Electro:lithographic process for prodn. of resist masks - by irradiating a polymeric resist layer with ionising radiation grafting polymerisable monomer and heat treating to degrade polymer chains

摘要

Parent patent 3.5.77-FR-013344 describes the prodn. of polymeric resist masks by an electrolithographic process in which the polymeric resist layer (e.g. of epoxy resin or thiirane resin (negative working) or PMMA or polybutene-1 (positive working)) are exposed to ionising radiation such as electron beam or X-rays to form free radicals in the irradiated parts, followed by grafting of a monomer onto the original polymer to modify its chemical structure and thus its solubility, so as to render the irradiated portions differentially (in) soluble in particular solvents w.r.t. the original polymer. The improvement comprises heat treating the material after the grafting stage to cause degradation of the graft polymer areas so as to augment the solubility of these in a solvent developer for the mask. Process is esp. useful for the prodn. of high resolution resist masks used in the prodn. of microelectronic devices.