Journal of Photopolymer Science and Technology
Online ISSN : 1349-6336
Print ISSN : 0914-9244
ISSN-L : 0914-9244
Volume 29 , Issue 4
Showing 1-24 articles out of 24 articles from the selected issue
  • Hiroaki Takehara, Akira Nagaoka, Jun Noguchi, Takanori Akagi, Haruo K ...
    2016 Volume 29 Issue 4 Pages 513-518
    Published: June 21, 2016
    Released: September 01, 2016
    JOURNALS FREE ACCESS
    Imaging of neural cells in living mice is a promising approach in neuroscience research and neurological medicine. In this paper, we report an implantable micro-fluidic device with hydrogel permeable membrane, which acts as an interface with functions of delivering chemical compounds into brain tissues and imaging neural cells with high-resolution using two-photon laser scanning microscopy (2PLSM). Small pore size of the hydrogel permeable membrane enables filtration to avoid bacterial infection. For showing feasibility of the developed device in advanced neuroscience research, delivery of chemical compounds into the brain tissue and intravital imaging of neurons by 2PLSM were performed.
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  • Chie Kojima, Daichi Fukushima
    2016 Volume 29 Issue 4 Pages 519-523
    Published: June 21, 2016
    Released: September 01, 2016
    JOURNALS FREE ACCESS
    Gold nanoparticles (AuNPs) have photo-induced heat-generating properties, which can be applied to photothermal therapy. Dendrimers are synthetic macromolecules with a unique structure, and work as nanotemplates in the preparation of AuNPs, as well as potent vehicles. Previously, PEGylated dendrimer (PEG-den) has been used as a vehicle of AuNP. Thermosensitive elastin-mimetic dendrimers were previously prepared as a biocompatible thermosensitive nanoparticle by conjugating elastin-like peptides (ELPs) with valine-proline-glycine-valine-glycine (VPGVG) repeats to dendrimers. In this study, elastin-mimetic dendrimer (ELP-den) was used as a thermosensitive vehicle of AuNP. The AuNP-loaded ELP-den exhibited both photothermal and thermosensitive properties. AuNP-loaded ELP-den readily associated with cells and induced efficient photocytotoxicity, but the AuNP-loaded PEG-den did not. This suggests that ELP-den is a potent carrier of AuNPs for photothermal therapy.
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  • Masao Kamimura, Rie Saito, Hiroshi Hyodo, Kosuke Tsuji, Izumi O. Umeda ...
    2016 Volume 29 Issue 4 Pages 525-532
    Published: June 21, 2016
    Released: September 01, 2016
    JOURNALS FREE ACCESS
    In this study, we aimed to develop a dual-modal in vivo imaging based on over-1000 nm near-infrared (OTN-NIR) fluorescence and single photon emission computed tomography (SPECT)/computed tomography (CT). As an OTN-NIR nanophosphor material, Ytterbium and erbium ion co-doped yttrium phosphate nanoparticles (YPO4 NPs) was synthesized by a hydrothermal synthesis method. Biocompatible poly(ethylene glycol) (PEG)/polycation block copolymer and radioactive 111In were introduced on the YPO4 NPs surface (PEG-111In-YPO4 NPs). The PEG-111In-YPO4 NPs showed high dispersion stability in physiological saline and excellent radioactivity in any of PBS and FBS solutions. Furthermore, in vivo OTN-NIR fluorescence and SPECT /CT imaging of live mice was performed. Strong OTN-NIR emission from the blood vessel and organs of live mice were observed. Moreover, SPECT/CT images clearly showed the three dimensional images of the live mice. Therefore, PEG-111In-YPO4 NPs is an attractive candidate for the OTN-NIR fluorescence and SPECT/CT dual-modal imaging probe, and the concept can be served as a novel platform for real-time imaging and three dimensional quantitative determinations.
