X-ray photoelectron spectroscopy study of Al/Ta2O5 and Ta2O5/Al buried interfaces

Buried interfaces of thin ${\mathrm{Al/Ta}}_{\mathrm{2}}{\mathrm{O}}_{\mathrm{5}}$ and ${\mathrm{Ta}}_{\mathrm{2}}{\mathrm{O}}_{\mathrm{5}}\mathrm{/Al}$ films were studied using the x-ray photoelectron spectroscopy technique. The peak decomposition technique was employed to identify the composition and chemical states at the interface region. It was observed that there is an “intermixing layer” at the ${\mathrm{Al/Ta}}_{\mathrm{2}}{\mathrm{O}}_{\mathrm{5}}$ interface, where ${\mathrm{Ta}}_{\mathrm{2}}{\mathrm{O}}_{\mathrm{5}}$ has been reduced to lower binding energy states due to the reaction of Al with ${\mathrm{Ta}}_{\mathrm{2}}{\mathrm{O}}_{\mathrm{5}}$ during deposition. On the other hand, the ${\mathrm{Ta}}_{\mathrm{2}}{\mathrm{O}}_{\mathrm{5}}\mathrm{/Al}$ interface is relatively stable, consisting of ${\mathrm{Ta}}_{\mathrm{2}}{\mathrm{O}}_{\mathrm{5}}$ and ${\mathrm{Al}}_{\mathrm{2}}{\mathrm{O}}_{\mathrm{3}}$ interfacial layers. Based on a uniform multilayer structure model, the thickness of the interfacial layers was estimated by using the relative photoelectron intensities.