Preferential sputtering effects in tantalum nitride thin films

Sputtered tantalum nitride thin films of two different compositions were bombarded with argon ions of energy 0.2–3 keV. Auger electron spectroscopy was employed to study the preferential enrichment of tantalum in the surface ofthe films as a consequence of the different tantalum and nitrogen sputtering yields. The results indicate that after the steady state is reached the magnitude of the relative enrichment of tantalum at the surface of the film is dependent on the energy of the argon ions. In addition, when the energy of the incident ions is changed (e.g. from 3 to 0.5 keV), transient variations in surface composition, which show a maximum in the tantalum concentration (a minimum in the nitrogen concentration), are observed and interpreted. The analysis of the composition profiles is completed by observing the evolution of the Auger signals corresponding to the carbon and oxygen present at low percentages in the sputtered TaN films.