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

Abstract

A process of fabricating a bottom electrode for the storage capacitors of DRAM is disclosed. The process includes first forming an insulation layer on the surface of the device substrate, with the insulation layer patterned to form a contact opening that exposes a source/drain region of the memory cell transistor. A first conductive layer then covers the insulation layer and fills into the contact opening, with the first conductive layer contacting the exposed source/drain region. A native oxide layer is then formed on the surface of the first conductive layer. A second electrically conductive layer is then formed and patterned to form a recess substantially above the location of the contact opening in the insulation layer. A layer of HSG—Si then covers the surface of the second conductive layer and the surface of the recess, and the HSG—Si layer and the second conductive layer are patterned to form the bottom electrode of the capacitor. The recess and its covering HSG—Si layer increase the effective surface area of the bottom electrode of the capacitor.