Patent ID: 6200904
Filing Date: 2001-03-13
Classification: H01L

Abstract:
A method of forming a contact hole of a dynamic random access memory (DRAM), the dynamic random access memory being formed in a semiconductor wafer and comprising:a substrate;a first dielectric layer positioned on the substrate;two bit lines positioned on the first dielectric layer each having a rectangular-shaped cross section;a second dielectric layer positioned on the first dielectric layer and two bit lines; anda photo-resist layer positioned on the second dielectric layer, the photo-resist layer comprising an opening positioned above the space between the two bit lines and partially overlapping the two bit lines;wherein the method of forming the contact hole comprises:performing a first anisotropic etching process to vertically remove the second dielectric layer under the opening down to the top ends of two bit lines, and then continuing the process along the side walls of the two bit lines to vertically remove the second dielectric layer positioned between the two bit lines and the first dielectric layer in a downward direction to grossly form the contact hole while retaining portosns of the first dielectric layer under the contact hole on the substrate;performing a second anisotropic etching process to vertically remove the portions of the two bit lines under the opening down to the first dielectric layer;removing the photo-resist layer in its entirety;performing a thermal oxidation to form an insulating layer on the side walls of the two bit lines in the contact hole;forming a passivation layer on the second dielectric layer and the surface of the contact hole to protect the insulating layer on the side wall of the two bit lines in the contact hole; andperforming a third etching process on the surface of the second dielectric layer and contact hole to remove the passivation layer and the remaining first dielectric layer from the bottom of the contact hole down to the substrate to complete the contact hole.