ACCURACY OF FILM THICKNESS DETERMINATION IN ELECTRON-PROBE MICROANALYSIS

The thickness of copper films (100-450 nm) on silicon substrates was d etermined by electron probe microanalysis (EPMA) applying phi(rho z) p rocedures of Pouchou and Pichoir. Film thickness was calculated from e xperimental k-ratios analyzed with electron energies between 6 and 30 keV using commercial software (LAYERF distributed by CAMECA). The infl uence of the incident electron energy and X-ray line chosen for analys is on the results was investigated. Accuracy of film thickness determi nation was evaluated by comparison with Rutherford backscattering spec troscopy (RBS) and secondary ion mass spectrometry (SIMS). The differe nce between layer thicknesses determined with EPMA and RBS is in gener al less than 2%, if EPMA measurements are performed with various elect ron energies. Layer thicknesses determined with Cu-L alpha are mostly closer to values obtained by RBS than those derived from Cu-K alpha ra diation. Preliminary SIMS measurements yielded inconsistent results an d, thus, cannot be used in this case to determine the layer thickness of Cu films on Si accurately.