Photogenerated Base in Resist and Imaging Materials:  Design of Functional Polymers Susceptible to Base Catalyzed Decarboxylation

A chemically amplified resist material consisting of poly[2-cyano-2-(p-vinylphenyl) butanoic acid] and bis[[(2-nitrobenzyl)oxy]carbonyl]hexane-1,6-diamine has been designed and tested in negative and positive tone imaging. The resist operates on the principle of base-catalyzed decarboxylation. Amine generated by exposure to UV radiation catalyzes the thermal loss of carbon dioxide from the polymer side chain thereby changing the solubility of the resist film in aqueous base developer. Image reversal is accomplished by in situ silylation of the exposed and thermolyzed film followed by dry development using an oxygen plasma. The resist shows high sensitivity to deep UV irradiation, ca. 10 mJ/cm2, while image contrast is excellent.