Semiconductor device having a plurality of conductive layers interconnected via a tungsten plug

Claim 1

A semiconductor device comprising a semiconductor substrate, an insulating layer formed on said semiconductor substrate, a plurality of conductive lead circuit layers including a first conductive lead circuit layer and a second conductive lead circuit layer, said first conductive lead circuit layer being formed over the semiconductor substrate, said second conductive lead circuit layer being formed over an intermediate insulating layer formed over said first conductive lead circuit layer, a plurality of holes formed in the intermediate insulating layer and extending between said first and second conductive layers, each of said holes having a width which is larger than a width of a connection portion of said first conductive lead circuit layer exposed in said hole, said hole having a depth that exposes both a top face and an upper side face of the connection portion of said first conductive lead circuit layer, conductive plugs in the holes for making electrical connections between the connection portions of said first conductive lead circuit layer and said second conductive lead circuit layer exposed in said hole, a cross section of said plugs being smaller than cross sections of said holes in at least one dimension to leave at least one space between a plug and an inner wall of said hole, each of said conductive plugs having a width which is larger than the width of said connection portion of the first conductive lead circuit layer and being formed over both the top face and at least an upper side face of said connection portions of the first conductive lead circuit layer, and an insulating material filling said space between said conductive plugs and the inner walls of said holes.