FLUORINE-CONTAINING PHOTOREACTIVE POLYIMIDES .7. PHOTOCHEMICAL-REACTION OF PENDANT 1,2-NAPHTHOQUINONE DIAZIDE MOIETIES IN NOVEL PHOTOREACTIVE POLYIMIDES

Novel photoreactive polyimides with 1,2-naphthoquinone diazide (NQD) groups in the side chain were synthesized by esterification of the hydrophilic polyimide, which had been prepared by the polycondensation of a fluorinated acid dianhydride and diamine with various amounts of NQD. These polyimides showed unique lithographic behavior. Either positive behavior was observed with an aqueous base developer or negative behavior could be achieved with an organic solvent developer, depending on the content of NQD. The reaction leading to the negative-working mode resulted from the low content of absorbed water in the hydrophobic fluorinated polyimide film. The cross-linking reactions leading to insolubility were a coupling reaction of the ketene and the reaction of a ketocarbene and a ketene, which are unstable intermediates in the photochemical reaction of NQD. It was further found by the study of water diffusion in the fluorinated polyimide film that the time needed to reach equilibrium with the surrounding atmosphere is shorter than 1.3 s for a dry 5μm-thick film of the fluorinated polyimides. © 1990, American Chemical Society. All rights reserved.