Effects of Ar+ ion beam interaction with TiN coatings

In this paper TiN films, 2μm thick, deposited on a steel substate by reactive Ti sputtering in a nitrogen atmosphere, have been bombarded by 3 keV Ar+ ions directed normally to the surface. On the bombarded target, the effects of the ion beam interaction with the material as a function of Ar+ ion dose (5.1017-3.1019 ions cm-2) have been investigated by using a scanning electron microscope and a profilometer. The value of the TiN film sputtering coefficient and the depth of the Ar+ ion penetration into the target have been calculated. The value obtained for STiN = 1.02. Slight changes of microhardness of the TiN layers after bombardment are the result of low depth penetration of ions into the target. The decrease in microhardness of about 40% at the highest dose is a result of the decrease of the TiN layer thickness of about 20%. Structural changes are caused by preferential sputtering of some crystal planes and inhomogeneous sputtering at grain boundaries, impurities and micro defects in the layer. (author)