Ar incorporation in epitaxial TiN films deposited by reactive magnetron sputtering in mixed Ar/N2 discharges

Abstract

TiN films were grown on (100), (110), and (111) oriented MgO by reactive magnetron sputtering from a Ti target in mixed Ar/N2 discharges. During film growth at substrate temperatures Ts ranging from 450 to 900 °C, an applied negative substrate bias Vs (0≤Vs≤600 V) was used to vary the flux and energy of impinging Ar+ and N+2 ions. Electron channeling and transmission electron microscopy were used to show that films grown at Ts≥550 °C were epitaxial with a defect density that decreased with increasing Ts. At a constant Ts=700 °C, the films were found to remain epitaxial as Vs was increased from 0 to 200 V, but the crystalline quality clearly deteriorated with Vs=400 V and at Vs=600 V the films were polycrystalline. Energy dispersive x-ray analysis showed that the trapped Ar concentration CAr in the films was a function of both Vs and Ts. For Ts=700 °C, CAr increased with increasing Vs to reach a maximum CmaxAr at 400 V before decreasing again. The relative value of CmaxAr varied with orientation in the following manner: (110)>(100)>(111). At a constant Vs=400 V, CmaxAr for (110) oriented films occurred at Ts≊750 °C. These results are explained based upon ion channeling efficiency as a function of film orientation and defect structure.