Titanium nitride oxidation chemistry: An x-ray photoelectron spectroscopy study

We report a study of the oxidation of TiN. In previous work, the oxidation kinetics for 350-450 °C were reported and an initiation time prior to fast oxidation was identified. In this study, x-ray photoelectron spectroscopy was used to investigate the oxidation mechanisms at 350 °C during this initiation time period. The oxide thickness increases slowly with oxidation time and the film appears to change from an amorphous TiO₂ layer to a crystalline TiO₂ layer. Spectral features which are intermediate between TiO₂ and TiN are reported and a model involving grain boundary oxidation is proposed. One of the thicker oxides studied was annealed in vacuum to 700 °C. Following oxidation, some of the capping oxide and much of the intermediate material is no longer in the analysis volume and we suggest that the oxygen and nitrogen is being dissolved into the bulk in much the same way that nonevaporable getters are activated before use.