Journal of Photopolymer Science and Technology
Online ISSN : 1349-6336
Print ISSN : 0914-9244
ISSN-L : 0914-9244
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Displaying 1-20 of 20 articles from this issue
  • Marina Doi, Koichiro Muto, Mayuko Nara, Naiqiang Liang, Kosuke Sano, H ...
    2021 Volume 34 Issue 5 Pages 423-430
    Published: June 11, 2021
    Released on J-STAGE: November 23, 2021
    JOURNAL FREE ACCESS

    The photoluminescence (PL) properties of semi-aromatic polyimide (PI) films and their model compounds (MCs) prepared from dianhydrides having a rigid naphthalene core were analyzed. The PMMA-dispersed MC and copolymerized PI (CoPI) films derived from 2,3,6,7-naphthalenetetracarboxylic dianhydride (NTDA) exhibited long-lived phosphorescence owing to the suppression of molecular motion by the rigidity of a naphthalene core. Additionally, the PMMA-dispersed MC and the CoPI films derived from 1,5-dibromo derivative of NTDA (DBrNT) exhibited room-temperature phosphorescence due to the enhancement of spin-orbit coupling by bromine atoms. The photophysical processes of the CoPI films prepared from NTDA/DBrNT and 4,4'-oxydiphtalic dianhydride (ODPA) in which the latter absorption band is located at a shorter wavelength than the former were analyzed. After UV irradiation, efficient excitation energy transfer occurs from the ODPA to NTDA/DBrNT moieties, and only the emission from the latter moieties was observed. These results demonstrate that the CoPI films derived from two dianhydrides absorbing different UV wavelengths can be used as spectral conversion films that convert a wide range of UV-light into longer wavelength visible light.

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  • Takahiro Komamura, Yuta Nabae, Teruaki Hayakawa
    2021 Volume 34 Issue 5 Pages 431-437
    Published: June 11, 2021
    Released on J-STAGE: November 23, 2021
    JOURNAL FREE ACCESS

    Crosslinked porous polyimide films were fabricated by a soft-template method using the microphase-separated structure based on a template block copolymer. A trifunctional amine, 1,3,5-tris(4-aminophenyl)benzene (TAPB), was used as a crosslinkable monomer of the poly(amic acid) (PAA) to achieve the well-ordered and flexible films. The crosslinking by TAPB improved the thermal stability of the nanostructures of the PAA/polystyrene-b-poly(2-vinyl pyridine) composite films without reduction of the ratio of polyimide. A porous polyimide film was successfully fabricated by thermal treatment of a PAA composite film that has porous lamella structures and disordered porous structures with approximately 50 nm gaps based on the nanostructure of the PAA composite films before thermal treatment.

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  • Hayato Maeda, Yuta Nabae, Teruaki Hayakawa
    2021 Volume 34 Issue 5 Pages 439-448
    Published: June 11, 2021
    Released on J-STAGE: November 23, 2021
    JOURNAL FREE ACCESS

    This study aimed to form a perpendicularly orientated lamellar structure with polystyrene-block-poly(methyl methacrylate) (PS-b-PMMA) by its microphase separation on a polyimide substrate. Eight types of polyimides were prepared from different combinations of monomers and tested as the bottom layer for the microphase separation of PS-b-PMMA. The surface free energies of those polyimide substrates were evaluated by the Owens-Wendt method. Thin films of PS-b-PMMA were prepared on the polyimide substrates and the self-assembly was induced by thermal annealing, and the surface architecture was observed by atomic force microscopy. In the tested polyimide substrates, only one from 2,2-bis[4-(3,4-dicarboxyphenoxy) phenyl]propane dianhydride (tetracarboxylic dianhydride) and 1,12-bis (4-aminophenoxy) dodecane (diamine) showed a perpendicularly oriented lamellar structure. This polyimide substrate shows one of the smallest polar components in its surface free energy. Relatively large domain size and long correlation length in the PS-b-PMMA layer were obtained by optimizing the conditions for fabrication of the polyimide substrate, which were prepared by casting the polyimide onto a silicon wafer, followed by thermal annealing. These results suggest that the combination of one monomer with relatively large molecular weight, which will result in a low density of imide groups, and the other monomer with long alkyl chains, which will reduce the polarity of the resulting polyimide, contributes to providing a perpendicular orientation.

