I radicals, and the high H I concentration makes NH
3 suppressed the dissociation reaction and may proposed ionization reaction to form NH
3+ ion that minimum pressure change. In the PTFE surface treatment with Ar/NH
3-H
2O plasma, the suppression of NH
3 dissociation may be caused by the increased formation of NH
3+, which is the main factor in promoting defluorination. The high OH radical concentration may increase the number of polar groups grafted to the polymer surface, decreasing the WCA and making the PTFE surface super hydrophilic after treatment.
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Tatsuyuki Nakatani, Junya Fukumoto, Akira Wada, Shuzo Yamashita
2017 Volume 30 Issue 3 Pages
331-336
Published: June 26, 2017
Released on J-STAGE: August 10, 2017
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One of the major problems encountered when using bioabsorbable magnesium alloy stents is their loss of strength over time, which is due to their high elution rates. Although the use of a diamond-like carbon (DLC) coating to overcome this drawback, the excellent biocompatibility of which has been confirmed, is drawing attention, research on its application to magnesium alloy stents is still scarce. The present research aims to verify the corrosion characteristics of DLC-coated magnesium alloys to establish a DLC coating technique that will allow controlling the decomposition rate of bioabsorbable magnesium alloys. DLC films were formed using a 13.56 MHz radio-frequency (RF) plasma chemical vapor deposition (CVD) apparatus, and the corrosion characteristics were verified using electrochemical measurements. The results of the experiments reveal that a DLC coating decreases the corrosion current density in comparison to an untreated magnesium alloy and that the inhibition of localized corrosion is possible. Application of this DLC coating is expected to provide a stent that is capable of preventing fractures caused by localized corrosion and to enable the control of the decomposition rate.
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Yasushi Inoue, Haruka Koike, Takumi Aihara, Osamu Takai
2017 Volume 30 Issue 3 Pages
337-340
Published: June 26, 2017
Released on J-STAGE: August 10, 2017
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Particles of silica with organic functional groups (SiO:CH) were synthesized by plasma- enhanced chemical vapor deposition with a trimethylmethoxysilane reactant, and the influence of substrate materials on deposition behaviors of the particles were investigated. The deposited films consist both of a uniform SiO:CH layer deposited on the substrates and of the SiO:CH particles or their aggregates on the layer surfaces. The spherical shape of the particles indicates that they are polymerized through a homogeneous nucleation process in vapor phase. Averaged particle diameters are almost same on any type of the substrate materials. On the other hand, the area densities of the particles on gold-coated glass or silicon substrates are much higher than that on a glass plate. Averaged particle number of an aggregate is also higher on the gold-coated substrates. These behaviors of the SiO:CH particles can be explained by electrical properties of the substrate materials.
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Akira Watanabe, Jinguang Cai
2017 Volume 30 Issue 3 Pages
341-343
Published: June 26, 2017
Released on J-STAGE: August 10, 2017
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Maskless laser direct writing method is expected to realize the on demand manufacturing of various kinds of devices in printed electronics. On demand fabrication of a copper mi-cropattern via laser direct writing using a copper nanoparticle ink and a sensor application in combination with graphene oxide were studied. A device consisting of a copper interdigital electrode and graphene oxide coating layer was applied to a humidity sensor.
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Katsuaki Yamane, Akira Kawai
2017 Volume 30 Issue 3 Pages
345-350
Published: June 26, 2017
Released on J-STAGE: August 10, 2017
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A functional double cone tube (DCT) array with gas trapping and high durability is developed in the application of artificial skin. A stereo-lithography system is employed to fabricate DCT made of acrylic resin. In an aqueous solution, a certain amount of gas can be trapped in the tube due to capillary force balance. Under applying an external load, internal stress is effectively released at the interface between top and base cones. In the tactile sensing investigation, softness and tackiness senses as an artificial skin are felt.
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Deanna Soucie, William Earley, Kenji Hosoi, Arata Takahashi, Takash ...
2017 Volume 30 Issue 3 Pages
351-359
Published: June 26, 2017
Released on J-STAGE: August 10, 2017
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The synthesis and lithographic evaluation of 193-nm and EUV photoresists that utilize a higher-order reaction mechanism of deprotection is presented. Unique polymers utilize novel blocking groups that require two acid-catalyzed steps to be removed. When these steps occur with comparable reaction rates, the overall reaction should be higher order (≤ 1.85). The LWR of these resists is plotted against PEB time for a variety of compounds to acquire insight into the effectiveness of the proposed higher-order mechanisms. Evidence acquired during testing of these novel photoresist materials supports the conclusion that higher-order reaction kinetics leads to improved LWR
vs. control resists.
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Kazuki Yamada, Masatoshi Yamato, Kenichi Oyama, Hidetami Yaegashi, ...
2017 Volume 30 Issue 3 Pages
361-365
Published: June 26, 2017
Released on J-STAGE: August 10, 2017
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We report on the utility of self-aligned quadruple patterning (SAQP) using dual carbon layers as mandrels and silicon oxide films as spacers to improve pattern comprehensive pattern fidelity, such as line edge roughness (LER)/ line width roughness, local critical dimension uniformity, and pattern placement, compared to the design. While the use of carbon layers and silicon oxide films enables reduced LER, the required etching selectivity between the two carbon layers was difficult to obtain. We gained this selectivity by infiltrating silicon into one carbon layer. Thus, a SAQP scheme was developed and successfully demonstrated to produce a sub-20-nm half pitch pattern. The low LER value obtained after etching the first carbon layer was preserved throughout the process.
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Michihiro Shirakawa, Toru Fujimori, Naohiro Tango, Kazuhiro ...
2017 Volume 30 Issue 3 Pages
367-372
Published: June 26, 2017
Released on J-STAGE: August 10, 2017
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The main challenge in ArF lithography is to reduce cost of ownership (CoO) because increase in multi-patterning process is generally required to obtain a fine pattern. As a consequence, industry strongly requires ArF lithography process with a fast scan speed scanner and low defectivity material for CoO. The breakthrough technology to improve defectivity and resolution simultaneously was the polarity-change property of film surface from hydrophobic to hydrophilic after alkaline development process because a property after development process should be only associated with defectivity, not with fast scan speed. The materials with high polarity change function were explored to EUV process to achieve low defectivity with good lithography performances.
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Takafumi Endo, Rikimaru Sakamoto, Keisuke Hashimoto, Daigo Saito, ...
2017 Volume 30 Issue 3 Pages
373-378
Published: June 26, 2017
Released on J-STAGE: August 10, 2017
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In advanced lithography technology, high planarity SOC (Spin-on-Carbon) materials which can planarize topography substrates are required in order to obtain enough process margin. We developed photo curing SOC (P-SOC) materials which can be cross-linked by short wavelength UV light, but not thermal process. The P-SOC can achieve high planarization and good via filling because they have high reflow performance without viscosity increasing by baking process and almost no film shrinkage during the baking and photo curing process. The novel P-SOC materials are suitable for very fine pattern manufacturing process as N5 generation which is needed planarization technology.
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