A positive-type resist material for forming resist patterns having submicron geometries on a substrate, the resist material comprising a copolymer of a first monomer of silicon containing methacrylic ester and a second monomer of either acrylic ester or acrylonitrile, the alpha-position of the second monomer being substituted by an electron attracting group. The first monomer has a high resistance to an oxygen plasma and the second monomer has a high sensitivity to e-beam/X-ray irradiation. As the electron attracting group, a trifluoromethyl group, a halogen group, a cyano group and a CH.sub.2 CO.sub.2 R group are used. The embodied first monomers are trimethylsilylmethyl methacrylate and (diphenylmethylsilyl)methyl methacrylate, and the embodied second monomers are .alpha.-trifluoromethyl (2,2,2-trifluoroethyl) acrylate and .alpha.-chloroacrylonitrile.