Thermal stability under air of tungsten–titanium diffusion barrier layer between silica and platinum

• The thermal stability of SiO2/Ti–W/Pt structure under air has been studied.
• Oxidation, diffusion and sublimation processes occurred during annealing.
• Film surface chemistry and microstructure were correlated with diffusion phenomena.
• We proposed WO3 diffusion mechanisms through platinum film.
• The WO3 diffusion mechanisms are mainly governed by the layer microstructure.

The present work investigated the thermal stability of tungsten–titanium diffusion barrier layers intercalated between SiO2 substrate and platinum thin film. The resulting structures were annealed under air in the temperature range 400–600 °C for annealing times up to 100 h. Chemical and structural characterizations at different stages of the treatment evidenced several phenomena occurring during annealing under air, especially the complete oxidation of the adhesive layer, the diffusion of tungsten oxide through platinum film at particle boundaries as well as the sublimation process of tungsten oxide. The results of film surface chemistry and microstructure were correlated with diffusion phenomena.