Solid-state electron beam chemistry of mixtures of diazoketones in phenolic resins: AZ resists

Abstract

Equimolar mixtures of a 2-diazo-1-naphthaquinone and a phenolic resin are exposed to a 25-kV electron beam and UV light. The mechanism for the photochemistry is explained on the basis of the well-known Wolff rearrangement. The electron beam exposure, however, does not appear to proceed via the Wolff rearrangement but instead invokes reactions of a carbene with the phenolic resin. The carbene, formed by loss of N2 from the diazoketone, forms chemical products with the resin which are soluble in base. In essence, this explains the functioning of a large class of electron beam resists consisting of diazoketone/resin mixtures. Electron beam exposures are also performed on mixtures of 2-diazo-1-naphthaquinone in m-cresol or in benzene; the results of these experiments suggest that a major product of the electron beam induced chemistry is a substituted naphthol. © 1988 American Chemical Society.