Method of forming DRAM capacitors with a native oxide etch-stop

Claim 1

A process for fabricating a DRAM capacitor, comprising: providing a substrate having at least one transistor formed thereon; forming an insulation layer on the surface of the substrate, the insulation layer having a contact opening exposing a source/drain region of the transistor; forming a bottom electrode that extends into the contact opening, said forming a bottom electrode comprising: forming a first electrically conductive layer covering the insulation layer and filling the contact opening, with the first electrically conductive layer contacting the exposed source/drain region; naturally forming a native oxide layer on the first electrically conductive layer; forming a second electrically conductive layer on the native oxide layer, the second electrically conductive layer being patterned to form a recess substantially positioned above the location of the contact opening formed in the insulation layer; forming a layer of hemispherical-grain polysilicon over the surface of the second electrically conductive layer and the surface of the recess, the layer of hemispherical-grain polysilicon electrically coupling the second electrically conductive layer to the first electrically conductive layer, the hemispherical-grain polysilicon layer, the second electrically conductive layer, the native oxide layer and the first electrically conductive layer being subsequently patterned to form the bottom electrode; forming a dielectric material layer on the bottom electrode; and forming a top electrode on the dielectric material layer.