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  • Shiori Higashi, Masafumi Yamato, Hiroyoshi Kawakami
    2021 Volume 34 Issue 5 Pages 449-456
    Published: June 11, 2021
    Released on J-STAGE: November 23, 2021
    JOURNAL FREE ACCESS

    The asymmetric mixed matrix membrane (MMM) composed of fluorinated polyimide and the surface-modified silica nanoparticles were fabricated using the dry-wet phase inversion method. The thinning of the skin layer of the asymmetric MMM led to a significant improvement in gas permeability and a decrease in gas selectivity. The decrease in gas selectivity originated in particle coarsening before vitrification caused by immersion in the coagulation bath. In addition, particle aggregation, that was caused by liquid-liquid phase separation due to evaporation of good solvent, occurred even before immersion in the coagulation bath. The composition of the mixed solvent, which allow suppression of particle aggregation during both dry and wet processes, is important to produce defect-less asymmetric MMMs.

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  • Yoshikatsu Shiina, Shohta Ohnuki, Atsushi Morikawa
    2021 Volume 34 Issue 5 Pages 457-462
    Published: June 11, 2021
    Released on J-STAGE: November 23, 2021
    JOURNAL FREE ACCESS

    Deformation of a polyamic acid gel was observed upon heating. The gel prepared from 1,1-bis[4-(aminophenoxy) phenyl]-1-[4-(4-amino-2-trifluoromethylphenoxy) phenyl] ethane (triamine-CF3), 4,4’-oxydianiline (ODA) and benzohenonetetracarboxylic dianhydride (BTDA) in N-methyl-2-pyrrolidone (NMP) at 20 °C was heated to 180 °C. The swelling became weak upon increasing the temperature, and the gel turned into a solution that could be stirred easily above 80 °C. The solution heated to 180 °C did not returned to the gel state even upon cooling to 20 °C. IR measurements of the heated gel showed that the deformation was due to an amide exchange reaction, which proceeded through scission of the amide linkage into anhydride and amine end groups. The viscosity barely changed upon heating. The amide exchange and imidation reactions proceeded simultaneously upon heating the polyamic acid gel, and formed a soluble polyimide containing amino sidechains.

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  • Takahiro Ogura, Kazuto Suzuki, Manabu Tanaka, Hiroyoshi Kawakami
    2021 Volume 34 Issue 5 Pages 463-468
    Published: June 11, 2021
    Released on J-STAGE: November 23, 2021
    JOURNAL FREE ACCESS

    Nanofiber Framework (NfF)-based polymer electrolyte membranes were investigated for polymer electrolyte fuel cells. New processes, including the hot-pressing and vapor-welding, were attempted to the polybenzimidazole nanofibers (PBINfs) to increase the fractions and connectivity of the Nfs. The phytic acid (Phy)-doping to the Nfs and the followed composition with Nafion gave hot-pressed NfF (HPNfF)/Nafion and vapor-welded NfF (VWNfF)/Nafion composite membranes. These new composite membranes showed higher proton conductivity than a conventional NfF composite membrane by forming connected effective proton conductive pathways at the interface of the three-dimensionally connected Nfs and the matrix polymer electrolyte. The mechanical and gas barrier properties were also evaluated to reveal the effectiveness of the new processes.

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  • Takuya Kitano, Takeshi Aizawa, Tatsuo Ishijima, Hiroaki Suzuki, Arufua ...
    2021 Volume 34 Issue 5 Pages 469-478
    Published: June 11, 2021
    Released on J-STAGE: November 23, 2021
    JOURNAL FREE ACCESS

    Mechanisms of photoresist removal were investigated using microwave-excited plasma in saturated water vapor under a reduced pressure condition (approx. 6 kPa). A few seconds of white emission were observed at the beginning of photoresist removal. To ascertain the species of spectra, optical emission spectroscopy was used for photoresist removal from a Si wafer. Emission spectra of OH (A2Σ – X2Π), Hα (656 nm), and O (777 nm) derived from dissociation of water molecules were observed. Other emission spectra attributed to CO molecules were also detected and identified as the Ångström system (B1Σ – A1Π). This result indicates CO molecule generation during photoresist removal. The CO molecule emission intensity reached a maximum value at 1.1 s after plasma ignition, whereas those of OH, Hα, and O reached a minimum value at almost identical time. Furthermore, normalized emission spectra shape from CO molecules during photoresist removal were almost identical for Δv = +1, 0, -1, -2, -3, and -4. Rotational and vibrational temperatures of the CO molecules during photoresist removal were found to be almost constant and to be 1500 and 2500 K, respectively. These results suggest increased CO molecular density above the Si wafer at 1.1 s.

