Photogenerated base and chemical amplification: A new resist based on catalyzed decarboxylation

Since the concept of chemical amplification in microlithography was first developed in the early 1980`s, a number of new resists based on acid catalyzed thermolysis have been developed. This report describes the first chemically amplified resist operating on the basis of photogenerated base. The concept is demonstrated with poly(2-cyano-2(p-vinylphenyl)butanoic acid) which decarboxylates readily under basic conditions. A resist system consisting of this polymer and an amine photogenerator, bis[((2,6-dinitrobenzyl)oxy)carbonyl]hexan-1,6-diamine, was formulated. The sensitivity of this resist is 1.4 mJ/cm{sup 2} with a contrast ({gamma}) of 13.7. This high sensitivity confirms that chemical amplification is achieved as the photogenerated base is not consumed in the overall decarboxylation process. The mechanistic insights of the decarboxylation reaction in a polymer matrix will also be discussed.