PURPOSE: To form fine copper wirings by embedding a copper film in a groove formed in an interlayer insulating film and etching back it.

CONSTITUTION: A groove is formed on an SiO2 film 2 formed on a silicon substrate 1, and a copper film 4 is so deposited as to embed the groove. Then, chlorine plasma is formed in an etching chamber of a dry etching unit, the film 4 previously deposited in the plasma is exposed to react the film 4 with a copper chloride film 5 to a surface of the film 2. Then, the substrate 1 is transferred in a vacuum to an ashing chamber without exposing the reacted film 5 with the atmosphere, and heat treated. Then, the substrate 1 is again transferred to the etching chamber to etch back the film 5 by using a plasma by O2 gas or rare gas in the etching chamber, thereby forming copper wirings 6.