An interconnect is provided in a first insulating layer and the upper surface of the interconnect is higher than the upper surface of the first insulating layer. An air gap is disposed between the interconnect and the first insulating layer. A second insulating layer is formed at least over the first insulating layer and the air gap. The second insulating layer does not cover the interconnect. An etching stopper film is formed at least over the second insulating layer. The etching stopper film is formed over the second insulating layer and the interconnect. A third insulating layer is formed over the etching stopper film. A via is provided in the third insulating layer so as to be connected to the interconnect.