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  • Takeshi Aizawa, Taishin Shimada, Tasuku Sakurai, Yusuke Nakano, Yasuno ...
    2021 Volume 34 Issue 5 Pages 479-484
    Published: June 11, 2021
    Released on J-STAGE: November 23, 2021
    JOURNAL FREE ACCESS

    In this study, the uniformity of a photoresist ashing for a half-inch wafer was improved by a developed antenna structure, a double U-shaped antenna, in microwave-excited water vapor plasma. The optimized double U-shaped antenna structure, obtained by simulating an electric field, generated a spread distribution microwave plasma. Experimentally obtained results demonstrate that the observed optical emission distribution image from the microwave plasma resembles the electric field distribution obtained from the simulation under the present water vapor plasma generation condition. The double U-shaped antenna showed a higher ashing rate and better uniformity than the conventional slot antenna.

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  • Kazuki Tsujimoto, Hideo Horibe
    2021 Volume 34 Issue 5 Pages 485-489
    Published: June 11, 2021
    Released on J-STAGE: November 23, 2021
    JOURNAL FREE ACCESS

    Microbubbles are tiny bubbles with a particle size of 1 - 100 μm. Microbubbles have been reported that the gas dissolving ability is excellent and hydroxyl radical generates when microbubbles collapse in water. On the other hand, ozone is a gas with high oxidation power and eventually decomposes into oxygen. So, ozone is environmentally friendly. Therefore, we thought that ozone microbubbles water, in which ozone is dissolved in microbubbles water, could be used to efficiently decompose persistent organic compounds while being environmentally friendly. In this study, we evaluated the decomposition of phenol, an object subject to wastewater regulation, by ozone water and ozone microbubbles water. At a constant dissolved ozone concentration, we could not confirm the effect of microbubbles in decomposing phenol. Also, under the same conditions, when the pH was changed, the effect of microbubbles could not be confirmed. However, under basic conditions, phenol was decomposed the most because of self-decomposition reaction of ozone. Therefore, the effect of microbubbles could not be confirmed in the phenol degradation by ozone microbubbles in this experiment.

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  • Shinya Akechi, Hideo Horibe
    2021 Volume 34 Issue 5 Pages 491-494
    Published: June 11, 2021
    Released on J-STAGE: November 23, 2021
    JOURNAL FREE ACCESS

    A photosensitive polymer called photoresist is used to create fine circuit patterns on the surface of semiconductors. The aim of this study was to improve the resist function by incorporating a chemical amplification mechanism into the base polymer, novolac resin. The resist is composed of three components: base polymer, dissolution inhibitor (DI), and photoacid generator. The ability to inhibit the dissolution of resist polymer in the unexposed area was improved by increasing the molecular size of DI. The high acidity of deprotected DI with carboxyl groups improved the ability to promote dissolution of resist polymer in the exposed area. The resists containing DIs with large molecular size and high acidity showed improved resolution.

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  • Shunpei Kajita, Yukiko Miyaji, Hideo Horibe
    2021 Volume 34 Issue 5 Pages 495-498
    Published: June 11, 2021
    Released on J-STAGE: November 23, 2021
    JOURNAL FREE ACCESS

    Photoresist is used for circuit fabrication in semiconductor devices. The material generally used for manufacturing semiconductor devices is the novolak-type positive-tone resist; however, it is necessary to minimize its line width while improving the resolution. To improve the resolution of novolak-type positive-tone resist, in this study, developers containing water-soluble organic solvents or surface-activating agents have been designed for controlling the resist solubility. The addition of glycerol, as a water-soluble organic solvent in the developer, inhibits the dissolution of the novolak resist, particularly in the unexposed area. The developer containing glycerol improves the novolak resist resolution, thereby developing a fine pattern.

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  • Koki Akita, Shota Sogo, Ryusei Sogame, Masashi Yamamoto, Shiro Nagaoka ...
    2021 Volume 34 Issue 5 Pages 499-504
    Published: June 11, 2021
    Released on J-STAGE: November 23, 2021
    JOURNAL FREE ACCESS

    We earlier reported that addition of a small amount of O2 gas in the atmosphere where H radicals are generated on a high-temperature tungsten filament improves the photoresist removal rate of positive-tone novolac photoresists for i/g lines. This study investigated effects of photo-active compound (PAC) on the photoresist removal. Addition of more than 1.5 sccm of oxygen to 100 sccm of hydrogen gas flow decreased the removal rate. In pure novolac resin, cross-linking of the resin can be one of the causes of this decrease at temperatures higher than 240 °C. The rate of removal with PAC decreased much more than with pure novolac resin over 240 °C. This removal rate decrease might be ascribed to cross-linking not only between the resin and the PAC but also between the resins. OH radicals can be used effectively for photoresist removal by generating sufficient H radicals to prevent such cross-linking.

