Apparatus and process of fabricating a trench capacitor

Abstract

A process of fabricating a deep trench capacitor includes the steps of: depositing a nitride masking layer over a substrate; removing portions of the nitride masking layer and substrate to form an exposed deep trench having sidewalls and a bottom surface; forming an oxide fill plug to fill a bottom portion of the trench; removing the oxide fill plug from the trench; doping a region of the substrate enveloping the bottom portion of the trench; depositing a spacer insulating layer over the sidewalls and bottom surface of the trench; removing a portion of the spacer insulating layer to expose a central portion of the bottom surface of the trench; depositing a conducting layer over the spacer insulating layer, and the exposed central portion of the bottom surface, the conducting layer and the doped region of the substrate being in electrical contact and forming a first plate of the capacitor; removing a portion of the conducting layer; removing the spacer insulating layer to expose outer walls of the conducting layer; removing the protection layer; forming a dielectric layer over the sidewalls of the trench and over the top surface, inner walls, and outer walls of the conducting layer; and depositing a conducting plug over the dielectric layer and filling the trench, the conducting plug forming at least a portion of a second plate of the capacitor.