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
  • Yuji Shibasaki, Yutaro Kobayashi, Yumi Fujiwara, Tadashi Tsukamoto, Yo ...
    2024 Volume 37 Issue 1 Pages 1-6
    Published: May 31, 2024
    Released on J-STAGE: May 31, 2024
    JOURNAL FREE ACCESS

    Highly transparent thermally stable semi-aromatic poly(amide–imide)s (PAI)s were successfully prepared utilizing a diimide-dicarboxylic acid monomer, 2,2’-bis(trifluoromethyl)-4,4’-bis(trimellitimidophenyl)biphenyl (BTFTB), by direct polycondensation with aromatic, semi-aromatic, aliphatic, and alicyclic diamines in N-methyl-2-pyrrolidinone (NMP) with diphenyl (2,3-dihydro-2-thioxo-3-benzoxazolyl) phosphonate (DBOP) as a condensation agent in good yield (68 – 96%). The resulting PAIs, whose number-average molecular weights were up to 85,000 Da, showed good solubility in various organic solvents such as NMP, N,N-dimethylacetamide (DMAc), and tetrahydrofuran depending on the structure. The prepared films showed the good thermal stability (glass transition temperature (Tg) 236 – 314 °C), good mechanical properties (tensile strength up to 148 MPa, elongation at break 1.2 – 7.2%, and tensile modulus 1.7 – 4.3 GPa), and excellent optical transparency (cut-off wavelength (λcut) 322 – 405 nm). While these PAIs showed comparable thermal and mechanical properties and solubility with wholly aromatic PAIs such as poly(BTFTB-ODA) and poly(BTFTB-BAFL), they showed superior optical properties.

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  • Yuji Shibasaki, Haruki Sasaki, Ryota Shibata, Tadashi Tsukamoto, Yoshi ...
    2024 Volume 37 Issue 1 Pages 7-13
    Published: May 31, 2024
    Released on J-STAGE: May 31, 2024
    JOURNAL FREE ACCESS

    High molecular weight tetraazacalix[2]arene[2]triazine-containing polyguanamines (c-PGs) were successfully prepared by the heterogeneous polymerization of tetraazacalix[2]arene[2]triazine dichloride with α,ω-alkylene diamines, and the properties were evaluated in detail to elucidate the interaction between the azacalixarene structure within the film. The prepared c-PG polymers showed superior thermal, mechanical, and optical properties compared with a PG polymer without the azacalixarene units. By the structural analysis, it was revealed that the c-PG film was effectively reinforced by a randomly oriented azacalixarene - azacalixarene interactions, which realized the above-mentioned unique properties.

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  • Hiroshi Kobayashi, Motoki Kataoka, Shogo Komiya, Tomoki Iwaoka, Kazuki ...
    2024 Volume 37 Issue 1 Pages 15-21
    Published: May 31, 2024
    Released on J-STAGE: May 31, 2024
    JOURNAL FREE ACCESS
  • Toshiyuki Minegishi, Atsushi Morikawa
    2024 Volume 37 Issue 1 Pages 23-28
    Published: May 31, 2024
    Released on J-STAGE: May 31, 2024
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  • Jiro Hikida, Yoshinori Tadokoro, Naohiko Ikuma, Dai Shiota, Tadashi Ts ...
    2024 Volume 37 Issue 1 Pages 29-34
    Published: May 31, 2024
    Released on J-STAGE: May 31, 2024
    JOURNAL FREE ACCESS

    Thermal-based generators (TBG) have recently attracted attention because they can imide polyamic acids with just a low-temperature heating process. Although it is possible to promote imidization with an amine compound, the container stability is poor and it is not suitable for industry. The thermobase generator 3-Imidazolyl-3-(4-methoxyphenyl)-propionic acid) (IMP), which generates imidazole (IM) by heating, was developed to promote imidization of polyamic acid (PAA) at low temperatures. Moreover, since it is not salt-forming, the storage stability of the PAA solution is high. In this study, we report that the mechanical properties equivalent to the high temperature process were obtained by the low temperature thermal process.

