Patent ID: 6902982
Filing Date: 2005-06-07
Classification: H01L

Abstract:
1. A trench capacitor process for preventing parasitic leakage, comprising the steps of: providing a substrate with a trench formed therein, wherein the trench has a buried plate formed adjacent to the lower portion thereof; forming a dielectric layer and a first conductive layer in the lower portion of the trench, wherein the buried plate and the first conductive layer are separated by the dielectric layer; conformably depositing a layer of doping material on the substrate, the sidewalls in the upper portion of the trench and the dielectric layer and the first conductive layer in the lower portion of the trench; removing the portion of the doping material on the substrate and the dielectric layer and the first conductive layer in the lower portion of the trench to leave a doping layer on sidewalls of the trench; forming a protective plug in the trench to expose a portion of the doping layer; removing the portion of the doping layer exposed by the protective plug; removing the protective plug to form a doping layer on portions of each sidewall of the trench above the dielectric layer and the first conductive layer; forming a cap layer on each exposed sidewall and each doping layer; performing an annealing process on each doping layer to form a dopant region in the adjacent substrate, wherein each dopant region blocks leakage current resulting from a parasitic transistor adjacent to the trench and has a first distance from the surface of the substrate; forming a second conductive layer in the trench to expose portions of the cap layers, wherein the second conductive layer contacts the first conductive layer and has substantially the same height with respect to the dopant regions; removing portions of the cap layers exposed by the second conductive layer to reveal portions of the sidewalls in the upper portion of the trench; and forming a third conductive layer on the second conductive layer to fill the trench, wherein the third conductive layer directly contacts the exposed sidewalls in the upper portions of the trench.