Patent ID: 8318576

Claim:
A method for fabricating a capacitor, comprising: providing a semiconductor substrate structure having a top surface; forming a trench opening in the semiconductor substrate structure by selectively removing a portion of the semiconductor substrate structure in a first region to define bottom and sidewall surfaces where the bottom surface exposes a semiconductor region in the semiconductor substrate structure which forms a bottom capacitor plate; forming a first dielectric layer on the bottom and sidewall surfaces in the trench opening; anisotropically etching the first dielectric layer in the trench opening to remove the first dielectric layer from the bottom of the trench opening while retaining a sidewall surface layer on the sidewall surface of the trench opening; forming a capacitor dielectric layer on the bottom of the trench opening; forming a recessed conductive top capacitor plate layer on the capacitor dielectric layer in the trench opening, the recessed conductive top capacitor plate layer having a top surface which is below the top surface of the semiconductor substrate structure; and forming a dielectric layer in the trench opening to cover the recessed conductive top capacitor plate layer, the dielectric layer having a bottom surface which is below the top surface of the semiconductor substrate structure.