Development of Photosensitive Poly(hydroxyimide) with High Refractive Index

A positive-type chemically amplified photosensitive poly(hydroxyimide) (PSPHI) based on the partially imidized poly(hydroxyimide) (PHI) prepared from 4,4'4-[p-thiobis(phenylenesulfanyl)]diphthalic anhydride and bis(3-amino-4-hydroxyphenyl)sulfone, 9,9-bis[4-(tert-butoxycarbonyl-methyloxy)phenyl]fluorene (TBMPF) as a dissolution inhibitor, and (5-propylsulfonyloxyimino-5H-thiophen-2-ylidene)-(2-methylphenyl)acetonitrile (PTMA) as a photoacid generator has been developed. This PSPHI consisting of the partially imidized PHI (80wt%), TBMPF (16 wt%), and PTMA (4 wt%) showed high transparency in the 450 nm wavelength and high refractive index of 1.698 and low birefringence of 0.0025. The PSPHI exhibited high sensitivity of 25 mJ/cm(2) and high contrast of 8.4 when it was exposed to a 436 nm line (g-line), post-exposure baked at 130 degrees C for 2 min, and developed with an aqueous alkaline developer, 2.38 wt% tetramethylammonium hydroxide solution/10 wt% iso-propanol at 25 degrees C. A clear positive pattern of 4 mu m line and space was obtained on a film exposed to 50 mJ/cm(2) of g-line by a contact printing method.