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Application of the analytical methods REM/EDX, AES and SNMS to a chlorine induced aluminium corrosion

Scanning electron microscopy - SEM - with energy dispersive X-ray detection - EDX -, Auger electron spectroscopy - AES - and sputtered neutral mass spectrometry - SNMS - have been used to characterize a chlorine induced corrosion of an aluminium metallisation. SEM/EDX detects the characteristic X-rays that are emitted from the first few micrometers beneath the specimens surface after inner shell ionisation by the primary electrons. AES detects the alternatively ejected Auger electrons that are generated within the topmost atomic layers of the sample. To obtain elemental concentration depth profiles, the surface layers are removed by ion sputtering. Whereas AES detects the composition of the remaining surface, SNMS measures sputtered fluxes and does not suffer from preferential sputtering. As demonstrated by the example of a chlorine induced aluminium corrosion, these analytical methods are complementary with respect to quantification, chemical information and information depth. Only by simultaneous use measuring artefacts are detectable and able to be excluded from interpretation.