Composition and structure of titanium nitride films prepared by ion beam enhanced deposition

Abstract

Titanium nitride films have been prepared by simultaneous vacuum deposition of titanium and nitrogen ion beams with ion energy of 40 keV. The atomic arrival ratio of implanted ions to deposited atoms was varied from 0 to 0.5. The film composition and structure were analyzed by RBS, AES, TEM and XRD. The results show that nitrogen ion bombardment can clearly reduce the oxygen concentration in the film. The component ratio (N/Ti) in films prepared at low temperature was greater than that in the films prepared at high temperature. At the same atomic arrival ratio, the component ratio (N/Ti) in the films decreased with increasing titanium deposition rate. These results are considered to occur since the film composition is strongly affected by the adsorption of nitrogen, which depends sensitively on the substrate temperature, titanium deposition rate and pressure of nitrogen gas in the target chamber. The films were mainly TiN polycrystals, whereas only amorphous structures have been observed in films prepared under the same condition but without nitrogen ion bombardment. The preferred crystalline orientation of the film changed from 〈111〉 to 〈200〉 with an increase of the atomic arrival ratio (N/Ti). Such a variation is due to the difference in energy deposition on each titanium atom from the nitrogen ion beam during the ion beam enhanced deposition (IBED) process.