Patent ID: 6852590

Claim:
A method for fabricating a deep trench capacitor, comprising: providing a substrate, having a deep trench formed therein, a doped region formed at a bottom of the deep trench, a capacitor dielectric layer formed over a surface of the bottom of the deep trench, and a first conductive layer formed over the capacitor dielectric layer; forming a collar oxide layer on sidewalls of the deep trench that are not covered by the first conductive layer; forming a material layer within the deep trench, covering the first conductive layer, and exposing a portion of the collar oxide layer; removing the exposed portion of the collar oxide layer for exposing the substrate at sidewalls of the top of the deep trench; removing the material layer; and forming a second conductive layer, covering the first conductive layer and the collar oxide layer, the second conductive layer contacting the substrate at the sidewalls of the top of the deep trench.