A photoresist system that is easily structurable and, in particular, is suitable for the deep ultraviolet range is provided. An increased etching resistance to a halogen-containing plasma is produced in a lithographically generated photoresist structure by treatment with a reactant. The reactant comprises predominantly aromatic structures and includes reactive groups that are suitable for chemical reaction with further reactable groups of the photoresist. In an embodiment, the photoresist includes anhydride or epoxy groups that are suitable for structuring with deep ultraviolet light.