COMBINED EPMA AND AES DEPTH PROFILING OF A MULTILAYER TI-AL-O-N COATING

In order to compare thin-film electron probe microanalysis (EPMA) and Auger electron spectroscopy (AES) regarding reliability in quantifying chemical compositions of Ti-Al-O-N coatings with depth, a multilayer was prepared on a silicon wafer by using reactive ionized cluster beam deposition technique. Within a total thickness of about 25 nm the com position of the multilayer varied step by step from Ti-Al-O-N at the b ottom to Al-0 at the top. AES and, as an innovation, EPMA crater edge profiling was applied to measure the composition with depth. For quant ification special thin-film EPMA techniques based on Monte Carlo simul ations were applied. The chemical binding states of Al and Ti with dep th were analysed using a high resolution energy analyser (MAC 3) for t he AES investigations working in the direct mode. According to the dep osition procedure the concentration profiles of the components varied with depth for both AES and EPMA measurements. AES provided a better d epth resolution than EPMA. To get a true calibration of the depth scal e an in-situ measurement method like an optical interferometry will be required. Assuming that the relative sensitivity factors are availabl e AES depth profiling delivers concentration profiles with good accura cy. The new EPMA application provided quantitative depth profiles conc erning concentration and coverage. For EPMA crater edge profiling the coating needs to be deposited on a foreign substrate because depth dis tributions of elements being present in both the layer and the substra te cannot be resolved. The combination of AES-depth profiling with EPM A crater edge profiling techniques is a powerful tool to analyse heter ostructures quantitatively.