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  • Kyohei Nakano, Yujiao Chen, Kaori Suzuki, Keisuke Tajima
    2016 Volume 29 Issue 4 Pages 533-536
    Published: June 21, 2016
    Released: September 01, 2016
    JOURNALS FREE ACCESS
    We overview our recent progress in interfacial modifications, and discuss an ideal interfacial structure to realize highly efficient OSCs. Energetic structures of donor and acceptor materials near their interface affect device performance; however, only tuning their energy level may not be enough to achieve efficient solar cells. A key factor that should be considered is an additional interlayer between the donor and the acceptor, which has been proposed to form naturally in mixed bulk-heterojunction type solar cells.
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  • Hiroaki Benten, Takaya Nishida, Daisuke Mori, Hideo Ohkita, Shinzaburo ...
    2016 Volume 29 Issue 4 Pages 537-540
    Published: June 21, 2016
    Released: September 01, 2016
    JOURNALS FREE ACCESS
    Ternary blend all-polymer solar cells are developed to broaden the absorption bandwidth of the photoactive layer. A wide-bandgap polymer with absorption in the visible region is introduced as a third polymer into a low-bandgap donor/acceptor binary polymer blend showing absorption in the near-infrared (NIR) region. In the ternary blend solar cell, the external quantum efficiency (EQE) is improved in the visible wavelength region, while retaining the excellent EQE of the host binary blend in the NIR wavelength region. These results demonstrate that the use of ternary blends of conjugated polymers containing a wide-bandgap polymer as a visible sensitizer is an effective approach for improving the efficiency of all-polymer solar cells.
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  • Kazuhiro Marumoto, Dong Liu, Masaki Yabusaki
    2016 Volume 29 Issue 4 Pages 541-545
    Published: June 21, 2016
    Released: September 01, 2016
    JOURNALS FREE ACCESS
    The degradation mechanism of polymer solar cells containing a lithium-fluoride (LiF) buffer layer created by a thermal annealing process at different temperatures was studied using an electron spin resonance (ESR) and current-voltage characteristics. The device structure was indium-tin-oxide (ITO)/poly(3,4-ethylenedioxythiophene): poly(4-styrenesulfonate) (PEDOT:PSS)/poly(3-hexylthiophene):phenyl-C61-butyric acid methyl ester (P3HT:PCBM)/LiF/Al. When the post-annealing temperature increased, the performance of the cells decreased and the ESR signal from PCBM radical anions was enhanced dramatically. The formation of a greater number of anions enhanced the electron scattering and caused an energy-level shift at the interface. These effects led to degradation in the device performance.
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  • Shunjiro Fujii, Kosei Hashiba, Tetsuo Shimizu, Yasushiro Nishioka, Hir ...
    2016 Volume 29 Issue 4 Pages 547-551
    Published: June 21, 2016
    Released: September 01, 2016
    JOURNALS FREE ACCESS
    Semitransparent inverted bulk-heterojunction solar cells were fabricated on an ITO/glass substrate utilizing oxide/metal/oxide transparent anode. The device structure was glass/ITO/PFN/PTB7:PC71BM/MoO3/Au/MoO3. The semitransparent solar cell showed a transparency of 44% at 550 nm and bifacial power generation at both front and backside illumination. The power conversion efficiencies (PCEs) with light illuminated from ITO or Au/MoO3 side were 2.8% and 2.3%, respectively. Fabrication of stacking structure of two separated solar cells was further demonstrated to harvest an increased amount of photons and enhance the PCEs. The stacked cells showed a transmittance of 17% at 550 nm and improved PCE of 3.3% when connecting two cells in parallel.
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  • Yuxiang Li, Tack Ho Lee, Jihyeon Kim, Song Yi Park, Seyeong Song, Sung ...
