a semiconductor device includes : a first insulation film formed over a semiconductor substrate ; and a plurality of first interconnects selectively formed in the first insulation film . a plurality of gaps are formed in part of the first insulation film located between adjacent ones of the first interconnects so that each of the gaps has a cylindrical shape extending vertically to a principal surface of the semiconductor substrate . a cap film is formed of metal or a material containing metal in upper part of each of the first interconnects .