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  • Ayça Kurt, Ayşe Mete Atlas, İpek Arslan, Tamer Tüzüner, Özgül Baygın, ...
    2024 Volume 37 Issue 1 Pages 35-42
    Published: May 31, 2024
    Released on J-STAGE: May 31, 2024
    JOURNAL FREE ACCESS
  • Ali Kara, Aysu Alan, Nalan Tekin
    2024 Volume 37 Issue 1 Pages 43-55
    Published: May 31, 2024
    Released on J-STAGE: May 31, 2024
    JOURNAL FREE ACCESS

    The photocatalytic-poly(ethylene glycol dimethacrylate-co-4-vinylpyridine)-titanium dioxide (pho-poly(EGDMA-co-4-VP)-TiO2) nanocomposite beads prepared from copolymerizing of ethylene glycol dimethacrylate (EGDMA) with 4-vinylpyridine (4-VP). The synthesized nanocomposite beads were investigated as a novel photocatalytic adsorbent for the adsorption of Acid Violet 7 (AV7) dye molecules from aqueous solutions in this study. The pho-poly(EGDMA-co-4-VP)-TiO2 nanocomposite beads were characterized by N2 adsorption/desorption isotherms, elemental analysis, X-ray photoelectron spectrometry (XPS), scanning electron microscope (SEM), fourier transform infrared spectroscopy (FTIR), and swelling studies. The influence of initial solution pH, initial solution concentration, temperature, contact time to adsorption-desorption of the removal process was comprehensibly studied. The adsorption process was found to be optimal in the wide pH range of 2-9. The equilibrium adsorption data obtained was well described by the Langmuir isotherm model and adsorption kinetics followed a pseudo-second-order kinetic model, indicating that adsorption was the rate-limiting step. The nanocomposite beads could be regenerated by a treatment with 0.1M NaOH (up to ca. 92%). These features make the pho-poly(EGDMA-co-4-VP)-TiO2 nanocomposite beads potential supports for AV7 removal from aqueous solution.

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  • Yasuhiro Funayama, Rumana Nozawa, Ayumi Kobayashi, Kohei Iritani, Hide ...
    2024 Volume 37 Issue 1 Pages 57-62
    Published: May 31, 2024
    Released on J-STAGE: May 31, 2024
    JOURNAL FREE ACCESS

    To realize a sustainable growth society, automobiles are undergoing a shift from gasoline to electric vehicles, for which the development of a highly efficient small electric motor is critical. Recently, a rectangular motor coil with a high occupancy ratio has been developed, and an electrophoretic deposition-based coating method using polyimide (PI) has gained attention for forming an insulation film with high heat resistance. In this study, PI with methacrylic groups, PI(BPADA/AHPP), was synthesized and an electrophoretic deposition dispersion was prepared by nano-compositing it with alumina sol. The zeta potential of the dispersion was charged at +55.5 mV. A film of 122-μm thickness was deposited on the cathode via electrophoretic deposition using the dispersion. After baking, the insulating film exhibited high electrophoretic deposition ability and high heat resistance, as evidenced by the 10% weight loss temperature of 413 °C and the coulomb efficiency of 27 mg/C.

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  • Yasuhiro Funayama, Hisatora Takahashi, Ayumi Kobayashi, Kohei Iritani, ...
    2024 Volume 37 Issue 1 Pages 63-68
    Published: May 31, 2024
    Released on J-STAGE: May 31, 2024
    JOURNAL FREE ACCESS

    To realize sustainable societal growth, the automotive industry is currently transitioning from gasoline-powered vehicles to electric ones. Consequently, there is a growing need for the development of compact electric motors with high energy conversion efficiency. Although a rectangular motor coil with a high occupancy ratio has been developed, it is not easy to protect the surface of the coil using conventional dipping methods. As an alternative method, we previously proposed an electrophoretic deposition (EPD) method using polyimide (PI) with high heat resistance as an insulating material. An EPD material based on the ammonium salt of a polyamide acid PAA(PMDA/ODA) as PI precursor has been developed; however, it was subjected to hydrolysis, and the lifetime was quite low. Therefore, a polyamide ester, PAE(PMDA/ODA), was synthesized to protect the carboxylic acids in PAA. The EPD solution of PAE with boehmite alumina successfully resulted in a 53 µm thickness deposition coating by EPD. After baking the coating film for the imidization of PAE, we obtained a 10% weight-loss temperature and Coulomb efficiency of 580 °C and 82 mg/C, respectively, indicating high EPD ability and heat resistance.

