Azide-phenolic resin photoresists for deep UV lithography

A photosensitive composition, consisting of an aromatic azide compound (3,3´-diazidodiphenyl sulfone) and a phenolic resin (poly(p-vinylphenol)), called MRS-1, has been prepared and evaluated as a negative deep UV resist for high resolution lithography. Solubility of MRS-1 in an aqueous alkaline developer decreases upon exposure to deep UV radiation. The alkaline developer removes the unexposed areas of MRS-1 by an etching-type development process. No swelling-induced pattern deformation occurs, and images of submicrometer resolution are obtained. The resist is approximately two orders of magnitude more sensitive than PMMA(polymethyl methacrylate). The exposure time of 5 s is sufficient for deep UV contact printing using a 500-W Xe-Hg lamp. The resistance to dry etching of MRS-1 is comparable to that of conventional positive photoresists based on phenolic resin.