Topographic compensation in Auger electron spectroscopy

The scanning Auger microprobe (SAM) produces Auger images which provide information on the elemental distribution of specimen surfaces. However specimen topography affects the data obtained. To eliminate the topographical effect, the peak‐to‐background ratio, ( P − B )/ B ( = R ), is often used instead of the net peak intensity, P − B . It was found that this method would provide reasonable quantitative results when the tilting angle of the facet plane against the primary electron beam incidence is less than approximately 50°. Over 50°, R would generally give higher values. At 80° R would be 1.2–3.7 times larger than that at 0°. In this paper we propose a new method to compensate for this deviation. Through specimen tilting experiments using a flat surface, we found a deformation of total background shape at high tilting angles. It is interpreted by γ, a background intensity ratio at two energies (ex. 2000 eV and 3000 eV). It was found that γ obeys a simple equation of tilt angle θ,\documentclass{article}\pagestyle{empty}\begin{document}$$ \gamma (\theta) = 7 \times 10^{ - 5} \theta ^2 - 2.92 \times 10^{ - 3} \theta + 1 $$\end{document} . Then, θ can be derived from the values of the background intensity ratios. The following relationship was also found between R 0 and R\documentclass{article}\pagestyle{empty}\begin{document}$$ R_0 = R_0 /[(1.47 \times 10^{ - 3} E + 0.06){\rm exp }\{ 6.1 \times 10^{ - 4} (\theta - 45)^2 \} + 1] $$\end{document}where R 0 and R θ are peak‐to‐background ratios at 0 and θ degrees, respectively, and E is the Auger transition energy. Since θ can be derived, we can always connect the peak‐to‐background ratio at θ to that in the horizontal state. Thus, elimination of topographic effect would be possible. We believe that this scheme would contribute to quantitative Auger imaging.