Chemically amplified resists (CARs) have played an important role in the advancement of photolithography and indirectly, the advancement of semiconductor technology. The design of CARs is based on photogeneration of acid catalysts that mediate chain reactions. This design offers very high radiation sensitivity but it suffers from the conflict between a requirement for efficient diffusion of the acid catalyst to provide high photosensitivity and the problems of bias, image blur and line edge roughness (LER) that are the direct result of the acid diffusion. The goal of this work is to design a resist has high radiation sensitivity that does not employ a catalyst and therefore, does not suffer from the resolution and LER limitations of the CAR system. The new design exploits “unzipping” polymers that depolymerize upon irradiation such that a single radiochemical event results in breaking many covalent bonds, which provides gain, but the bond breaking is limited to a single chain which limits bias and LER. The key polymer, an aromatizing polyester was successfully prepared by two distinctively different synthetic routes. A cyclic oligomerization side reaction was confirmed by x-ray crystallography and a means to avoid the side reaction was established. A resist formulated from the new polyester blended with m-cresol novolac demonstrates high resolution, high contrast and higher sensitivity than conventional resists under electron beam exposure. The formulation successfully achieves gain without employing a catalyst and it shows promising for the future of this new design for high resolution imaging materials.

Synthesis and characterization of aromatizing polyester

253rd National Meeting (2017)

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