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  • Ryoma Amanuma, Shun Fujihara, Ayumi Kobayashi, Kohei Iritani, Takashi ...
    2024 Volume 37 Issue 1 Pages 69-74
    Published: May 31, 2024
    Released on J-STAGE: May 31, 2024
    JOURNAL FREE ACCESS

    Recently, environmentally responsive hydrogels have gained significant attention owing to their ability to undergo substantial volume changes in response to external stimuli. This unique characteristic has sparked interest in exploring their potential applications in fields such as artificial actuators and sensors. In this study, we developed a fluorescent gel with tunable fluorescence wavelength by adjusting the mixing ratio of DMSO and H2O as solvents. To achieve this objective, we synthesized a gel comprising poly(N-Isopropylacrylamide) with a dimethylaminotolane carboxyl group at the side chain, exhibiting an aggregation-induced emission effect. Through the adjustment of solvent mixing ratio, we observed significant changes in the gel volume along with the modulation of fluorescence wavelength, probably depending on the aggregation state of the polymer chain.

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  • Kaito Yamada, Yoshihiko Hirai, Masaaki Yasuda
    2024 Volume 37 Issue 1 Pages 75-79
    Published: May 31, 2024
    Released on J-STAGE: May 31, 2024
    JOURNAL FREE ACCESS

    We have developed a molecular dynamics simulation that reproduces the pattern formation process of electron beam lithography for negative-type resists. Structural change of resist material by electron beam exposure was introduced as crosslinking between resist molecules. The crosslinks were formed at each position of the resist in proportion to the absorbed energy distribution obtained by the Monte Carlo simulation of electron scattering according to the electron exposure conditions. Development was reproduced by removing the low molecular weight resist molecules from the system. The pattern size obtained after development showed shrinkage due to the cohesive force acting between molecules. It was also shown that the undulations seen at the pattern edge are suppressed by the cohesive force and the pattern roughness is reduced.

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  • Akihiro Konda, Hiroki Yamamoto, Shusuke Yoshitake, Takahiro Kozawa
    2024 Volume 37 Issue 1 Pages 81-88
    Published: May 31, 2024
    Released on J-STAGE: May 31, 2024
    JOURNAL FREE ACCESS

    For the realization of further miniaturization at scale of 10 nm and below in semiconductor devices, it is essential to understand the dissolution kinetics of resist films in developer. In this study, the change in molecular weight and dissolution kinetics induced by ionizing radiation in poly(methyl methacrylate) (PMMA) resist films were studied using a quartz crystal microbalance method and gel permeation chromatography. The weight-averaged molecular weight Mw was changed from 50000 to 996000. Three types of developers (o-xylene and 1:3 and 1:7 mixing solutions of methyl isobutyl ketone and isopropanol) were examined. The kinetics during the development of PMMA films was classified into three patterns. In low Mw region, only dissolution was observed. In middle Mw region, both swelling and dissolution were observed. In high Mw region, only swelling was observed. The boundaries between regions were dependent of the developer and independent of the initial molecular weight of PMMA.

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  • Yosuke Ohta, Atsushi Sekiguchi, Shinji Yamakawa, Tetsuo Harada, Takeo ...
    2024 Volume 37 Issue 1 Pages 89-93
    Published: May 31, 2024
    Released on J-STAGE: May 31, 2024
    JOURNAL FREE ACCESS

    It has been reported that the good correlation in sensitivity and resolution between EUV exposure and EB exposure because of the similar mechanism of the photochemical-reaction in photoresists during exposure. However, in the early stages of EUV resist development, there are problems on the points of the cost and time-consuming to evaluate all EUV resist materials by EB exposure. Therefore, we investigated the possibility of using KrF exposure as the initial screening of EUV resists. In former report, we evaluated the correlation of sensitivity between KrF and EUV exposure, KrF and EB exposure, EB and EUV exposure respectively by using various type of resists. Then we could find there is some correlation between each exposure. In this report, we formulated some types of KrF resist and investigated whether there is a correlation of sensitivity between KrF and EUV exposures.