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  • Atsuki Hosaka, Tsubasa Miyaki, Yuki Mizushima, Satomi Hamada, Ryota Ko ...
    2021 Volume 34 Issue 5 Pages 505-509
    Published: June 11, 2021
    Released on J-STAGE: November 23, 2021
    JOURNAL FREE ACCESS

    This study investigates nodule deformation and contact area during PVA roller-type brush scrubbing to clarify their relationship with cross-contamination. Two high-speed video cameras with collimating LED light sources and an evanescent field on a prism enabled us to observe brush nodule deformation and contact area. Deformation analysis showed that the volume of a roller-type brush changes gradually at the beginning of compression, deforms more when vertically pushed at maximum compression, and then recovers rapidly at the end of compression. The brush contact area changes according to the brush and wafer rotation speed. The contact area can be categorized into three: the front, rear side face in the brush traveling direction, and vertically pushed bottom face on the surface. We analyzed the three types of brush contacts on a 100 mm type wafer and observed that the vertical compression type significantly affected the cross-contamination region.

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  • Yunosuke Norisada, Mizuho Kondo, Tomoyuki Sasaki, Moritsugu Sakamoto, ...
    2021 Volume 34 Issue 5 Pages 511-515
    Published: June 11, 2021
    Released on J-STAGE: November 23, 2021
    JOURNAL FREE ACCESS

    Thermally stimulated photoinduced molecular reorientation with high dichroism (D>0.6) is explored in liquid crystalline (LC) copolymerthacrylate films comprising of 4-methoxy-N-benzylideneaniline (MNBA) and benzoic acid (BA) side groups. Thermal hydrolysis of MNBA side groups induces free phenyl aldehyde (PA) side groups in the oriented film. Birefringence of the oriented films is adjusted by introducing 2,7-diaminofluorene (FL) to form new imine bonds with free PA side groups. Meanwhile, in situ exchange from MNBA to FL-based imine also controls the birefringence of the oriented film. The initial birefringence of the oriented copolymer film increases up to 0.22 after introducing oriented FL moieties.

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  • Mitsuhito Suwa, Toru Okazawa, Hideyuki Kobayashi
    2021 Volume 34 Issue 5 Pages 517-524
    Published: June 11, 2021
    Released on J-STAGE: November 23, 2021
    JOURNAL FREE ACCESS

    A siloxane oligomer (Si-OLIGO-1) was produced by introduction of a bifunctional alkoxysilane into a silsesquioxane composed of a trifunctional alkoxysilane. The oligomer, which can form a thick film, was synthesized by a sol–gel method. This organic/inorganic hybrid material had good transparency and heat resistance. Infrared absorption spectroscopic analysis indicated that Si-OLIGO-1 had a random structure with many acidic silanol groups capable of alkaline development. A novel negative photosensitive white decorative coating that consisted of Si-OLIGO-1 as the base resin and 40 wt% TiO2 (particle size 250 nm) as a white pigment was produced. The coating enabled facile complex decoration. A white cured film of thickness 10 µm had the brightness (L*) and color (a*, b*) required for the white frame of a display product. Although the coating did not transmit straight light of wavelength 300–700 nm, it gave a good patterning performance (resolution and pattern shape) on irradiation with ultraviolet light at a dose of 200–250 mJ/cm2. This is because it transmitted both g-line and h-line scattered light.

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  • Takuma Tsukada, Hideyuki Nakano
    2021 Volume 34 Issue 5 Pages 525-528
    Published: June 11, 2021
    Released on J-STAGE: November 23, 2021
    JOURNAL FREE ACCESS

    A novel emitting amorphous molecular material, 4-[bis(9,9-dimethylfluoren-2-yl)­amino]benzylideneaniline (BFBZA), was designed and synthesized. BFBZA provided moisture-sensitive hybrid film combined with benzoic acid (BA) that exhibited reversible change in emission color in response to moisture like as hybrid films of 4-[bis(4-methylpheyl)­amino]benzylideneaniline with pentafluorobenzoic acid (PFBA) and BA. On the other hand, another hybrid film of BFBZA combined with PFBA did not exhibit such reversible change in emission color. The balance of acidity level of organic acid and basicity level of the emitting amorphous molecular materials was suggested to play a role for exhibiting reversible change in emission color.

