Prodn. of sub-lithographic etching mask comprises: (a) applying an oxide layer (2) and a Si layer (3) on a semiconductor substrate (1); (b) applying an auxiliary layer (4) on the Si layer (3); (c) structuring the auxiliary layer (4); (d) producing a 1st spacer (7) on the flanks (6) of the structured layer (4); (e) removing the auxiliary layer (4); (f) partially removing the Si layer (3) using the 1st spacer (7) as mask; (g) removing the 1st spacer (7) so that an elevated region of the Si layer (3) remains at this site; (h) applying a further auxiliary layer and structuring to form paths (5) and (8); (i) repeating steps (d) to (g) with a second spacer (9) so that elevated Si layer regions (10) are produced and the Si layer is completely removed using the second spacer as mask; (j) removing the Si layer (3) under spacer (9) so that elevated regions are completely removed; (k) structuring the oxide layer below the Si layer (3) using the regions (10) as mask; (l) utilising the etched oxide layer (2) as etching mask for the structure product.
