New base-soluble positive-working photosensitive polyimides having o-nitrobenzyl ester group

Authors

  • Kyong Ho Choi,

    1. Center for Advanced Functional Polymers, Polymer Research Institute, Department of Materials Science & Engineering, Pohang University of Science & Technology (POSTECH), San 31, Hyoja-dong, Pohang, 790-784 Korea
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  • Jin Chul Jung,

    Corresponding author
    1. Center for Advanced Functional Polymers, Polymer Research Institute, Department of Materials Science & Engineering, Pohang University of Science & Technology (POSTECH), San 31, Hyoja-dong, Pohang, 790-784 Korea
    • Center for Advanced Functional Polymers, Polymer Research Institute, Department of Materials Science & Engineering, Pohang University of Science & Technology (POSTECH), San 31, Hyoja-dong, Pohang, 790-784 Korea.
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  • Kyoung Seon Kim,

    1. Department of Chemistry, Korea Advanced Institute of Science & Technology, 373-1, Guseong-dong Yuseong-gu, Daejeon, 305-710 Korea
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  • Jin Baek Kim

    1. Department of Chemistry, Korea Advanced Institute of Science & Technology, 373-1, Guseong-dong Yuseong-gu, Daejeon, 305-710 Korea
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Abstract

A new positive-working polyimide having photosensitive o-nitrobenzyl ester group as side substituent, poly{1,4-phenyleneoxy-1,4-phenylene-3,6-di[4-(o-nitrobenzyloxy)carbonylphenyl]pyromellitimide} (ODA-PI-Nb), was prepared and its aqueous alkali-developability and photosensitivity were investigated. ODA-PI-Nb was synthesized by the esterification reaction of poly[1,4-phenyleneoxy-1.4-phenylene-3,6-di(4-carboxylphenyl)pyromellit imide] (ODA-PI) with o-nitrobenzyl bromide in the presence of triethylamine (Et3N). ODA-PI-Nb obtained was characterized by FT-IR and 1H-NMR spectroscopy. The degree of esterification reaction was found from 1H-NMR absorption of CH2 proton to be over 95 mol%. Upon photo-irradiation ODA-PI-Nb transformed to the freely aqueous alkali-soluble ODA-PI under formation of o-nitrosobenzaldehyde. The thickness loss of thin ODA-PI-Nb films upon post-baking at 400°C was in the 10–15% range. ODA-PI-Nb showed positive-tone behavior in characteristic sensitivity curve and positive patterns were obtained using a typical lithographic process using aqueous tetramethylammonium hydroxide developer. The patterns with excellent resolution were observed and evaluated by optical microscopy and scanning electron microscopy. Copyright © 2005 John Wiley & Sons, Ltd.

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