To suppress coagulation of Cu by forming interconnections having conductor films, which are composed solely or mainly of copper on titanium films containing prescribed contents of nitrogen on their surfaces.

A first barrier film 9a, a second barrier film 9b, and a first conductor film 10a are sequentially deposited through sputtering method from the bottom as the underlying layers for a plated Cu film. The film 9a is comprised of a TiN film containing 30 at.% or higher of nitrogen, and the film 9b is comprised of a Ti film containing about 10-30 at.% of nitrogen. Furthermore, the film 10a is comprised of a Cu film. A second conductor film 10b is formed by the same method as that for the film 10a. Then, a first metal film 12a and a second metal film 12b are deposited on the films 10a and 10b, respectively. With this arrangement, the coagulation of Cu can be suppressed.