Patent ID: 7320912

Claim:
A method for forming a trench capacitor in a substrate, the method comprising: removing a portion of the substrate to form a trench within the substrate; forming at least one buried isolation layer within the substrate, the buried isolation layer intersecting with the trench and having at least one gap providing body contact between a first substrate area above the buried isolation layer and a second substrate area below the buried isolation layer, the step of forming the at least one buried isolation layer within the substrate further including: a) forming at least a first epitaxial layer over the substrate; b) forming at least a second epitaxial layer over the first epitaxial layer; c) defining a body contact area by removing a portion of the first epitaxial layer and the second epitaxial layer; d) forming a third epitaxial layer at least in the body contact area; e) removing the first epitaxial layer; and f) forming the buried isolation layer in or near a space provided by removing the first epitaxial layer, the buried isolation layer being a dielectric layer formed by an oxidation process; forming in the substrate a first electrode of the trench capacitor at least in areas surrounding a lower portion of the trench; forming a dielectric layer of the trench capacitor, the dielectric layer covering a surface of the trench at least for the portion below the buried isolation layer; and forming a second electrode of the trench capacitor in the trench.