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A water‐developable negative photoresist based on the photocrosslinking of N ‐phenylamide groups with reduced environmental impact
Author(s) -
Chae Kyu Ho,
Sun Gum Ju,
Kang Jin Koo,
Kim Taek Hyeon
Publication year - 2002
Publication title -
journal of applied polymer science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.575
H-Index - 166
eISSN - 1097-4628
pISSN - 0021-8995
DOI - 10.1002/app.11060
Subject(s) - copolymer , photoresist , polymer chemistry , aqueous solution , solubility , irradiation , chemistry , materials science , photochemistry , polymer , organic chemistry , physics , layer (electronics) , nuclear physics
A water‐developable negative photoresist based on the photocrosslinking of N ‐phenylamide groups was prepared by the copolymerization of 4‐styrenesulfonic acid sodium salts (SSS) with N ‐phenylmethacrylamide (copolymer A) or p ‐hydroxy‐ N ‐phenylmethacrylamide (copolymer B), and its properties such as solubility changes, photochemical reaction, and photoresist characteristics were studied. The copolymer containing a relatively higher amount of SSS units was soluble in water. Solubility changes of the copolymers in the various buffer solutions of pH 4 ∼ 11 and in water upon irradiation were observed by the measurement of insoluble fraction. The copolymers were soluble in water before irradiation, whereas they became insoluble upon irradiation with the UV light of 254 nm. The photochemical reaction of the copolymer studied by the UV and IR absorption spectroscopies indicated that a photo‐Fries rearrangement was favored for copolymer A, whereas a photocrosslinking reaction was predominate for copolymer B. Resist properties of the copolymers were studied by measurement of the normalized thickness and by development of the micropattern. Negative tone images with a resolution of 1 μm were obtained with these materials that have a sensitivity ( D 0.5 g ) of ∼ 1100 mJ/cm 2 with an aqueous developing process.© 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 1172–1180, 2002