MICROSTRUCTURE AND COMPOSITION OF TITANIUM NITRIDE FORMED BY ION-BEAM-ENHANCED NITROGEN SORPTION OF EVAPORATED TITANIUM UNDER ARGON ION IRRADIATION

Deposition of titanium nitride by ion beam-assisted evaporation (IBAD) is possible by two methods. One is evaporation of the metal under bom bardment with nitrogen ions at a low gas pressure. The metal is conver ted to the nitride by implantation of the ions. The other method is ev aporation of the metal in an atmosphere of nitrogen gas under bombardm ent with rare gas ions. The metal reacts with gas molecules from the a mbient atmosphere. The features of the obtained TiN films strongly dep end on the process mode. In the present study, TiN films prepared by g as sorption under argon ion bombardment are dealt with. The ion energi es were in the medium-to-high energy regime of IBAD (> 10 keV). Owing to the high mass of the bombarding species and a comparatively high en ergy, the TiN films are subject to heavy radiation damaging during dep osition. This influences the microstructure and composition of the fil ms. Argon ion irradiation leads to a reduction in contamination by res idual gas. The oxygen content is reduced from 10-20 at.% down to below 5 at.%. On the other hand, argon is incorporated up to 6 at.%. The cr ystal orientation changes from [111] to [100], and a fiber texture dev elops. The grain size increases from approximate to 10 nm without ion bombardment up to 300 nm at high ion current densities. Without ion bo mbardment and at very low irradiation intensities, the material develo ps a fine-grained structure. With increasing ion irradiation intensity , the grains grow as large columns. (C) 1998 Elsevier Science S.A. All rights reserved.