Preparation of nitride films by Ar+-ion bombardment of metals in nitrogen atmosphere

A preparation of thin nitride films on metal surfaces was presented. The nitrogenation was carried out by bombarding the metals with 8-keV Ar+ ions in nitrogen at 1.0×10−3 Pa. Among the 13 metals examined, the nitrides of nine metals were produced. The approximate thickness of the TiN film was ∼7 nm, which is comparable to the range of the Ar+ ion. The saturated values of the surface N/Me (Me:metal) are different among various metals examined, and are related to the chemical reactivity of the metal with nitrogen. The N/Ti ratio was inversely proportional to the Gibbs energy of nitride formation. These results suggest that the nitride was produced not only through the knock-on collision by the Ar+ ions but also through the thermochemical reaction at the nitrogen–metal interface, which is promoted by the ion bombardment.