Kinetics and mechanisms of TiN oxidation beneath Pt thin films

Oxidation kinetics are reported for TiN thin film diffusion barriers beneath polycrystalline Pt films of 50–200 nm thickness annealed in dry O2/N2 ambients of varying oxygen partial pressure and total pressure near 1 atm. Oxygen resonance backscattering spectrometry was used to detect thin oxide layers at the Pt/TiN interface produced by oxidation annealing at 475–650 °C. Over part of this temperature range, a linear oxidation rate law was observed for the buried TiN film, indicating the oxidation rate was independent of average titanium oxide thickness. Possible rate-controlling oxidation mechanisms are analyzed critically in light of the kinetic data and results from microstructural studies of the Pt/TiN specimens. We conclude that the rate-limiting step in the Pt/TiN oxidation process is diffusion of oxygen through the Pt grain boundaries.