Journal of Photopolymer Science and Technology
Online ISSN : 1349-6336
Print ISSN : 0914-9244
ISSN-L : 0914-9244
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Showing 1-17 articles out of 17 articles from the selected issue
  • Ayumi Kobayashi, Misaki Sou, Kohei Iritani, Seiji Bando, Takashi Yamas ...
    2020 Volume 33 Issue 5 Pages 479-484
    Published: July 01, 2020
    Released: July 01, 2020
    JOURNALS FREE ACCESS

    Owing to the paradigm shift in the development and utilization of energy systems from petroleum to electricity under social trend to realize sustainable society, the development of high-performance electrical devices has become increasingly important. Insulating materials are one of the key technologies for the practical application of next-generation electric devices because they must be driven at higher voltages but their complex shapes cannot be coated using current coating techniques. Therefore, the development of insulating materials with thermostability and facile electrodeposition ability is crucial for the production of high-performance next-generation electric devices. In this study, synthesis of novel polyimide with pendant dimethylaminobeonzoyloxy groups is described, with which hybrid electrodeposition coating with boehmite alumina was successfully obtained whose 10% weight loss temperature was 380 ℃.

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  • Sylvan Sunny Koyagura, Hiroaki Takehara, Takanori Ichiki
    2020 Volume 33 Issue 5 Pages 485-490
    Published: July 01, 2020
    Released: July 01, 2020
    JOURNALS FREE ACCESS

    This paper investigates the surface modification process of polydimethylsiloxane (PDMS) microchannels for the improvement of the image quality in dark-field imaging with light sheet illumination inside the microchannel. Dark-field light scattering technology in microchannels is a powerful technology used in the visualization of nanoparticles. Wet etching process using Tetrabutylammonium fluoride (TBAF) in N-methyl-2-pyrrolidinone (NMP) solvent was used for the surface modification of the PDMS microchannel, and the etch distance of PDMS with 0.68 M of TBAF in NMP solution for 10 min was evaluated as 18.8 ± 1.8 µm. Darkfield light scattering imaging of polystyrene nanoparticles (ϕ=100 nm) using light-sheet illumination was demonstrated and the attenuation of scattering light from the microchannel wall was confirmed using the microchannel with TBAF treatment. This surface modification technique improves the imaging quality with light sheet illumination.

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  • Jun Tanaka, Takuma Ishiguro, Tetsuo Harada, Takeo Watanabe
    2020 Volume 33 Issue 5 Pages 491-498
    Published: July 01, 2020
    Released: July 01, 2020
    JOURNALS FREE ACCESS

    EUV lithography is started to use in high volume manufacturing of 7-nm node semiconductor devices for smart phones. However, a resist development is still remained significant critical issue in EUV lithography. The EUV resist has to be achieved high resolution, high sensitivity, and low line-width roughness (LWR), simultaneously. Especially, the resist is required low LWR performance for a fine patterning. To reduce LWR, it is significant to control and reduce the stochastic behavior of the resist chemical contents such as the functional groups, photo reactive compound (photoacid generators:PAG), additives such as amines and so on. However, there is no method to measure the chemical contents spatial distribution. Therefore, the resonant soft X-ray scattering (RSoXS) method is applied to evaluate the chemical contents spatial distribution. Around the carbon absorption edge, the resonant absorption peaks are specific to the chemical contents of carbon. In RSoXS method, the soft X-ray scattering intensity from the resist is recorded by a CCD camera, which the incident photon energy irradiate to the resist sample is varied around the carbon absorption K-edge of 284 eV. If these chemical contents have large dispersion, the stochastic becomes worth. In this way, the chemical contents spatial distribution in photoresists is measured by RSoXS method, and this method is significant for development of low LWR resist.

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  • Yasufumi Kawasuji, Akira Suwa, Masakazu Kobayashi, Junichi Fujimoto, K ...
    2020 Volume 33 Issue 5 Pages 499-504
    Published: July 01, 2020
    Released: July 01, 2020
    JOURNALS FREE ACCESS

    An organic build-up film or a single crystal silicon wafer is used as the substrate material for a semiconductor multi-die package. However, the cost of a single crystal silicon wafer is very high and miniaturization of the processing of an organic build-up film by a commonly used 355 nm UV laser has almost reached the limit due to its long wavelength. In this paper, we report on the microdrilling processability of less than 10 µm diameter of a build-up film using a 248 nm excimer laser with high photon energy (5–6.4 eV). The dependence of the taper angle on the fluence was evaluated, in addition to the processing rate for various via hole diameters using major commercial build-up films (Ajinomoto GY50, GX-T31, GX92). The results of this study indicate the appropriate selection of build-up film material and excimer laser processing fluence to achieve the processing target diameter and taper angle. The micromachining of a build-up film by excimer lasers is thus expected to be widely used in future semiconductor packages due to their low cost and fine processing performance.

