KINETICS AND MECHANISMS OF TIN OXIDATION BENEATH PT THIN-FILMS

Oxidation kinetics are reported for TiN thin film diffusion barriers b eneath polycrystalline Pt films of 50-200 nm thickness annealed in dry O-2/N-2 ambients of varying oxygen partial pressure and total pressur e near 1 atm. Oxygen resonance backscattering spectrometry was used to detect thin oxide layers at the Pt/TiN interface produced by oxidatio n annealing at 475-650 degrees C. Over part of this temperature range, a linear oxidation rate law was observed for the buried TiN film, ind icating the oxidation rate was independent of average titanium oxide t hickness. Possible rate-controlling oxidation mechanisms are analyzed critically in light of the kinetic data and results from microstructur al studies of the Pt/TiN specimens. We conclude that the rate-limiting step in the Pt/TiN oxidation process is diffusion of oxygen through t he Pt grain boundaries. (C) 1997 American Institute of Physics. [S0021 -8979(97)06821-7].