Abstract: A resist utilized to prepare semiconductor elements or the like comprises a copolymer of, for example, 2,3 dibromo-n-propyl methacrylate and methylmethacrylate. The resist is applied onto a substrate to form a copolymer resist layer, the copolymer resist layer is irradiated with ionizing radiations, the irradiated portions of the copolymer resist layer are dissolved to form a positive pattern, the positive pattern is heated in inert atmosphere to cause crosslinking reaction of reactive radicals remaining in the copolymer resist, and then the assembly is etched with a liquid etchant to form an etched pattern on the substrate. Alternatively, the positive pattern and the underlying substrate are treated with plasma or ions to cause a crosslinking reaction of reactive radicals remaining in the copolymer resist to simultaneously etch portions of the substrate not covered by the positive pattern.