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  • Ruito Hashimoto, Minh Anh Truong, Anesh Gopal, Alwani Imanah Rafieh, T ...
    2020 Volume 33 Issue 5 Pages 505-516
    Published: July 01, 2020
    Released: July 01, 2020
    JOURNALS FREE ACCESS

    A series of polymers composed of partially oxygen-bridged triphenylamine units was successfully synthesized by Suzuki-Miyaura or Migita-Kosugi-Stille cross coupling reactions. In addition to the polymer with directly connected triphenylamine units, P1, different π-spacers, were introduced into the polymer main chains including m-benzene, P2, p-benzene, P3, and bithiophene, P4. Photoelectron yield spectroscopy (PYS) results showed that the highest occupied molecular orbitals of these polymers lie above the valence bands of typical metal halide perovskites, suggesting efficient hole extraction from the perovskite. When used as hole-transporting materials in perovskite solar cells, the maximum power conversion efficiency (PCE) of P1–P4 reached 7.9% with LiTFSI additive, while the device of P1 and P4 without additive showed better PCE of 12.1% and 11.1%, respectively.

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  • Takahiko Hariyama, Yasuharu Takaku, Chiyo Senoh, Satoshi Yamada, Toshi ...
    2020 Volume 33 Issue 5 Pages 517-522
    Published: July 01, 2020
    Released: July 01, 2020
    JOURNALS FREE ACCESS

    Scanning electron microscopy (SEM) has made a remarkable progress and is an essential tool for observing biological materials at microscopic level. However, various complex procedures have precluded observation of living organisms to date. Our recent discovery of a method coined the “NanoSuit®” is presented by which living organisms can be observed in a simple procedure by an SEM, which acts as a barrier to the passage of gases and liquids and thus protects the organism. Based on this discovery, we invented the coating method by the “biomimetic extracellular substances (ECS)” composed of biocompatible polymers for the organism which lack the natural ECS. The new “NanoSuit®” methods will be useful for medical and industrial applications.

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  • Seongjun Jo, Yeongsik Kim, Seungyun Jo, Kyungkon Kim, Du Yeol Ryu
    2020 Volume 33 Issue 5 Pages 523-528
    Published: July 01, 2020
    Released: July 01, 2020
    JOURNALS FREE ACCESS

    Partial fluorination of polystyrene-b-poly(tert-butyl methacrylate) (PS-b-PtBMA) copolymer was carried out to form PS-b-P(tBMA-r-TFEMA-r-MAA), where TFEMA and MAA denote 2,2,2-trifluoroethyl methacrylate and methacrylic anhydride units, respectively. Phase transitions of a partially (40%) fluorinated copolymer were investigated both in bulk and film using X-ray scattering techniques. The bulk transition pathways showed lamellae to hexagonally perforated layer (HPL) to gyroid (GYR) as temperature increases, although the volumetric ratio between the two blocks is still close to symmetric composition. Meanwhile in copolymer film, the interfacial interactions at air surface altered temperature-increasing transition pathways including HPL to hexagonally modulated layer (HML). However, the suppressed GYR was recovered in isothermal condition of HML at 240 ℃, while remaining the same HPL in isothermal condition at 140 ℃, indicating that a HML is less stable in thick films.

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  • Lei Dong, Alvin Chandra, Kevin Wylie, Ryuichi Nakatani, Yuta Nabae, Te ...
    2020 Volume 33 Issue 5 Pages 529-536
    Published: July 01, 2020
    Released: July 01, 2020
    JOURNALS FREE ACCESS

    In this study, side chain liquid crystalline (SCLC) fluorinated functionalities capable of controlling the orientation of the block copolymer (BCP) domains in thin film were successfully demonstrated. By introducing 1H,1H,2H,2H-perfluorodecanethiol onto a precursor polymer to obtain a novel BCP with a C8F17-containing LC side chain, BCP domains in 6.3-36.3 nm scale were obtained. For the studied symmetric SCLC diblock copolymers, a morphology transition from lamellae to cylinder was observed with reduced molecular weight (Mn). A co-existed 3.6 nm periodicity from lamellar smectic phase of SCLC was also verified in all synthesized BCPs of varied Mn by comprehensive characterizations of small angle X-ray scattering (SAXS) and wide angle X-ray diffraction (WAXD), differential scanning calorimetry (DSC) and polarized optical microscopy (POM). Atomic force microscopy (AFM) of the thin films revealed the formation of fingerprint patterns with increased correlation length when the domain spacing of the BCP is closer to the periodicity of the smectic structures, which are supported by the quantitative analysis on AFM images.

