The influence of pressure and magnetic field on the deposition of epitaxial TiBx thin films from DC magnetron sputtering

• Published in: Vacuum 2020-07, Vol.177, p.109355, Article 109355
• Main Authors: Nedfors, Nils, Primetzhofer, Daniel, Zhirkov, Igor, Palisaitis, Justinas, Persson, Per O.Å., Greene, J.E., Petrov, Ivan, Rosen, Johanna
• Format: Article
• Language: English
• Subjects: Epitaxial; Magnetic field; Magnetron sputtering; Sputtering pressure; Titanium diboride
• ISSN: 0042-207X; 1879-2715; 1879-2715
• DOI: 10.1016/j.vacuum.2020.109355

Magnetron sputter deposition of TiBx thin films from a TiB2 target typically results in highly overstoichiometric films due to differences in sputtered-atom ejection angles and gas-phase scattering during transport to the substrate. This study investigates the effects of the magnetron magnetic field strength at the substrate position and the Ar sputtering pressure on the resulting film composition and crystalline quality. It is shown that the B/Ti atomic ratio can be reduced from 2.7 to 2.1 by increasing the Ar pressure from 5 mTorr to 20 mTorr, a trend consistent with previous work. Despite the use of a relatively high Ar pressure, a change to a stronger outer magnetic pole leads to, dense TiB2.1 films of high crystal quality, as shown by X-ray diffraction, scanning transmission electron microscopy, and specific resistivity of 32 μΩcm. For epitaxial films deposited at 900 °C on Al2O3(001), a TiB2[110]//Al2O3[100] orientational relationship were obtained. •An increase in Ar pressure from 5 to 20 mTorr reduce B/Ti ratio from 2.8 to 2.1•An increase in magnetic field strength from 29 G to 40 G improves film density.•Epitaxial, dense, TiB2.1 films have been grown on Al2O3 (001) at 900 °C.