Direct Patterning of Poly(amic acid) and Low-Temperature Imidization Using a Crosslinker, a Photoacid Generator, and a Thermobase Generator

A positive-type photosensitive polyimide (PSPI) based on poly(amic acid) (PAA), a crosslinker 1, 1, 1-tris[4-[2-(vinyloxy)ethoxy]phenyl}ethane (TVPE), a photo-acid generator (PAG) (5-propylsulfonyloxyimino-5H-thiophen-2-ylidene)-2-(methylphenyl) acetonitrile (PTMA), and a thermobase generator (TBG) t-butyl 2,6-dimethylpiperidine-1-carboxylate (BDPC) has been developed as a promising material in microelectronics. The PAA was prepared from 3,3',4,4'-biphenyltetracarboxylic dianhydride (BPDA) and 4,4'-oxydianiline (ODA) in dimethyl sulfoxide (DMSO). The PSPI, consisting of PAA (69 wt %), TPVE (21 wt %), PTMA (3 wt %), and BDPC (7 wt %), showed high sensitivity of 21 mJ/cm(2) and a high contrast of 6.8 when it was exposed to a 436-nm line (g-line), postbaked at 90 degrees C for 5 min, and developed with 1.69 wt % TMAHaq. A clear positive image of 8 pin line and space pattern was printed on film, which was exposed to 50 mJ/cm(2) of g-line by a contact printing mode and fully converted to the corresponding polyimide (PI) pattern on heating at 200 degrees C, confirmed by FTIR spectroscopy. Thus, this system will be a good candidate for next generation PSPIs. (C) 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chen) 47: 3362-3369, 2009