ADHESION STUDIES OF SPUTTERED ALUMINUM FILMS ON XC-70 STEEL SUBSTRATES - EFFECTS OF THE APPLICATION OF A BIAS VOLTAGE ON THE SUBSTRATE DURING DEPOSITION

The adhesion strength of sputtered aluminium films to XC 70 steel subs trates has been studied using the scratch adhesion test. The influence of the application of a bias voltage on the substrate during depositi on was investigated by means of a mean critical load derived from a We ibull-like statistical analysis. It was found that in the absence of b ias, the interface is rather abrupt, while the interface obtained with the application of a bias voltage is much more diffuse. We can consid er that the widening of the interfacial region offers a better film an chorage on its substrate, requiring a stylus load value clearly excess ively high to produce an adhesion failure.