Solubility enhancement for poly(amic acid)s by rapid hydrolysis of the polymer main chain during alkaline development

In an alkaline developer carboxyl containing polymer films possess a higher critical carboxyl group concentration (CGC(0)) below which dissolution doe s not occur, compared with novolac resins, therefore, it is difficult to ob tain the polymer film with a lower dissolution rare and less swelling. We d escribe herein a new approach for reducing CGC(0) of carboxyl containing po lymers by introducing an ester group which is labile in the alkaline develo per within the time-scale of development to obtain the polymers with modera te dissolution rates and less swelling. The rapid hydrolysis that leads to polymer degradation is clearly verified by gel permeation chromatography (G PC).