Method for fabricating a deep trench capacitor for dynamic memory cells

摘要

A method for fabricating a deep trench capacitor for dynamic memory cells in which a trench is etched into the depth of a semiconductor substrate, and wherein the interior of the trench is provided with a doping and a dielectric and is filled with a conductive material as an inner electrode. The inner electrode and the dielectric are etched back within a collar region, and a collar is formed using a collar process comprising a collar oxide deposition and etching back of the collar oxide on the substrate surface and in the trench as far as the inner electrode, after which the inner electrode is completed by further steps of depositing and etching back conductive layers. Prior to the doping a masking layer is applied to the collar region of the trench, and this masking layer is removed again before the collar process. Before the dielectric is applied the surface of the lower regions of the trench outside the collar region a layer of grains of conductive material is applied.