Development of a Chemically Amplified Photosensitive Polyimide Based on Poly(amic acid), a Dissolution Inhibitor, and a Photoacid Generator

A chemically amplified photosensitive polyimide (PSPI) based on poly(amic acid) (PAA), 9,9-bis[4-(tert-butoxycarbonylmethyloxy)phenyl]fluorene (TBMPF) as a dissolution inhibitor, and (5-propylsulfonyloxyimino-5H-thiophene-2-ylidene)-(2-methylphenyl)actonitrile (PTMA) as a photoacid generator has been developed. The PAA was prepare from 4,4'-(hexafluoroisopropylidene)diphthalic anhydride (6FDA) and 2,2-bis[4-(aminophenoxy)phenyl]hexafluoropropane (6FAPP). The PSPI consisting of PAA (84 wt%), TBMPF (8 wt%), and PTMA (8 wt%) showed high sensitivity of 45 mJ/cm2 and high contrast of 12, when it was exposed to a 435 nm line (g-line), postbaked at 110 °C for 2 min, and developed with an aqueous alkaline developer, 2.38 wt% tetramethylammonium hydroxide solution with 5 wt% iso-propanol at 25 °C. A clear positive image of 4μm line and space pattern was printed on a film exposed to 200 mJ/cm2 of g-line by a contact printing method and converted into the polyimide pattern upon heating at 250 °C for 1 h.