Capacitor having tapered cylindrical storage node and method for manufacturing the same

A method for manufacturing a capacitor, comprising the steps of:

• forming a buffer oxide layer, an etching stop layer, and a mold insulation layer over a semiconductor substrate provided with a storage node contact plug;
• etching the mold insulation layer and the etching stop layer to form a first hole in an upper portion of the storage node contact plug;
• depositing a tapering layer over the mold insulation layer including inside the first hole, wherein the thickness of the tapering layer at an upper end portion is thicker that than the thickness of the tapering layer at a lower end portion;
• etching back the tapering layer and the buffer oxide layer so that a second hole for exposing the storage node contact plug is formed, wherein the tapering layer is remained only at an upper end portion of the second hole;
• forming a metal layer for a storage node on the surface of the second hole including the remaining tapering layer at an upper end portion of the second hole;
• removing the mold insulation layer and the remaining tapering layer to form a cylindrical storage node, wherein an upper end portion of the cylindrical storage node has a tapered shape;
• and
• forming a dielectric layer and a plate node over the storage node.

A method for manufacturing a capacitor, comprising the steps of:

• forming a buffer oxide layer, an etching stop layer, and a mold insulation layer over a semiconductor substrate provided with a storage node contact plug;
• etching the mold insulation layer, the etching stop layer, and the buffer oxide layer to form a hole for exposing the storage node contact plug;
• depositing a tapering layer over the mold insulation layer including inside the hole, wherein the thickness of the tapering layer at an upper end portion is thicker that than the thickness of the tapering layer at a lower end portion;
• etching back the tapering layer to expose the storage node contact plug, wherein the tapering layer is remained only at an upper end portion of the hole;
• forming a metal layer for a storage node on the surface of the hole including the remaining tapering layer at an upper end portion of the hole;
• removing the mold insulation layer and the remaining tapering layer to form a cylindrical storage node, wherein an upper end portion of the cylindrical storage node has a tapered shape;
• and
• forming a dielectric layer and a plate node over the storage node.