New negative-type photosensitive polyimide based on hyperbranched poly(ether imide), a cross-linker, and a photoacid generator

A new negative working photosensitive polyimide, based on hyperbranched poly(ether imide) (1), 4,4 ' -methylenebis[2,6-bis(hydroxymethyl)]phenol (2) as a cross-linker, and a photoacid generator diphenyliodonium 9,10-dimethoxyanthracene2-sulfonate (3) has been developed. I was prepared by polycondensation of N-[3,5-di-(tert-butyldimethylsilyloxy)phenyl]-4-fluorophthalimide (4), followed by deprotection of tert-butyl-dimethylsilyl group with KF-HBr. The photosensitive polyimide containing 1 (70 wt%), 2 (20 wt%) and 3 (10 wt%) gave a clear negative pattern when it was exposed to 365 nm light and postbaked at 120 degreesC, followed by developing with a 2.38 wt% aqueous tetramethylammonium hydroxide (TMAH) solution at room temperature.