Patent ID: 7332789

Claim:
An integrated circuit device comprising: a trench that extends into a substrate; a first dielectric plug disposed in the trench so that an upper surface of the first dielectric plug is located below an upper surface of the substrate, the first dielectric plug comprising a layer of a first dielectric material in contact with a layer of a second dielectric material interposed between the substrate and the layer of the first dielectric material, ends of the layer of the second dielectric material recessed into the trench below the upper surface of the substrate to a level of an upper surface of the layer of the first dielectric material, the ends of the layer of the second dielectric material and the upper surface of the layer of the first dielectric material forming the upper surface of the first dielectric plug, wherein the first dielectric material is a spin-on dielectric and the second dielectric material is a nitride; and a second dielectric plug of a third dielectric material disposed in the trench on the upper surface of the first dielectric plug.