Ion-beam assisted synthesis and thermal oxidation of TiN thin films combined with in-situ, depth-resolved characterization using MeV ions

We present an in-situ, depth-resolved and non-destructive approach to assess the chemical composition of titanium nitride (TiN) thin films during synthesis and controlled oxidation. Ion beam assisted deposition was used to deposit a TiN sample of approximately 120 nm thickness. The chemical composition was characterized in the deposition environment using non-destructive Rutherford/Elastic Backscattering Spectrometry (RBS/EBS), with a depth resolution of ca. 25 nm. The high sensitivity of the measurements to the non-metallic species was ensured by the use of elastic resonances. Analysis revealed a few percent oxygen incorporated in the films due to residual gases during growth. After deposition, the TiN film was exposed to oxygen at step-wise increasing temperatures, and the composition of the film was analyzed after every annealing step. The measurements provide a direct proof of inward oxidation with associated concentration gradients, starting with oxygen absorption without significant nitrogen release when using moderate annealing temperatures (250–310 °C), where the oxygen content tends to saturation. At 710 °C, above the oxidation onset temperature, atomic composition data indicate N loss parallel to the O uptake. However, ex-situ transmission electron microscopy showed no evidence of any oxide phase, implying that oxidation starts without crystallite formation. •Titanium nitride was deposited, then exposed to O2 at increasing temperatures.•Ion beam assisted deposition, controlled modification and analysis in one equipment.•Depth-resolved, non-destructive chemical analysis by RBS•Oxidation starts with O absorption at 250 °C, followed by N displacement at 710 °C.•Transmission electron microscopy showed no evidence of TiO2 crystallite formation.