Novel photosensitive polymer based on polycarbodiimide and photoamine generator

A novel photosensitive polymer based on end-capped polycarbodiimide (E-PCD) and the photoamine generator N-{[(4,5-dimethoxy-2-nitrobenzyl)oxy]carbonyl}-2,6-dimethylpiperidine (1) was developed. The E-PCD was prepared by polycondensation of tolylene-2,4-diisocyanate in the presence of 3-methy-1-phenyl-2-phospholene-1-oxide as a catalyst. The reaction of carbodiimide and secondary amine was studied. The nucleophilic addition of amine to the carbodiimide moiety proceeded smoothly and provided a guanidine base that acted as a crosslinking agent. A lithographic evaluation of the system of E-PCD and 1 revealed that the dissolution rate of the exposed area after the postexposure bake decreased drastically, although no obvious change of the dissolution rate in the unexposed area was observed. The E-PCD containing 10 wt % 1 functioned as a negative working photosensitive polymer when it was exposed to 365-nm UV light, postbaked at 120 °C for 5 min, and developed with toluene at 25 °C.