Sputter depth profiling analysis of Ta2O5 on Si without preferential sputtering by energetic oxygen ion beams

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Abstract
Preferential sputtering has been one of the major problems in sputter depth profiling. Especially for compounds, preferential sputtering of one component leads to a change in the chemical state of the sample constituents. Therefore, accurate sputter depth profiling of the undistorted chemical state of sample constituents has not been possible. In this letter, we report that the preferential sputtering of oxygen atoms in the depth profiling of a Ta2O5 thin film on Si could be reduced quite successfully by using energetic oxygen ion beams with an appropriate incidence angle (30°) from the surface normal. By choosing an appropriate ion incidence angle, oxidation of the metallic Ta by the incident oxygen ion beams could be avoided as well. It was therefore possible to obtain an essentially undistorted sputter depth profile of the Ta in Ta2O5 on Si.