Negative chemical amplification resist systems based on polyhydroxystyrenes and N-substituted imides or aldehydes

Aqueous base developable negative deep UV resist systems composed of phenolic resins, monofunctional latent olectrophiles, and a sulfonium salt photochemical acid generator are described. This study was carried out to see whether attachment of a bulky substituent onto the phenolic group via C- or O-alkylation reduces the dissolution rate of the phenolic resin in aqueous base to provide negative images even when no crosslinking is involved in the mechanism. The latent electrophiles selected are N-hydroxymethyl and N-aceotxymethylimides as well as high-boiling aldehydes. Our matrix resins are para-, meta-, and ortho-isomers of polyvinylphenol and copolymers of p-hydroxystyrene.