Investigation of the processes of the formation of a nonequilibrium phase-structural state in FeTiB films obtained by magnetron sputtering

Abstract

The main trends of modern developing magnetic microelectronics are miniaturization and speed, while ensuring efficient operation in the MHz and GHz frequency ranges of magnetic fields. Developing new magnetic materials featured by properties that ensure the implementation of these trends is the key fundamental and applied problem of materials science. In this regard, Fe-Me-X nanocrystalline soft magnetic alloys (Me is one of the metals from Group IVb of the Periodic Table, X is one of the N, C, O, B light elements) obtained in the form of films are of interest. As shown earlier by the authors of this article on Fe-Zr-N films, such films featuring by the Fe/MeX two-phase structure can provide a combination of high saturation induction (Bs), low coercive force (Hc), high hardness, and thermal stability of the structure. The films were produced by magnetron sputtering. The data obtained and published by the authors on the Fe–Ti–B films earlier indicate great prospects for their application in modern microelectronics. There are no any other published results of FeTiB film studies in the context of microelectronics applications. In this paper, we continue the studies of FeTiB films started earlier to identify the chemical and phase composition providing the level of properties required for film application in microelectronics. Nanocrystalline films containing 0 to 14.3 at.% Ti and 0 to 28.9 at.% B were obtained by DC magnetron sputtering. The phase-structural state of the films was studied by X-ray diffraction and transmission electron microscopy. All films are divided into 3 groups according to phase composition: single-phase (supersaturated solid solution of Ti in α-Fe), two-phase (α-Fe(Ti)/α-Ti, α-Fe(Ti)/TiB2, α-Fe (Ti)/FeTi, α-Fe(Ti)/Fe2B) and XRD amorphous. It is shown that XRD amorphous films feature by a mixed structure represented by a solid solution of α-Fe(Ti) with a grain size between 0.7 and 2 nm and an amorphous phase. A reasonable assumption is made on the amorphous phase enrichment by boron. A quantitative assessment of the α-Fe(Ti) phase grain size and its dependence on the chemical and phase composition of the films is given. The mechanisms of solid solution and dispersion hardening determine the grain size of this phase.