Patent ID: 6946344

Claim:
A method for forming a trench capacitor, comprising: providing a semiconductor substrate, wherein a deep trench and a deep trench capacitor are formed therein, the deep trench capacitor having a node dielectric layer and a storage node, the node dielectric layer covering a sidewall and a bottom portion between the deep trench and the storage node of the deep trench capacitor, and the storage node filling the deep trench to a predetermined depth; ion implanting the top portion of the deep trench at a predetermined angle to form an ion doped area on a single sidewall of the semiconductor substrate and the top surface of the deep trench capacitor; forming an oxide layer on the ion doped area; forming a sidewall layer on the sidewall of the deep trench using the oxide layer as a mask, wherein the sidewall layer is isolated from the storage node of the deep trench capacitor; removing the oxide layer; forming a barrier layer on the interior of the deep trench and the sidewall layer; and filling a conducting layer in the deep trench.