Photoresists based on a novel photorearrangement of o-nitrobenzylic polymers
A new photosensitive dicarboxylic acid, isophthalimido bis(α-methylamino-2-nitro-4-toluic acid)(4) was synthesized and characterized. Copolymerization of the corresponding acid chloride with diamines gave polyamides having photo-sensitive o-nitrobenzylic chromophores at symmetrical positions of every repeating unit. Photolysis of the new poly-amides resulted an interesting photorearrangement leading to the formation of azo polymers with carboxylic acid groups at the ortho positions. The polarity difference induced by the photorearrangement brings about a solubility difference between the irradiated and unirradiated polymers, which renders them useful as positive photoresist materials.