    2016 Volume 29 Issue 4 Pages 553-559
    Published: June 21, 2016
    Released: September 01, 2016
    JOURNALS FREE ACCESS
    Supplementary material
    Two planar type photovoltaic polymers based on naphthobisthiadiazole, poly(2,5-bis(2-hexyldecyloxy)phenylene-alt-(5,10-dithiophen-2-yl)naphtho[1,2-c:5,6-c]bis[1,2,5]thiadiazole) (h-PPDTNTz) and poly(2,5-bis(2-decyltetradecyloxy)phenylene-alt-(5,10-dithiophen-2-yl)naphtho[1,2-c:5,6-c]bis[1,2,5]thiadiazole) (d-PPDTNTz) were synthesized by incorporating intrachain noncovalent Coulombic interactions in the molecular design. To achieve a delicate balance of molecular weight, solubility as well as bulk film morphology, hexyldecyloxy (h-) and decyltetradecyloxy (d-) side-chains were substituted, which played a decisive role in modulating morphology, film packing structure and macroscopic device properties. Both polymers showed a broad light absorption up to ~800 nm and d-PPDTNTz exhibited a deeper HOMO and preferentially face-on orientation in pristine and blended films with PC71BM. The detailed optical, electrochemical, thermal, morphological and the resulting photovoltaic characteristics were studied. The best power conversion efficiency of ~6.7% was measured for d-PPDTNTz:PC71BM, suggesting that the careful choice of side-chains is necessary for fully optimize the photovoltaic materials and devices.
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  • Taku Miura, Takashi Tachikawa, Yasuhiro Kobori
    2016 Volume 29 Issue 4 Pages 561-564
    Published: June 21, 2016
    Released: September 01, 2016
    JOURNALS FREE ACCESS
    We have investigated the morphology effect on the nanostructure and the exchange coupling of the interfacial CS states in the RR-P3HT:PC60BM film. In the lower RR-P3HT content, the polymer crystalline phase is not formed by the strong interactions from the PC60BM molecules, resulting in the short-range CS states with the quick energy-wasting recombination. For the higher polymer content, it has been demonstrated that the PC60BM molecules bind to the crystalline polymer regions at the BHJs and that the hole-dissociations take place accompanying the delocalized hole distribution, resulting in the long-lived photocarrier generations. The above structural and electronic properties are essential keys to evaluations, designs, and developments of the highly efficient solar energy-conversion systems employing organic polymers in the OPV systems.
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  • Marina Ide, Yoshiko Koizumi, Akinori Saeki
    2016 Volume 29 Issue 4 Pages 565-569
    Published: June 21, 2016
    Released: September 01, 2016
    JOURNALS FREE ACCESS
    A new low-bandgap polymer composed of benzothienoisoindigo (BTIDG) and benzodithiophene (BDT) was designed and synthesized. By virtue of unsymmetrical BTIDG moiety, BDT-BTIDG copolymer exhibits moderate electrochemical properties in both bandgap (1.5 eV) and the highest occupied molecular orbital (HOMO, -5.4 eV). They are 0.4 eV wider and 0.5 eV deeper than those of previous symmetric thienoisoindigo (TIDG)-BDT analogue, respectively. Although the BDT-BTIDG is highly soluble in common organic solvents like chlorobenzene, the blend film of phenyl-C61-butyric-acid-methyl ester (PCBM) caused a large phase separation over 200 nm spatial scale, leading to a structural color due to light interference. We have mitigated the phase separation to some extent using chloroform and solvent additive, giving the PCE of 0.83% for BDT-BTIDG:PCBM = 1 : 2. This work indicates that solubility of copolymer is not directly relevant to optimal bulk heterojunction morphology.
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  • Yutaka Ie, Shohei Sasada, Makoto Karakawa, Yoshio Aso
    2016 Volume 29 Issue 4 Pages 571-574
    Published: June 21, 2016
    Released: September 01, 2016
    JOURNALS FREE ACCESS
    We developed PBTz-containing new D-A copolymer P-PBTz-T12-BDT. EHOMO and ELUMO were determined by the combination of PESA and UV-vis measurements in the solid state. SCLC measurements showed the hole-transporting characteristics. BHJ solar cells based on P-PBTz-T12-BDT and PC61BM showed a moderate PCE of 1.08%. To further improve the PCE, the fine-tuning of the film morphology by the alkyl side-chain engineering and/or the structural modification of π-conjugated backbones have become important, which will lead to increasing the crystallinity in the solid state. Nevertheless, the obtained results confirm that PBTz has been positioned as a good candidate for the acceptor unit for the development of high-performance organic semiconducting materials.
