Surface cleaning method for elimination of Cu-oxide layer formed on Cu film

We investigated the effects of surface cleaning to eliminate the surface native oxide on Cu film. The Cu seed layer was deposited on Ti/p-Si (100) by sputter deposition. NH₄OH and H₂SO₄ solutions after TS-40A pretreatment were used to remove the Cu-oxide, and then the changed surface of Cu film was estimated by AFM, SEM, and XPS. By H₂SO₄ treatment after TS-40A pretreatment, the Cu-oxides on surface of Cu seed film [including CuO, Cu(OH)₂, and CuCO₃ contaminants] were eliminated uniformly. However, by NH₄OH treatment after TS-40A pretreatment numerous large and small etch pits formed and the RMS roughness of Cu film surface was larger. Consequently, we found that H₂SO₄ cleaning after TS-40A pretreatment is very effective at Cu-oxide removal.