Patent ID: 7074689

Claim:
A method for fabricating a trench capacitor having an insulation collar in a substrate, which is electrically connected to the substrate on one side via a buried contact, in particular for a semiconductor memory cell having a planar select transistor which is provided in the substrate and is connected via the buried contact, comprising the steps of: (a) providing a trench in the substrate using a hard mask with a corresponding mask opening; (b) providing a capacitor dielectric in the lower and middle regions of the trench, the insulation collar in the middle and upper regions of the trench and an electrically conductive filling at least up to the top side of the insulation collar; (c) filling completely the trench with a filling material; (d) carrying out an STI trench production process; (e) removing the filling material and lowering the electrically conductive filling to below the top side of the insulation collar; (f) forming an insulation region on one side with respect to the substrate above the insulation collar; (g) uncovering a connection region on the other side with respect to the substrate above the insulation collar; and (h) forming the buried contact by depositing and etching back a C filling.