Crystal Orientation of Epitaxial α-Ta(110) Thin Films Grown on Si(100) and Si(111) Substrates by Sputtering

We have prepared Ta thin films on Si(100) and Si(111) substrates by increasing the substrate temperature from room temperature (RT) to 500 °C, using an ultrahigh-vacuum dc magnetron sputtering system. The obtained film crystallinities were evaluated by X-ray diffraction and X-ray pole figure analyses. It was found that the crystal phase of the prepared Ta films transforms gradually from the β-Ta phase to the α-Ta phase with increasing substrate temperature, and the epitaxial growth of the α-Ta(110) plane was realized at substrate temperatures of 400 °C on Si(100) and 200 °C on Si(111). In addition, it was also clarified that the α-Ta(110) films are grown epitaxially in a twin state on Si(100), while they are grown epitaxially in a triplet state on Si(111).