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  • Yusuke Fukuzaki, Manami Fujii, Mitsuhito Suwa
    2024 Volume 37 Issue 1 Pages 95-100
    Published: May 31, 2024
    Released on J-STAGE: May 31, 2024
    JOURNAL FREE ACCESS

    Optical sensors composed of microlenses and thin-film transistor sensors are attracting increasing attention for use in next-generation fingerprint sensing technology that is intended to achieve large-area fingerprint recognition. Such optical sensors would allow smartphones to recognize multiple fingers and thus increase their security level. In this paper, we introduce novel high-refractive-index photosensitive siloxane coatings. These coatings have a high reflowability that allows them to form microlenses by controlling the glass transition temperature, which is determined by the specific combination of difunctional units and trifunctional units used in the siloxane polymer. The coatings also have excellent optical properties, high heat resistance, and high heat stability. These promising features mean that the photosensitive coatings presented here are suitable for fabrication of microlenses for next-generation fingerprint sensors.

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  • Takashi Doi, Tsutomu Shimokawa
    2024 Volume 37 Issue 1 Pages 101-107
    Published: May 31, 2024
    Released on J-STAGE: May 31, 2024
    JOURNAL FREE ACCESS

    We had previously developed a novel negative tone-type photosensitive material that can be patterned by photolithography, based on a chemically amplified system containing a phenolic resin, a crosslinker, and a photochemical acid generator (PAG). It exhibits a low coefficient of thermal expansion and low residual stress after thermally treated at 260 °C. However, when photolithography was performed to form micro-scale hole patterns on a thin film of the photosensitive material, the resin’s high absorbance caused overhung profile was observed and which was considered to lead to difficulty in subsequent metal wiring formation on the film. In this study, the normally tapered pattern formation was tried by applying positive tone-type photosensitive materials. The hydroxy groups of phenolic resin were protected by acid cleavable and/or hydrophobic substituents and the protected resin was mixed with the PAG for creating the chemically amplified positive tone-type photosensitive material. We also investigated the photolithography, the effect of heat treatment conditions on residual stress, and the light transmittance and solvent solubility of the resins. We found that the substitution of the side groups with tert-butyl acetate was effective in the formation of normally tapered patterns by photolithography and observed low residual stress of the thin film after heat treatment at 260 °C. This material is a good candidate as an interlayer dielectric for semiconductor devices and wafer-level microfluidic materials for cooling semiconductor chips.

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  • Kyohei Imai, Bunta Inoue, Yoshihiko Hirai, Masaaki Yasuda
    2024 Volume 37 Issue 1 Pages 109-114
    Published: May 31, 2024
    Released on J-STAGE: May 31, 2024
    JOURNAL FREE ACCESS

    The pattern formation in a resist with photo-decomposable quencher (PDQ) by extreme ultraviolet (EUV) lithography was studied with stochastic simulation. The pattern shapes formed in the resist with the conventional quencher (Conv. Q) and the PDQ were compared. It was shown that a resist having a PDQ can suppress an increase in LER and CD errors with an increase in post exposure bake time as compared with the Conv. Q. It was also shown that the PDQ can form patterns with higher sensitivity. The formation of a 7 nm line pattern with a relatively excellent shape could be reproduced, and the effectiveness of the PDQ in the formation of a sub-10 nm pattern could be shown.

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  • Mei Yee Cheong, Wen Huei Lim, Zafarizal Aldrin Azizul Hasan
    2024 Volume 37 Issue 1 Pages 115-127
    Published: May 31, 2024
    Released on J-STAGE: May 31, 2024
    JOURNAL FREE ACCESS

    A new type of plant oil-based ultraviolet (UV)-curable oligomer has been synthesized and used in coating formulation. The trimethylolpropane (TMP) oleate was epoxidized and reacted with acrylic acid via ring-opened reaction to produce acrylated TMP oleate. The dwindling acid value and oxirane oxygen content indicated successful acrylation. The degree of acrylation obtained from the acrylated TMP oleate was 50.21%. The acrylated TMP oleate underwent UV-initiated polymerization with monomer, trimethylolpropane triacrylate (TMPTA) and a photoinitiator, 1-hydroxycyclohexyl phenyl ketone (Irgacure 184) in various ratio which resulted in radiation cured coating with acceptable properties, high crosslink density from the gel content and Konig pendulum hardness. The synthesized compound is a promising candidate to increase the biobased content of the existing UV curable compounds.

