Journal of Vacuum Science & Technology A, Vol.19, No.5, 2174-2180, 2001
Improved Auger electron spectroscopy sputter depth profiling of W/WNx and WSix layers on Si substrates
We have investigated the effects of sample rotation and ion energy reduction on the quality of ion sputtering assisted Auger electron spectroscopy depth profiling of W/WNx and WSix films on polysilicon substrates. Rotation significantly improves both the depth resolution for W/WNx/Si samples and the sensitivity to oxygen inside the W/WNx film. Rotation does not have any effect on results for WSix/Si interfaces. Atomic force microscopy investigations show that the improved resolution for W/WNx/Si samples is due to reduced roughness of the sputtered surface when the sample is rotated. Reduction of the ion energy from 4 to 1 keV also improves the depth profiles of W/WNx films. The ion energy reduction in the same range leads to larger error in measured elemental concentrations for WSix films due to preferential sputtering, This reduction increases the depth resolution of Aug,er depth profiles in the case of polycrystalline WSix films, but does not change the depth resolution for amorphous WSix films.