There is provided a semiconductor device having high reliability, high yield, and such a interconnection structure as short hardly occurs. The semiconductor device comprises a semiconductor substrate, metal conductors formed on a side of a main face of the substrate which metal conductors contain aluminum as main constituent thereof and copper as an additive element, the metal conductors being made to contain such an element as to suppress the precipitation of copper or being made to have such a film adjacent to the metal conductor as to suppress the precipitation of copper.