Patent ID: 6514816
Filing Date: 2003-02-04
Classification: H01L

Abstract:
A method of fabricating a self-aligned trench suitable for a substrate, the substrate having a mask layer thereon and two deep trenches therein defined by the mask layer, wherein two internal electrodes of a capacitor are formed in the two deep trenches, the steps of the method comprising:forming two conductive layers to fill the two deep trenches so that top parts of the two conductive layers are higher than the mask layer and a portion of sidewalls of the two conductive layers is exposed, wherein the two conductive layers are electrically connected to the two internal electrodes of the capacitor; forming two spacers on exposed sides of the two conductive layers; forming two doped regions in the substrate next to the two conductive layers, wherein a doping type of the doped regions is different from a doping type of the substrate; removing a portion of the mask layer between the spacers and between the two conductive layers to expose a portion of the substrate between the two conductive layers; removing the spacers between the two conductive layers and a portion of the exposed substrate; removing a portion of the mask layer which portion is originally covered by the removed spacers; removing a portion of the conductive layers and the remaining spacers on the sidewalls of the two conductive layers, and using the remaining portion of the mask layer as a mask to remove a portion of the exposed substrate in order to form a trench, wherein a remaining portion of the conductive layers completely covers a top part of the internal electrodes of the capacitor and a top part of the remaining portion of the conductive layers are lower than that of the substrate covered by the mask layer, and the two doped regions serve as buried source/drains (S/D); and forming a trench isolator in the trench.