Thermal stability of amorphous Ti 3Si 1O 8 thin films

Abstract

Films (220 nm-thick) deposited by reactive rf sputtering from a Ti 3Si target with an argon/oxygen gas mixture were annealed for 30 min in vacuum at temperatures between 400 and 900°C. The films were characterized by 2 MeV He 2+ backscattering spectrometry and X-ray diffraction to monitor thermally induced changes. As-deposited, the films are X-ray-amorphous. First signs of crystallization appear at 600°C. Their composition remains constant and uniform throughout that temperature range, except for the loss of argon that is initially present in the film at a concentration of about 1 at.% and that fully escapes within 5 min at 650°C. Films without silicon obtained from a pure titanium target by reactive rf sputtering with oxygen and of a composition of Ti 1O 2 are also X-ray-amorphous but crystallize much more readily. The significance of these results is discussed relative to other ternary films of analogous compositions that also tend to form highly stable amorphous or near-amorphous phases (‘mictamict’ alloys).