Patent ID: 7163858

Claim:
A method for fabricating a deep trench capacitor, the method comprising: performing a patterning process to form a plurality of deep trenches in the substrate using a patterned mask disposed above a substrate; forming a bottom electrode in the substrate surrounding a bottom of each deep trench; forming sequentially a capacitor dielectric layer and a first conductive layer at the bottom of each deep trench; forming a collar oxide layer on a sidewall of each deep trench exposed by the first conductive layer; filling each deep trench with a second conductive layer, wherein the second conductive layer at least fully fills each deep trench; removing the patterned mask layer and a portion of the substrate between two neighboring deep trenches and removing portions of the second conductive layer and the collar oxide layer in the two deep trenches to form a first opening, wherein the first opening is formed at a region for forming a predetermined isolation structure between the two neighboring deep trenches, and a depth of the first opening is greater than a depth of the predetermined isolation structure; and filling the first opening with an isolation layer.