Production of deep trench capacitor used for DRAM comprises forming structured mask layer on the substrate, forming deep trench in the substrate using the mask layer as mask, forming doped region in the substrate, and further processing

摘要

Production of a deep trench capacitor comprises preparing a substrate (200); forming a structured mask layer (202) on the substrate; forming a deep trench in the substrate using the mask layer as a mask; forming a doped region (212) in the substrate to surround a lower section of the trench; forming a capacitor dielectric layer on an inner surface of the trench; forming a first conducting layer which completely fills the trench; removing a part of the first conducting layer; forming an edge oxide layer (220) on the substrate; forming an edge covering layer on the edge oxide layer; removing a part of the edge covering layer; removing the edge oxide layer on an upper surface of the mask layer; removing the edge covering layer on the side walls of the trench; and subsequently forming a second conducting layer and a third conducting layer to completely fill the trench. Preferred Features: The material forming the edge covering layer is made from silicon nitride, polysilicon, silicon or silicon oxynitride. The edge covering layer is removed by anisotropic etching. The conducting layers are made from doped polysilicon.