Forming a trenched connecting strip during the production of an integrated deep trench DRAM switching element comprises preparing a deep trench in the substrate, forming an edge on the deep trench, and further processing

摘要

Forming a trenched connecting strip during the production of an integrated deep trench DRAM switching element comprises preparing a deep trench in the substrate; forming an edge on an upper region of the deep trench; filling the deep trench and coating the edge with a silicon layer to form a deep trench capacitor. Next steps involve removing the silicon layer to below the upper surface of the substrate to leave a recess; back-etching an upper region of the edge to leave an edge notch; and selectively etching a deposition layer in the deep trench and filling the notch to form the connecting strip. The edge is made from a thermally grown or deposited oxide. The silicon layer is made from amorphous silicon. The recess has a depth of 50-200 nm. The edge notch is 30-50 nm. The deposition layer is a polysilicon layer having a hemi-spherical grain formation, a SiGe layer, a polysilicon layer and a pseudo-epitaxial silicon layer.