Phase tailoring of Ta films via buffer layer-thicknesses controlling

Hard beta-Ta phase is generally produced during Ta film deposition. While in some cases, soft alpha-Ta phase is preferred to ensure deformation capability. In this work, templated growth strategy by introducing Cr buffer layer is proposed to tailor the phase composition in Ta films. A broad spectrum of beta-Ta/alpha-Ta ratio from 90% to 0% can be continuously and precisely achieved when the buffer layer thickness is correspondingly controlled from 0 to similar to 90 nm. Hardness of the Ta films is well proportional to the beta-Ta/alpha-Ta ratio. The underlying mechanism of phase tailoring is rationalized by demonstrating the thickness-dependent crystallization of buffer layer.

Automated summary

In this study, a templated growth strategy by introducing a Cr buffer layer is proposed to tailor the phase composition in Ta films. The beta-Ta/alpha-Ta ratio in the films can be continuously and precisely controlled by adjusting the thickness of the buffer layer, resulting in different hardness of the Ta films.