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  • Guangya Wu, Hai Deng
    2020 Volume 33 Issue 5 Pages 537-540
    Published: July 01, 2020
    Released: July 01, 2020
    JOURNALS FREE ACCESS

    A series of fluorinated block copolymers (BCPs) with ferrocene-containing block were synthesized via reversible addition-fragmentation chain-transfer polymerization. Highly ordered lamellar or hexagonal homogeneous ferrocene containing domains were observed by TEM. The smallest domain spacing measured by SAXS was 9.8 nm. Benefiting from the intrinsic etch resistance from the metallic domains, a high etch resistant BCP with 5 nm patterning capability was obtained.

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  • Le Dai, Hui Cao, Hai Deng
    2020 Volume 33 Issue 5 Pages 541-544
    Published: July 01, 2020
    Released: July 01, 2020
    JOURNALS FREE ACCESS

    Block copolymers composed of cinnamate or biphenyl liquid crystal and fluorinated side chain blocks were synthesized by RAFT polymerization. The block copolymers (BCPs) showed sharp phase separation benefit from the chemistry incompatibility of the fluorinated and the liquid crystal blocks. Both cinnamate and cyano-biphenyl liquid crystal containing BCPs formed highly ordered nanostructures with domain-spacing ranged from 15.6 nm to 12.4 nm. UV exposure could alter the cinnamate containing domain morphology via partially dimerization.

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  • Kazuki Honjo, Atsuhiro Furuta, Jun Taniguchi
    2020 Volume 33 Issue 5 Pages 545-550
    Published: July 01, 2020
    Released: July 01, 2020
    JOURNALS FREE ACCESS

    Demand for printed electronic devices is increasing, likewise the attention being paid to through-hole electrodes as an integration approach. In comparison with wire bonding integration methods, through-hole electrodes occupy smaller surface areas and have lower power consumption rates. Generally, the diameters of through-holes fabricated in flexible substrates are larger than those developed in rigid substrates. In this study, ultraviolet nanoimprint lithography was used to fabricate microscale through-holes in a flexible substrate, and these holes were subsequently filled with silver ink to form through-hole electrodes.

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  • Shingo Shimizu, Hideki Tanabe, Masaaki Yasuda, Yoshihiko Hirai, Hiroak ...
    2020 Volume 33 Issue 5 Pages 551-556
    Published: July 01, 2020
    Released: July 01, 2020
    JOURNALS FREE ACCESS

    Fine nickel (Ni) patterns were fabricated using the electroless plating. Poly(methyl methacrylate) (PMMA) patterns fabricated by the thermal nanoimprint lithography were used for the Ni pattern fabrication. Two processes, which were the “reverse pattern process” and the “same pattern process”, were developed. By the “reverse pattern process”, Ni pattern with the reverse to the PMMA pattern could be obtained. By the “same pattern process”, the same Ni pattern as the PMMA pattern could be obtained. Only by a slight process change, two different Ni patterns could be obtained from the same PMMA pattern. Silicon patterns were fabricated by plasma etching using the fabricated Ni patterns as an etching mask. By the “reverse pattern process”, good Si line and space pattern with about 0.2 μm width was successfully fabricated. By the “same pattern process”, a Si line and space pattern with about 0.2 μm width was also obtained, but its line edge roughness was large.

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  • Yasuhiro Matsuda, Hiroshi Kigami, Noriyuki Unno, Shin-ichi Satake, Jun ...
    2020 Volume 33 Issue 5 Pages 557-562
    Published: July 01, 2020
    Released: July 01, 2020
    JOURNALS FREE ACCESS

    A refractive index matching method in water to measure the velocity field around micro-pillars was investigated. The micro-pillars were fabricated from an optical material whose refractive index was 1.333, which is the same as that of water. The fabrication method used was UV imprint lithography (UV-NIL) with photolithography with a replica mold. The moving tracer particles on the pillars were measured by micro-digital holographic particle tracking velocimetry (micro-DHPTV). Because the refractive indices of the pillars and water were the same, the hologram images could be obtained clearly without diffraction around the micro-pillars. As a result, tracking of particles and measurement of velocity fields using reconstructed particles could be achieved without optical distortion. The moving particles could be captured around the micro-pillars.

