Production of an insulating collar in a trench capacitor comprises forming a trench in the substrate, forming an insulating layer in the trench, filling with filler material

摘要

Production of an insulating collar in a trench capacitor comprises: (a) preparing a semiconductor substrate (5), forming a trench (10) in the substrate; (b) forming an insulating layer (35) in the trench to form an insulating collar (75); (c) filling a lower region (50) of the trench with a sacrificial filler material (40) so that an upper region (45) of the trench remains free from the filler material; (d) forming a structured layer on the insulating layer and on the filler material; (e) forming an opening (60) in the structured layer, removing the filler material; and (f) removing the insulating layer from the lower region by etching the insulating layer selectively to the structured layer. Preferred Features: The structured layer and the filler material are made of silicon nitride, polysilicon, amorphous silicon or photolacquer.