Auger electron spectroscopy (AES) and X-ray photoelectron spectroscopy (XPS) are very famous for elemental and chemical state analysis at a solid surface. In generally, XPS has been utilized for these analysis in an area of more than a few 100 mm² on a solid surface. In contrast, AES has been used rarely for chemical state analysis, but for elemental analysis at a minute area of less than 100 mm². The reason for it is approximately caused by the following three problems.

Among these problems, No.2 and No.3 can be solved in many cases by some special pre-sampling and measurement techniques. However No.1 has been recognized as the biggest problem for the chemical state analysis in AES because some commercial Auger instruments could not obtain sharper peaks in a spectrum with a poor energy resolution of 0.5-0.6 % or the others could not have a sufficient sensitivity with an energy resolution of higher 0.1 %. So, the chemical state analysis in AES has been carried out only for some specific elements showing a bigger chemical shift of more than a few eV.

Now we had measured more than 400 standard spectra by the latest analyzer for pure materials or compounds with the energy resolution of higher than 0.1 %, which included shaper peaks and fine structures with little electron beam damage. Those spectra show that Auger spectra for compounds have different peak shapes and different peak positions.So, it is possible to distinguish them by the peak shape difference, even if some standard spectra of different chemical states have quite similar peak positions each other.

In this report, we can propose an advanced chemical state analysis by higher energy resolution AES, which is a spectrum separation method from a practical spectrum including several chemical states by comparison of peak shape difference. As an example application, this method was applied for the depth profile result of a natural oxide layer on a pure tin oxide plate with an energy resolution of 0.1 %. The result showed that it was clearly consisted of three layers (SnO₂/SnO/Sn subst.) by the waveform separation of Sn MNN to each chemical condition of Sn⁴⁺, Sn²⁺, and Sn⁰. Moreover, it was found that the quantitative analysis of chemical state of Sn was also possible by comparison of the absolute intensity of standard spectrum.