EPMA Sputter Depth Profiling, Part II: Experiment

Abstract

Electron probe x-ray microanalysis (EPMA) has been developed into a reliable technique for surface layer analysis but, due to the relatively large depth of information, it cannot yet be applied to resolve complex depth distributions, i.e. layers with concentration gradients or complex multilayer structures.

To improve the depth resolution of EPMA we combined an ion gun with a conventional microprobe analyzer, forming the technique of EPMA sputter depth profiling (EPMA-SDP). This arrangement allows the continuous removal of the surface and simultaneous measurement of emitted x-ray intensities as a function of sputtered depth. In this paper the experimental arrangement is described and first results are presented. The sample analysed is a Cu/NiCr/Cu/ NiCr…/Si multilayer, a structure which could not be determined with a standard EPMA method such as beam energy variation. However with EPMA-SDP the mass coverage of each layer as well as its chemical composition was established directly from the measured data with an accuracy of about ±5% relative. The theoretical background of the new technique is described in part I of the paper (this volume).

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