Correction of the Edge Effect in Auger Electron Microscopy

Abstract

The edge effect, which manifests itself especially in an edge over-brightening in images formed by shallow escape depth signals, is addressed. Attempts had been made to utilize the ratio technique which was developed for suppression of other spurious contrasts in Auger micrographs; it consists in relating the Auger signal to a suitable energy filtered background signal. A systematic comparison of a quantified edge effect in both the Auger images and the energy selected background images is reported here. Surface steps on Si and W surfaces and a W terrace edge on a Si substrate were used at 3 to 20keV primary electron energy, both low and high energy Auger electrons of Si and W were registered together with a background of up to 3 keV. Results have shown that the edge effect is less pronounced with the background so that any ratioing leads to an undercorrection. The best suppression (nearly acceptable for low energies, both primary and Auger ones) is obtained when using the background between 50 and 200 eV as the reference signal.

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