Topographic Compensation in Auger Electron Spectroscopy

Scanning Auger microprobe (SAM) images provide information on the elemental distribution of specimen sdurfaces, but the data are influenced by specimen topography. To climinate this 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 these mothods would provide reasonable quantitative results when the tilting angle of the facet plane against the primary electron beam incidence is less than approx. 50 degrees. Over 50 deg., the R would generally give higher values, and at 80 deg., the value is 1.23.7 times larger than that at 0 deg. We propose a new method to compensate for this deviation. Through spcimen tilting experiments, we found a deformation in 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). Since, γ obeys a simple equation of tilt angle θ, γ(θ)=7×10-5θ2-2.92×10-3θ+1 Then the θ can be derived the background intensity values. The following relationship was also found between R0 and Rθ R0=Rθ/[(1.47×10-3E+0.06) exp {6.1 × 10-4(θ-45)2} + 1] where R0 and Rθ are peak to background ratios at 0 and θ deg., respectively, and E is the Auger transition energy. Since θ can known, we can always get the peak to background ratio values converted to the horizontal state. Elimination of topographic effect would thus be possible. We believe that this scheme would contribute to quantitative Auger imaging.