Adhesion of NiCu films DC biased plasma-sputter-deposited on MgO (001)

NiCu films about 60 nm thick were deposited on MgO (001) substrates at 230 degreesC by DC plasma-sputtering at 2.7 kV and 8 mA in pure Ar gas using a Ni90Cu10 target. A DC bias voltage U, of 0, - 60, - 110 or - 140 V was applied to the substrate during deposition. The adhesion of the film to the substrate was studied using a scratch test as a function of U,. The application of U, is very effective in increasing the adhesion of the film to the substrate. in conclusion, the adhesion increases with cleaning the substrate surface by sputtering off impurity admolecules during the film initial formation due to the energetic Ar ion particle bombardment.