Patent attributes
A first interlayer insulating film made of insulting material is formed over an underlying substrate. A via hole is formed through the first interlayer insulating film. A conductive plug made of copper or alloy mainly consisting of copper is filled in the via hole. A second interlayer insulating film made of insulating material is formed over the first interlayer insulating film. A wiring groove is formed in the second interlayer insulating film, passing over the conductive plug and exposing the upper surface of the conductive plug. A wiring made of copper or alloy mainly consisting of copper is filled in the wiring groove. The total atom concentration of carbon, oxygen, nitrogen, sulfur and chlorine in the conductive plug is lower than the total atom concentration of carbon, oxygen, nitrogen, sulfur and chlorine in the wiring.