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  • Tomohiro Fukuhara, Miki Osaka, Yasunari Tamai, Hideo Ohkita, Hiroaki ...
    2016 Volume 29 Issue 4 Pages 575-580
    Published: June 21, 2016
    Released: September 01, 2016
    JOURNALS FREE ACCESS
    Polymer solar cells with a thick active layer can generate large photocurrent because they absorb many more photons. In most cases, however, the active layer is as thin as ~100 nm under the optimized condition. In this work, we have studied bimolecular charge recombination in highly efficient polymer solar cells with a thick active layer by transient photovoltage and photocurrent measurements. As a result, we found that the bimolecular recombination rate is smaller by three orders of magnitude than that predicted from the diffusion-limited Langevin recombination. We therefore conclude that such reduced bimolecular recombination enables efficient charge collection even in the solar cell with a thick active layer.
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  • Vincent Obiozo Eze, Tatsuo Mori
    2016 Volume 29 Issue 4 Pages 581-586
    Published: June 21, 2016
    Released: September 01, 2016
    JOURNALS FREE ACCESS
    We report on methylammonium lead halide perovskite solar cells using α-naphthyl diamine derivative of N,N'-bis (1-naphthyl)-N,N'-diphenyl-1,1'-diphenyl-1,4'-diamine (α-NPD) as a hole transport material (HTM) with a light to electricity power conversion efficiency (PCE) of 6.03%, short-circuit current density of 15.60 mA/cm2, the open-circuit voltage of 0.84 V, and fill factor of 0.46 under AM 1.5G illumination of 100 mW/cm2 intensity. The performance of the α-NPD-based device was compared with the device incorporating 2,2',7,7'-tetrakis-(N,N'-di-p-methoxyphenylamine) 9,9'-spirobifluorene (spiro-OMeTAD), which is the most widely used HTM for perovskite solar cells. This work shows that α-NPD can be employed as a low-cost hole transport layer (HTL) for perovskite solar cells.
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  • Toshiyuki Horiuchi, Shota Haneishi, Yumika Yoshida, Hiroshi Kobayashi
    2016 Volume 29 Issue 4 Pages 587-593
    Published: June 21, 2016
    Released: September 01, 2016
    JOURNALS FREE ACCESS
    Width homogenization of patterns printed by the desktop matrix-exposure system using a commercial liquid-crystal-display projector was investigated. At first, it was thought that the pattern width distribution caused by the dispersion of illumination-light intensity would be easily compensated by adjusting each bright cell transmittance. However, it was fundamentally difficult. Bottom peaks of the image intensity did not reach zero caused by the diffraction and intrinsic transmittance of black cells. For this reason, the bottom peaks also distributed depending on the illumination-light intensity. As a result, image contrast was degraded by reducing the transmittance of bright cells. To print line-and-space (L&S) patterns homogeneously in the exposure field, it was also necessary to increase the transmittance of black cells at places where the illumination-light intensity was low. By this countermeasure, down to 2-pixel L&S patterns were printed almost homogeneously. The width distribution of 4- and 5-pixel L&S patterns was suppressed almost within ±10%.
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  • Toshiyuki Horiuchi, Ryunosuke Sasaki
    2016 Volume 29 Issue 4 Pages 595-601
    Published: June 21, 2016
    Released: September 01, 2016
    JOURNALS FREE ACCESS
    Almost spherical concave resist patterns in a dense array were fabricated to be used as reversal molds of plastic convex micro-lens arrays. In the past research, such micro-lens arrays were replicated using concave metal molds fabricated by replicating original convex resist patterns. However, it was difficult to fabricate the original convex resist patterns densely in a matrix. In addition, because two replication processes from resist to metal and from metal to plastic resin were necessary, procedures were very complicated, and it took long times for obtaining final plastic resin lens arrays. In the new method, original concave mold patterns were obtained by simple 1/19 projection-exposure lithography including only one exposure and one development by applying largely defocused exposure intentionally. Despite the simplicity, very wide-range curvature radiuses of 25-120 µm were obtained by giving various exposure doses even using reticles with same 500-µm transparent square patterns. It was basically checked that epoxy resin lens arrays were obtained by mechanically separating them from the concave resist molds.
