Patent ID: 8785999

Claim:
A semiconductor device comprising: a first interlayer insulating film, the first interlayer insulating film including a plug interlayer insulating film, and a bit-line interlayer insulating film provided on said plug interlayer insulating film, a plurality of bit-lines being formed between said plug interlayer insulating film and said bit-line interlayer insulating film, the plurality of bit-lines being covered with a bit-line insulating film disposed between the bit-line interlayer insulating film and the plug interlayer insulating film; a second interlayer insulating film provided above the first interlayer insulating film; a first conductive member provided lower than said first interlayer insulating film; a contact plug comprising a single piece of conductor that includes a small-diameter part, and a large-diameter part arranged over said small-diameter part, an outer diameter of said large-diameter part being larger than an outer diameter of said small-diameter part, said contact plug penetrating through said first interlayer insulating film, and being electrically connected to said first conductive member, said large-diameter part of said contact plug having a top surface with a dented portion toward a bottom of said contact plug, the contact plug being arranged between adjacent bit-lines, at least part of the contact plug being located over a top surface of the bit-line insulating film over the bit-lines; and a second conductive member that is provided on said first interlayer insulating film, and is electrically connected to said contact plug within said dented portion of said large-diameter part of said contact plug, the second conductive member having an outer diameter of a topmost edge of said second conductive member larger than an outer diameter of a bottom of said second conductive member, the second conductive member having side walls and the bottom extending therebetween, the side walls continuously narrowing and extending through the second interlayer insulating film to the first interlayer insulating film within the dented portion of the large-diameter part of the contact plug, wherein the outer diameter of said large-diameter part is larger than the outer diameter of the bottom of said second conductive member, and the outer diameter of the bottom of the second conductive member is larger than a diameter of the contact plug between adjacent bit-lines.