A positive-type alkaline-developable photosensitive polyimide based on the poly(amic acid) from 2,2′,6,6′-biphenyltetracarboxylic dianhydride and 1,3-bis(4-aminophenoxy)benzene, and a diazonaphthoquinone

The synthesis of an alkaline-developable photosensitive polyimides (PSPI) based on a polyamic acid (PAA) was investigated. An alkaline developable PSPI based on PAA (PAA-BB) was derived from 2,2́,6,6́ biphthalic dianhydride (BPDA) and 4,4́-(1,3-phenylenedioxy)dianiline (1,3-APB), with a diazonaphthquinone derivatives (DNQ-1) as a dissolution inhibitor. The conversion of PAA into polyimides (PI) was carried out in a mixture of trifluoroacetic anhydride, pyridine, and toluene solution at room temperature. The photosensitivity and contrast of 1.3μm thick resist film consisting of PAA-BB (80 wt %) and DNQ-1 (20 wt %) produced a clear positive image with a 10μm line and space feature in a 2μm thickness. Results show that the dissolution rate of PAAs in 2.38 wt % aqueous tetramethylammonium hydroxide (TMAHaq) solution was high to get a contrast in dissolution rates when combined with DNQ derivatives.