Interface structure and adhesion between a Si substrate after an Ar ion bombardment pretreatment and Ni(100–1500 nm)/Ti(250 nm) double layers prepared in a dc magnetron sputtering apparatus have been investigated.
Two extra layers were generated between the Ti layer and the Si substrate in as-deposited condition. One was an amorphous Si (a-Si) layer(∼ 2 nm) formed on the single crystal Si substrate surface which contains Ar atoms. Another is an amorphous Ti-Si (a-Ti · Si) mixed layer( ∼ 3 nm) on the a-Si layer. A peeling test with an adhesive tape showed that the peeling occurred at the interface between the a-Si and the a-Ti · Si. Ar atoms appeared to be distributed at the interface and the direct contact of the a-Ti · Si layer with the Si substrate seems to be prevented.
After preparing the film and subjecting it to heat treatment at 623 K for 30 min, the adhesion decreased by the accumulation of Ar atoms at the interface. At 723 K for 30 min treatment, however, the adhesion increased probably because of Ar atoms diffusion. It is considered that the Ar atoms incorporated at the interface plays an important role on adhesion of the layer.