Manufacturing method of semiconductor device

The purpose of the invention is to prevent from the occurrence of recessing inward and trench in the dual metal damanscene method. For the semiconductor device having the manufacturing process of the cross section structure shown in figure 2(A), one part of the copper film (26) is oxidized to form oxide (43) as shown in figure 2(B) where an etching process is conducted onto silicon nitride and is followed by depositing CFx deposition (44) on top of the oxide (43). However, by using hydrogen plasma to etch the organic insulation film as shown in figure 2(C), the oxide (43) is reduced to form copper. In addition, the CFx deposition is changed into the volatile compound and can be removed.