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  • Masahiro Furutani, Kako Maeno, Arata Tanaka
    2021 Volume 34 Issue 5 Pages 529-532
    Published: June 11, 2021
    Released on J-STAGE: November 23, 2021
    JOURNAL FREE ACCESS

    Anionic UV curing has been applied for many kinds of industrial resins, because it overcomes technical problems in conventional radical and cationic UV curing. In this study, a cystine-based latent curing reagent was designed, and synthesized from l- and d-cysteine. The reagents showed not only good solubility toward organic media, but also good thermal decomposition behavior in the presence of basic species. Using them with a photo-base generator and an epoxy resin having a disulfide bond, UV-cured films of B-to-3B grade of pencil-hardness were fabricated successfully, after 10 J/cm2 of 365 nm-light irradiation and subsequent heating at 120-160°C for 30 min. Furthermore, two glass substrates were adhered by using this anionic UV curing system, and 1.6-3.7 MPa of shear stress was recorded in the photo-adhesion and re-adhesion experiments.

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  • Shin-ichi Kondo, Naoki Doi, Yasushi Sasai, Yukinori Yamauchi, Masayuki ...
    2021 Volume 34 Issue 5 Pages 533-536
    Published: June 11, 2021
    Released on J-STAGE: November 23, 2021
    JOURNAL FREE ACCESS

    In this paper we studied on the size and morphology of polymer nano-film synthesized with the linker possessing the various length. Although the size measured by Zetasizer was larger than that by AFM, it was considered that polymer nano-film might be expanded due to solvation in PBS. The morphology of the polymer nano-film synthesized from succinic acid and glutaric acid showed square morphology rather than sphere. On the other hand, the polymer nano-film from azelaic acid showed spherical morphology. It was suggested that the difference among them might be ascribe to the flexibility of a polymer nano-film. Thus, the longer crosslinking chain length could be a more flexible polymer nano-film.

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  • Yuki Ogiwara, Naoto Iwata, Seiichi Furumi
    2021 Volume 34 Issue 5 Pages 537-542
    Published: June 11, 2021
    Released on J-STAGE: November 23, 2021
    JOURNAL FREE ACCESS

    In this study, we investigated the rheological behavior of a cholesteric liquid crystalline polymer prepared by esterification of hydroxyl propyl cellulose (HPC) with propionyl chloride. The HPC ester tethering propionyl side chains (HPC-Pr) showed thermotropic cholesteric liquid crystal (CLC) phase with visible Bragg reflection in the temperature range between 100 ºC and 135 ºC. Although visible Bragg reflection of HPC-Pr disappeared even after cooling from the temperature above isotropic phase transition temperature, we observed birefringence under crossed Nicols. Therefore, at this state, the molecular structure of HPC-Pr might be partially isotropic. The partially isotropic HPC-Pr had a relatively high viscosity as confirmed by rheological measurements. On the other hand, the viscosity decreased by shearing.

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  • Takaki Kaneda, Yutaro Seki, Naoto Iwata, Seiichi Furumi
    2021 Volume 34 Issue 5 Pages 543-548
    Published: June 11, 2021
    Released on J-STAGE: November 23, 2021
    JOURNAL FREE ACCESS

    In this report, we successfully fabricated the colloidal crystal (CC) gel films of silica microparticles combined with a temperature-responsive biocompatible hydrogel of poly(N-vinylcaprolactam) (VCL). When the CC VCL film was prepared by filling VCL precursor into the void space between silica particles of CC film, followed by the thermal polymerization, the Bragg reflection peak was red-shifted from 475 nm to 535 nm due to the change of refractive index contrast. Subsequently, immersion of the CC VCL film into an excess of water led to the formation of CC VCL gel film, wherein the VCL matrix swelled in water to form the hydrogel state. As elevating the temperature from 25 °C, this CC VCL gel film showed the reflection color changes from red to green, arising from the decrease of lattice constant induced by the shrinkage of VCL hydrogel. Moreover, the reflection color changes of CC VCL gel film were found to be fully reversible. In this way, we believe that such CC VCL gel films can be potentially applied to novel temperature sensors with biocompatibility.

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