Obtaining different orientation relationships for Cu films grown on (0001) α-Al₂O₃substrates by magnetron sputtering

Abstract

Cu films were grown on (0001) α-Al 2 O 3 single-crystals by magnetron sputtering. The growth behavior was manipulated by Ar + -ion sputter cleaning of the substrates at kinetic energies between 100 and 500 eV, changing the sputter rate from 0.75 to 1.1 nm/s, and using nominal substrate temperatures of 100 and 200°C, respectively. Polycrystalline Cu films formed on α-Al 2 O 3 substrates after an Ar + -ion bombardment at 500 eV, while epitaxial Cu films evolved when Ar + -ion energies of 100 and 200 eV were used. The epitaxial Cu films always consisted of two twin-related growth variants. However, two different orientation relationships emerged which differ by a 30° in-plane rotation of the (111) oriented Cu films when the deposition rate is changed from 0.75 to 1.1 nm/s. The results will be discussed on the basis of differences in the growth process.