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  • Hiroki Nakano, Kenta Takahashi, Akira Kawai
    2016 Volume 29 Issue 4 Pages 603-606
    Published: June 21, 2016
    Released: September 01, 2016
    JOURNALS FREE ACCESS
    By the combination of EB (electron beam) pattern irradiation and UV (ultraviolet) exposure processes, negative tone pattern can be formed in a positive type resist film. It is well known that a novolac resin based resist film can be crosslinked by thermal and EB irradiation processes. By changing the EB irradiation and UV light exposure doses, a dissolution resistance of the resist film to TMAH (tetramethylammoniumhydroxide) alkaline aqueous solution can be controlled. As the result, the EB/UV hybrid lithography is effective for the fabrication of difference height patterns in a single resist layer. A dose response characteristic of a resist film is determined. A roughness of resist pattern in EB/UV hybrid lithography is also discussed. As an application, a micro square vessel array is fabricated used for a bioelectronic field.
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  • Masahiro Furutani, Ayaru Kakinuma, Koji Arimitsu
    2016 Volume 29 Issue 4 Pages 607-608
    Published: June 21, 2016
    Released: September 01, 2016
    JOURNALS FREE ACCESS
    We have designed a carbamate of an aliphatic diamine having a disulfide bond, and proposed an anionic UV curing system consisting of a photobase generator,the carbamate and a bifunctional epoxy resin. We examined whether the carbamate works as a base amplifier (BA) that generates a base molecule autocatalytically with a trigger base in a base proliferation reaction.
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  • Atsushi Shiraishi, Yasuhiro Ueda, Michael Schlapfer, Christian Schmitz ...
    2016 Volume 29 Issue 4 Pages 609-615
    Published: June 21, 2016
    Released: September 01, 2016
    JOURNALS FREE ACCESS
    Photoinitiated Polymerization of TPGDA was initiated with a NIR LED emitting at 790 nm using a redox based photoinitiator system comprising a cyanine as photosensitizer and a diaryl iodonium salt. The latter bears different anions exhibiting low coordination behavior; that is [B(Ph)4]-, [B(PhF5)4]-, [B(Ph(CF3)2)4]-, [B(Ph-4-Cl)4]-, [(CF3SO2)2N]-, PF6-, and [PF3(C2F5)3]-. Photo-DSC was applied to determine photopolymerization activity. This correlated with the conductivity with many of these anions showing that reactivity mostly correlates with ion mobility. Nevertheless, iodonium salts bearing as anions either [PF3(C2F5)3]-, [B(Ph(CF3)2)4]- or [(CF3SO2)2N]- exhibit an excellent solubility being larger than several 100 g L-1. Furthermore, NIR sensitized cationic photopolymerization of aziridines was successfully demonstrated.
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  • Daiki Kashiwai, Yuiichi Kaneko, Takuma Sawada, Yusuke Sato, Shigeru Ta ...
    2016 Volume 29 Issue 4 Pages 617-622
    Published: June 21, 2016
    Released: September 01, 2016
    JOURNALS FREE ACCESS
    We developed novel photo amphoteric compound generators (PAmGs) as a kind of photo-X- generators (PXGs), such as photo-acid generator (PAG). Onium salts that were prepared here generate sulfanilic acid, taurine, or 1-aminoadamantane-3-sulfonic acid in the photochemical reactions. These PAmGs are water-soluble, and photo-decomposable basic compounds to control pH of aqueous solution from basic to acidic side depending on the photon energy absorbed. The PAmG having aminoadamantane structures acted as a better acid-quencher than others did in polymer film. It has the possibility to enhance the contrast of acid concentration related with the resolution of photoresist using PAG. Furthermore, these water-soluble PAmGs induced the photo gelation of alginate by the pH control.
