High aspect ratio patterning of photosensitive polyimide with low thermal expansion coefficient and low dielectric constant

摘要

A photosensitive polyimide system based on amine catalyzed imidization of a precursor poly(amic ester) is described. The material is based on the meta ethyl ester of pyromellitic dianhydride and 2,2′ bis(tri-fluoromethyl)benzidine. It acts as a negative tone resist when formulated with a photobase generator. The material exhibits a dielectric constant of 3.0 in the gigahertz range, a coefficient of thermal expansion of 6 ± 2 ppm/K, and can be patterned to aspect ratios of ＞2 when formulated with a highly quantum efficient cin-namide type photobase generator.