US Patent 7745868 Semiconductor device and method of forming the same

A semiconductor device may include a MOS transistor having source and drain regions in a semiconductor substrate, a first inter-layer insulator having first contact holes that reach the source and drain regions over the MOS transistor. Cell contact plugs in the first contact holes contact with the source and drain regions. A second inter-layer insulator over the first inter-layer insulator and the cell contact plugs has second contact holes that reach the cell contact plugs. Contact plugs each have first and second portions. The first portion is in the second contact hole. The second portion extends over the first second inter-layer insulator. Metal barrier layers cover the upper surfaces of the second portions of the contact plugs. Capacitors each have a bottom electrode layer, a capacitive insulating layer and a top electrode layer. The bottom electrode layers each have a contact portion that contacts with the metal barrier layer.