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Masking effect of photoactive compounds with various ballast molecules in novolak‐naphthoquinonediazide positive photoresists
Author(s) -
Kishimura Shinji,
Yamaguchi Atsumi,
Yamada Yoshiaki,
Nagata Hitoshi
Publication year - 1992
Publication title -
polymer engineering and science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.503
H-Index - 111
eISSN - 1548-2634
pISSN - 0032-3888
DOI - 10.1002/pen.760322019
Subject(s) - ballast , materials science , molecule , masking (illustration) , chemical engineering , nanotechnology , polymer chemistry , organic chemistry , chemistry , art , ecology , engineering , visual arts , biology
Abstract We investigated the masking effect, that is, the dissolution inhibition effect, of photoactive compounds (PAC) with various ballast moelcules in novolak‐naphthoquinonediazide positive photoresists. Two types of ballast molecules were examined: hydroxybenzophenones (HBP) and several m‐cresol novolak resins (MCN) of different molecular lengths. The number of naphthoquinonediazide sulfonic (NQDS) moieties in the resist film and the average esterification value of the PACs were the same for each type of ballast molecule. The smaller the size of the HBP ballast molecule, the larger the masking effect becomes. As the size of the ballast molecule becomes smaller, the number of PACs increases and the degree of dispersion of the NQDS moieties in the resist film increases. At the same time, the longer the MCN ballast molecule, the larger the masking effect becomes. The distance between the NQDS moieties in the MCN ballast molecule is greater than that in the HBP ballast molecule. The masking effect per NQDS moiety in the MCN ballast molecule is larger than that in the HBP ballast molecule. As a result, the distance between the NQDS moieties in the ballast molecule and the degree of dispersion of the NQDS moieties in the resist film control the masking effect, which depends on the probability of existence of NQDS moieties around the alkali‐soluble hydroxyl groups of the novolak resin. The molecular length of the ballast molecule influences the degree of entanglement with the novolak resins and promotes the masking effect.