trenches 61 are filled during the course of a gas phase deposition process with the filling material also being deposited above an upper edge of the trenches 61 and forming the process layer 3 the process layer 3 is removed above the substrate surface 10 in the course of a chemical mechanical polishing process on detection of an etching signal which is produced by exposed sections of the etching signal layer 2 the polishing process is ended fig6 b shows the process layer 3 u2032 that has been structured in this way and is recessed into the trenches 61 in comparison to the exemplary embodiment illustrated in fig6 a 6b the exemplary embodiment in fig7 a 7b shows the process layer 3 as a layer stack with the first second and third stack layers 331 332 333 0062 fig8 a 8b shows the etching method according to the invention in conjunction with an isotropic etching process fig8 a shows the substrate 1 with the structured surface 10 the etching signal layer 2 is in the form of a conformal coating on the substrate 1 in the region of the substrate surface 10 the process layer 3 with a planar surface is adjacent to the etching signal layer 2 a structured etching mask 4 is applied to the process layer 3 the process layer 3 is structured in accordance with the structure of the etching mask 4 using an etching process with an isotropic component the.