A process for subsequent surface modification of finely structured structures formed from hard inorganic materials, and the structures obtainable by this process as such. The structure has, in at least one spatial direction, a material thickness M of not more than 1000 nm and as an overall structure having, in at least one spatial direction, a measurement which is at least 5 times the material thickness M. The process includes treating the structures with an organic liquid under supercritical conditions.