Resist materials design: Base-catalyzed chemical amplification

Abstract

Many chemically amplified resists that function on the basis of acid catalysis of thermolytic reactions have been described as well as systems that function on the basis of free radical chain reactions. But there have been very few reports on the use of base catalysis of chemical transformations in resist materials. We describe here our initial results on base catalyzed chemically amplified deep-UV photoresists. Photogenerated amines were used as catalysts for the decarboxylation of carboxylic acids. Two approaches to building resists around this chemistry were investigated. 1) Decarboxylation of a low molecular weight carboxylic acid led to base induced dissolution inhibition of a phenolic polymer giving negative tone images. 2) A carboxylic acid polymer was synthesized which also is susceptible towards base catalyzed decarboxylation. Wet development of this resist material gives negative tone images. Site specific gas-phase silylation of the carboxylic acid allows the use of this material in a positive tone dry develop process. A 0.5jm linespace pattern obtained by this dry develop process illustrates the potential of base-catalyzed chemical amplification.