Similar chemical state information is also contained in the Si 2p spectra shown in Figure 4, where the spectra are shown as a function of depth from the surface. At the surface, where the TiN overlayer is expected to completely attenuate the Si 2p signal it is noted that there is still some signal at 99eV binding energy. This is thought to be due to the Si substrate exposed during sample preparation, as it remains constant through the TiN and SiO₂ layers. After removal of the TiN overlayer, the Si 2p signal from the SiO2 layer is observed at 103.5eV binding energy. Further removal of surface material exposed the Si substrate, characterized by the elemental Si 2p photoemission peak at 99.3eV.

Figure 4: Si 2p spectra as a function of depth from the surface.

Summary

X-ray photoelectron spectroscopy using the AMICUS instrument is an invaluable tool for the characterization of thin film materials. The fully automated operation using VISION control software allows repetitive depth profiling to be completed with ease.
The key features of AMICUS demonstrated are:
•     Concentration depth profiling,
•     Unsupervised, fully computer controlled data collection using VISION software,
•     Chemical state determination of surface atoms.