Patent ID: 7109091

Claim:
A method for processing a substrate to form a structure using a lithographic mask exposure, which comprises the steps of: providing the substrate; etching two trenches disposed at a distance from one another, the distance corresponding to an optical resolution limit of the lithographic mask exposure; filling the trenches with a trench filling resulting in filled trenches, wherein filling the trenches includes forming word lines in the two trenches; back-etching a material other than a material of the trench filling in an interspace between the filled trenches at a level of the trench filling resulting in a depression; producing spacers in the depression on opposite sidewalls of the depression, the spacers being at a distance from one another which is less than the optical resolution limit for the lithographic mask exposure; and etching in a region of the depression for forming an insulating trench disposed between the spacers, a width of the insulating trench being less than the optical resolution limit for the lithographic mask exposure.