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  • Kohei Matsuura, Takashi Nishiyama, Eriko Sato, Masashi Yamamoto, Tomos ...
    2016 Volume 29 Issue 4 Pages 623-627
    Published: June 21, 2016
    Released: September 01, 2016
    JOURNALS FREE ACCESS
    We studied about an effect of temperature on degradation of polymers for photoresist using ozone microbubbles as an environmentally friendly cleaning technique. The dissolved ozone concentration of ozone microbubbles was decreased with the increasing temperature because the solubility of ozone gas was decreased and self-decomposition of ozone in water was promoted. While, the reactivity between ozone and novolak resin was increased with the increasing temperature. Consequently, novolak resin was most efficiently removed at around 23 oC. The activated energy for removal of novolak resin using ozone microbubbles was 23 kJ/mol determined from Arrhenius plots. Polyvinyl phenol was removed by ozone microbubbles, and its removal rate was comparable with that of novolak resin. Polymethyl methacrylate without C=C bond or benzene ring structure could not be removed by ozone microbubbles.
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  • Seiji Takagi, Takashi Nishiyama, Masashi Yamamoto, Eriko Sato, Tomosum ...
    2016 Volume 29 Issue 4 Pages 629-631
    Published: June 21, 2016
    Released: September 01, 2016
    JOURNALS FREE ACCESS
    We investigated the formation of microstructure on the surface of Poly(methyl methacrylate) - based polymer (PMMA - based polymer), which is a polymer for the ArF photoresist, in decomposition process by using atomic hydrogen generated by a tungsten hot-wire catalyst.
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  • Tomosumi Kamimura, Kosuke Nuno, Yuta Kuroki, Takayuki Yamashiro, Sing ...
    2016 Volume 29 Issue 4 Pages 633-637
    Published: June 21, 2016
    Released: September 01, 2016
    JOURNALS FREE ACCESS
    Removal by using laser irradiation was investigated in Poly-Vinyl Phenol (PVP). The laser irradiation in the water can improve the PVP stripping effect as compared with that of normal atmosphere irradiation. The surface laser damage threshold of Si wafer was 0.13 J/cm2, and the PVP stripping threshold was 0.06 J/cm2. The PVP stripping threshold decreased to approximately 50 % of the surface laser damage threshold. The PVP strips from the Si wafer just as shown in a positive-tone DNQ / novolak resist. However, removal efficiency decreased at a large irradiation beam diameter. The stripped area decreases at the beam diameter of 1.5mm or more. Irradiation with multiple laser beams with a small beam diameter could improve the PVP stripping rate with high efficiency.
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  • Masashi Yamamoto, Kazuma Maejima, Hironobu Umemoto, Keisuke Ohdaira, T ...
    2016 Volume 29 Issue 4 Pages 639-642
    Published: June 21, 2016
    Released: September 01, 2016
    JOURNALS FREE ACCESS
    We examined an environmentally friendly photoresist removal method using radicals produced by decomposing a mixture of hydrogen and oxygen on hot tungsten catalysts. Results show that the photoresist removal uniformity is enhanced remarkably with the optimal amount of oxygen addition. By further optimizing conditions, the removal uniformity and the inclusive removal rate might become comparable to those achieved when chemicals are used.
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  • Masayoshi Takahashi, Yasuyuki Shirai, Akinobu Teramoto, Tunejirou Taka ...
    2016 Volume 29 Issue 4 Pages 643-646
    Published: June 21, 2016
    Released: September 01, 2016
    JOURNALS FREE ACCESS
    We need to enhance the removing ability of microbubbles through the clear understanding of the functional mechanisms of microbubbles for the removal of photoresist layers. The purpose of the present study is to clarify the effect of microbubble on the surface of photoresist layers.
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