Method for increasing tolerance of contact extension alignment in cob dram

Abstract

A method for increasing tolerance of contact extension alignment in a capacitor over a bit line of a dynamic random access memory is disclosed. Firstly, a substrate having a gate, a bit line and a source/drain region is provided and a insulating layer is formed on the substrate. Then, a dielectric layer is deposited on the insulating layer. Moreover, a contact hole is formed by defining and etching the dielectric layer and the insulating layer to expose a portion of the source/drain region. Furthermore, a conductive layer is deposited on the dielectric layer and the contact hole, wherein the etching selectivity ratio of the conductive layer is near the etching selectivity ratio of the dielectric layer. Finally, an electrode of the capacitor is formed by defining and etching the conductive layer, whereby the dielectric layer protects the portion of the electrode that is beneath the dielectric layer from being etched when misalignment occurs.