A semiconductor device according to the invention includes a first Cu interconnect and a first barrier insulating film. a The first barrier insulating film is provided on the first Cu interconnect, and prevents Cu from being diffused from the first Cu interconnect. In addition, the semiconductor device includes a second Cu interconnect and a second barrier insulating film on the first barrier insulating film. The second barrier insulating film is provided on a first Cu interconnect, and prevents Cu from being diffused from the second Cu interconnect. The first and second barrier insulating films are made of a silicon-based insulating film having a branched alkyl group and a carbon-carbon double bond.