Photosensitive polycarbonates based on reaction development patterning (RDP)

Films of commercially available poly(bisphenol A carbonate) (BPA-PC) and poly[bisphenol A carbonate-co-4,4'-(3,3,5-trimethylcyclohexylidene)diphenol carbonate] (BPA-TMC-PQ containing photosensitive agent (diazonaphthoquinone (DNQ) compound) were prepared by spin-coating onto copper foil. The obtained films showed positive-tone behavior by UV irradiation and following development with ethanolamine/N-methylpyrrolidone (NMP)/H2O mixture (1/1/1 by weight). The scanning electron microscope (SEM) photographs of the resulting images exhibited fine patterns (similar to 10 mum line/space resolution) with 15-16 mum film thickness. The pattern forming mechanism is based on the Reaction Development Patterning (RDP), in which the carboxylic acid resulting from photo-rearrangement of DNQ in the film attracts ethanolamine in the developer and the amine reacts with carbonate in the main chain to induce degradation of the polymer. RDP, where the main pattern forming reaction occurs during the development, is proved to be efficient for polycarbonates as well as polyimide.