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  • Yusuke Tsuda, Koki Hara
    2020 Volume 33 Issue 5 Pages 563-567
    Published: July 01, 2020
    Released: July 01, 2020
    JOURNALS FREE ACCESS

    The novel polyimides containing perfluoroalkyl group on their side chain were synthesized using the novel diamine monomers containing perfluoroalkyl group. The films of obtained polyimides on glass substrates were prepared and the surface wettability of these films were measured before and after UV (ultraviolet) light irradiation (254 nm). The water contact angles of these polyimide films were changed from about 113° to 56° by UV light irradiation. The novel polyimides containing both perfluoroalkyl group and spiropyran group was synthesized by introducing spiropyran group by Mitsunobu reaction with base polyimide containing phenolic OH group. The surface wettability of the polyimide film containing the spiropyran group changes from about 114° to about 104° by irradiation of UV light (365 nm), and reversibly changes from about 104° to about 114° by irradiation of Vis (visible) light.

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  • Hideyuki Kobayashi, Yusuke Fukuzaki, Mitsuhito Suwa
    2020 Volume 33 Issue 5 Pages 569-572
    Published: July 01, 2020
    Released: July 01, 2020
    JOURNALS FREE ACCESS

    New self-luminous displays such as organic light-emitting diode and micro light-emitting diode devices are attracting increasing attention. Moreover, many researchers are working to improve the light extraction efficiency of these devices to increase the display brightness. Proposed light extraction methods include refractive index control layers, controlled surface texture structures, and light-diffusion layers. Of these, our focus was on the light-diffusion layer, which requires suitable light diffusion, high transparency, high light resistance, and patternability for forming wiring connection areas. In this paper, we introduce novel photosensitive siloxane coatings using positive-tone photosensitive siloxane and a light-diffusion filler (TiO2 or ZrO2). These coatings control the haze value in the range of 5% to 72% in the form of a thin film (1 µm). In addition, the films have a high transparency, good light resistance, and appropriate patternability. Therefore, these photosensitive siloxane coatings with light-diffusion properties are suitable for new self-luminous displays.

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  • Takahiro Komamura, Koei Azuma, Yuta Nabae, Teruaki Hayakawa
    2020 Volume 33 Issue 5 Pages 573-582
    Published: July 01, 2020
    Released: July 01, 2020
    JOURNALS FREE ACCESS

    Mesoporous polyimide composite films were fabricated by a soft template method using a microphase-separated structure of an amphiphilic block copolymer and porosification by ozonolysis. Poly(1,4-isoprene)-block-poly(2-vinylpyridine) was used as the template block copolymer. Poly(amic acid) (PAA), the precursor of polyimide, and resol, the cross-linker for stabilization of the nanostructure, were miscible into the poly(2-vinylpyridine) domain which is the hydrophilic domain of the template block copolymer. The mixture co-assembled and formed a periodic body-centered cubic nanostructure. The study of ozonolysis condition revealed that the reaction in hexane allowed porosification without the collapse of the nanostructure. Polyimide composite films with well-defined mesopores were successfully obtained by the sequential processes of the PAA composite film, namely, thermal annealing for crosslinking of resol, ozonolysis in hexane for the decomposition of polyisoprene domain, and thermal treatment for imidization of PAA. The domain spacing determined by small-angle X-ray scattering was 28.8 nm, and the average pore size based on scanning electron microscopy was 24 nm.

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  • Koichiro Muto, Eisuke Fujiwara, Ryohei Ishige, Shinji Ando
    2020 Volume 33 Issue 5 Pages 583-590
    Published: July 01, 2020
    Released: July 01, 2020
    JOURNALS FREE ACCESS

    Pressure-induced variations in the crystalline structures of polyimides (PIs) that have flexible ether or thioether linkages along the main chain were analyzed by synchrotron wide-angle X-ray diffraction at high pressures up to 2.0 GPa. The crystalline lattices of poly(4,4-oxidiphenylene pyromellitimide) (PMDA/ODA) and poly(4,4'-diamino-diphenyl sulfide pyromellitimide) (PMDA/SDA) PIs that have one flexible linkage in their repeating unit showed negative linear compressibility along the main-chain direction (c-axis), with a large anisotropy in the compressibilities between the two interchain directions (a- and b-axes). In contrast, polyimides prepared from bis(4-aminophenyl) ether (PMDA/TPE) and 4,4'-bis(4-aminophenoxy) biphenyl (PMDA/BAPB) that have two flexible linkages in their repeating units exhibited positive compressibility along the main-chain direction, with a small difference in compressibility between the interchain directions. The different compression behaviors of PI crystalline lattices can be explained by the intrinsic Λ-shaped conformation of PMDA/ODA and PMDA/SDA, specifically the rotational fluctuations of the phenyl groups of the diamine moiety that were induced by the applied pressure.

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