Resist mask formation process

Claim 1

A process for forming a resist mask comprising: coating on a substrate a layer of a polymer of a lower alkyl ester of methacrylic acid, wherein the alkyl group contains 1 to 4 carbon atoms, having a molecular weight, M w , of at least about 100,000, which is degradable by high energy radiation of dosage levels above about 1×10 - 6 coulombs per square centimeter, exposing said layer, patternwise, to a scanning electron beam having an energy of 10 to 50 KV with said exposure providing from 3 to 30 microcoulombs per square centimeter of energy to said layer so as to lower the molecular weight of the polymer in the exposed portions, and developing said layer to remove the exposed portion of said layer by immersing said layer in an organic liquid developer, said developer being selected from the group consisting of alkyl acetates and ketones having between 7 and 9 carbon atoms and mixtures thereof, which developer is not a satisfactory developer at ambient temperature, at a temperature of at least about 40° C.