A method for providing a high temperature imaging resist layer for use in a multilayer resist system. A relatively thick planarizing resist layer is coated onto a suitable substrate to provide a planarizing resist layer having a planar surface. A relatively thin layer of a solvent soluble polysilsesquioxane polymer resist is applied to the planar surface to form an imaging resist which remains solvent soluble at temperatures up to 250.degree. C. The hydroxyl or alkoxy content of the polysilsesquioxane must be 0.05 weight percent or less in order to prevent cross linking of the polysilsesquioxane. The polysiloxane polymer resist is prepared by hydrolizing and polymerizing trichlorosilanes having the formula RSiCl.sub.3 where R is methyl, phenyl, vinyl, n-butyl, t-butyl, chlorophenyl, or chloromethyl-phenyl. The hydroxyl content of the polysilsesquioxane is reduced to 0.05 weight percent by capping the polymer with monoreactive silanes. The polysiloxane imaging resist is designed for use in high temperature electron beam and ion beam lithography.