Patent ID: 7125766

Claim:
A method of forming a capacitor for a semiconductor device, the method comprising: forming an insulation layer on a substrate surface, the substrate having a contact plug formed thereon; forming a silicon germanium layer on the insulation layer; forming an oxide layer on the silicon germanium layer; anisotropically etching the oxide layer and the silicon germanium layer to form an opening, the opening having an upper portion through the oxide layer and a lower portion through the silicon germanium layer, and being formed to expose the contact plug; isotropically etching the lower portion of the opening to form a recessed opening in the silicon germanium layer, the recessed opening having a width greater than a width associated with at least some portion of the upper portion of the opening; forming a storage electrode on the contact plug in conformity with sidewalls of the opening; and, forming a dielectric layer and a plate electrode covering the storage electrode.