Growth and properties of single crystal TiN films deposited by reactive magnetron sputtering

Epitaxial stoichiometric (111)-oriented TiN films have been grown on cleaved MgO by dc reactive magnetron sputtering from pure Ti targets at substrate temperatures Ts ranging from 525–800 °C. The films were grown in mixed Ar/N2 discharges with the total sputtering pressure maintained constant at 3.5 mTorr (0.47 Pa). For Ts≲600 °C, N2 partial pressures PN2 that were either below or above a narrow range of values, which depended upon Ts, resulted in under- or over-stoichiometric films, respectively. However, at Ts≳600 °C, stoichiometric films could be obtained at any PN2, including pure N2, greater than a critical N2 partial pressure that varied from 0.2 to 0.4 mTorr (27 to 53 mPa) as Ts was increased from 600 to 800 °C. The Vickers hardness H, the room temperature resistivity ρ, and the temperature coefficient of resistivity TCR of stoichiometric TiN single crystals were found to be essentially independent of Ts and PN2. H was determined to be 2300±200 kg mm−2, about 15% higher than for bulk sintered TiN, ρ was 18 μΩ cm, and the TCR measured at temperatures between 100 and 400 K was 6200 K−1. The latter two results represent the lowest and highest values, respectively, yet reported for TiN films. The room temperature electron carrier concentration and mobility were determined from Hall measurements to be 5×1022 cm−3 and 6.7 cm2 V−1 s−1.