US Patent 7358613 Semiconductor device and method of manufacturing the same

A semiconductor device includes a plurality of wirings each wiring including a metal wiring layer, a first barrier metal layer disposed on the metal wiring layer, a second barrier metal layer disposed below the metal wiring layer, a first insulating layer disposed below the second barrier metal layer, and a second insulating layer covering the wirings so that a void is defined between the wirings. The void has a larger sectional area than the metal wiring layer and includes an upper portion located between the upper surface and the bottom surface of the first barrier metal layer. The void includes a bottom portion located between the upper surface and the bottom surface of the second barrier metal layer.