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  • Takahiro Kozawa
    2024 Volume 37 Issue 1 Pages 129-134
    Published: May 31, 2024
    Released on J-STAGE: May 31, 2024
    JOURNAL FREE ACCESS

    The trade-off relationships between resolution, line edge roughness (LER), and sensitivity are a serious problem in the extreme ultraviolet (EUV) lithography. The increase of pattern formation efficiency is essentially required to simultaneously improve these three properties. The pattern formation efficiency is determined by the factors such as the absorption coefficient, W-value, the reduction potential of acid generator, the effective reaction radius for deprotection, and the efficiency of solubility switching. Among them, the increase of effective reaction radius requires particular attention, because the stochasticity of protected units also increases with the effective reaction radius. In this study, the relationship between defect risks and effective reaction radius for deprotection of chemically amplified resists was investigated using a Monte Carlo simulation under the condition of maximum chemical gradient. LER had a minimum value approximately at the effective reaction radius of 0.3 nm. The pinching and bridging risks decreased with the increase of effective reaction radius to 0.5 nm. However, its effect on the pinching and bridging risks differently depended on the initial standard deviation and the total sensitizer concentration.

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  • Eunseok Lee, Yuko Ogata, Ryotaro Seto, Shunichi Himori, Hiroaki Gotoh
    2024 Volume 37 Issue 1 Pages 135-140
    Published: May 31, 2024
    Released on J-STAGE: May 31, 2024
    JOURNAL FREE ACCESS

    1-Hydroxycyclohexyl phenyl ketone (Omnirad 184), a photoinitiator that provides thermal stability and efficient photocleavage, is unsuitable for polymerization using light near 400 nm, typically generated by an LED lamp because Omnirad 184 shows less absorption for long-wavelength UV light. However, Omnirad 184 acquired a photosensitizing ability (under light near 400 nm) when a 1,4-dioxy-2-naphthoic acid derivative was added to it, affording accelerated polymerization, and enhanced final conversion. In this study, 1,4-dioxy-2-naphthoic acid derivatives were synthesized and their photosensitizing abilities were evaluated using Fourier transform infrared spectroscopy (FTIR). The results showed that phenyl 1,4-dihydroxy-2-naphthoate (DHNA-Ph) is the best photosensitizer. Quenching studies confirmed the interaction between the excited states of some 1,4-dihydroxy-2-naphthoic acid derivatives and Omnirad 184, which promotes the excitation of the latter. The results show that the interaction may involve electron transfer from the excited singlet state of the naphthoic acid derivatives to the initiator Omnirad 184. Although Omnirad 184 is a good photoinitiator, it cannot be used with a near UV and Visible LED (405 nm). This study aims to overcome this problem using different photosensitizers.

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  • Kazue Hirano, Masaya Toba, Masaki Yamaguchi
    2024 Volume 37 Issue 1 Pages 141-146
    Published: May 31, 2024
    Released on J-STAGE: May 31, 2024
    JOURNAL FREE ACCESS

    Semiconductor packages for high performance devices with printed circuit boards having multi wiring layers such as FC-BGA have been attracting the attention in order to realize ultra-reliable and low latency communications in 5G networking. Cu wirings for the package are usually fabricated by semi-additive process (SAP) with desmear process and/or modified semi-additive process (MSAP) by using Cu foil with large surface roughness. Though a desmear process and Cu foil can obtain enough adhesion between dielectric and Cu seed layer by anchoring effect to secure reliabilities, the interface between dielectric and Cu seed layer should be smooth to achieve low attenuation of electric signals at high frequencies. Here, instead of that processes, we applied an UV modification for the surface of our developed prepreg in order to realize a smooth and high adhesive seed layer against the dielectric. We also conducted chemical modification for the surface of Cu foil to achieve low attenuation of transmission loss and high adhesion against prepreg. We successfully assembled Cu wirings with L/S = 6/6 μm on prepregs by SAP. High peel strength between Cu foil and prepreg was obtained due to chemical modification for the surface of Cu foil. The normalized transmission loss of Cu wiring assembled through MSAP was improved as compared to Cu foil with rough surface.

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