Patent ID: 7749834

Claim:
A method of fabricating a contact plug of a semiconductor device, the method comprising: forming a lower dielectric layer on a semiconductor substrate; forming a bit line landing pad and a storage landing pad that penetrate the lower dielectric layer to physically contact the semiconductor substrate; covering the lower dielectric layer, the bit line landing pad, and the storage landing pad with a middle dielectric layer; forming an upper dielectric layer on the middle dielectric layer; partially removing the upper dielectric layer, the middle dielectric layer, and the lower dielectric layer to form a buried contact opening, the buried contact opening exposing a portion of the lower dielectric layer, a portion of the storage landing pad, and a portion of the bit line landing pad; forming a buried contact spacer on a sidewall exposed by the buried contact opening; and filling the buried contact opening with a buried contact plug that physically contacts the storage landing pad, a top surface of the buried contact plug larger than a surface of the buried contact plug that is in contact with the storage landing pad, the top surface of the buried contact plug eccentric to the storage landing pad when seen in a plan view, wherein a bottom of the buried contact opening is lower than a top surface of the storage landing pad.