Effect of Nitrogen Flow Ratios on the Microstructure and Properties of Ta–Al–N Thin Films by Reactive Cosputtering

Abstract

Quasi-amorphous Ta–Al films were obtained at the atomic ratio of . The properties of quasi-amorphous films may be different from the polycrystalline ones. In this paper, the Ta–Al–N thin films were prepared by the nitridation of quasi-amorphous Ta–Al alloys using reactive magnetron cosputtering at various nitrogen flow ratios . The mechanical and electrical properties of the Ta–Al–N thin films were related to the quasi-amorphous and polycrystalline microstructure. X-ray diffraction evidenced that the quasi-amorphous Ta–Al–N films were formed at 2–7.5 while the polycrystalline ones were obtained at 10–20 . The hardness of Ta–Al–N films was between 7.1 and by means of nanoindentation. A maximum hardness was found at 7.5 due to the composite quasi-amorphous microstructure with nanocrystalline grains embedded in an amorphous matrix to enhance the mechanical properties. The resistivity of the polycrystalline Ta–Al–N films was much higher than that of the quasi-amorphous Ta–Al–N. The high resistivity of Ta–Al–N at 10–20 was about in the nonconducting range.