Patent ID: 8058734

Claim:
A semiconductor device, comprising: a semiconductor substrate having an upper surface; a first insulating film formed on the upper surface of the semiconductor substrate, the first insulating film including a first upper surface and a first lower surface and a contact hole extending from the first upper surface to the first lower surface; a lower plug filled in the contact hole and that has a recess defined in an upper portion thereof; a second insulating film formed on the first upper surface, the second insulating film including a second upper surface and a second lower surface and a via hole extending from the second upper surface to the second lower surface; a third insulating film formed on an inner surface of the via hole, the third insulating film extending in a predetermined depth from an upper edge of the via hole so as to reduce a cross sectional area of the via hole, a bottom edge of the third insulating film being located at a higher position than an upper surface of the lower plug; and an upper plug filled in the via hole that has a protrusion formed on a lower portion thereof that conforms to the recess of the lower plug to electrically connect the upper plug and the lower plug.