Studies on the structure of the SiOx/SiO2 interface

We report X-ray photoelectron spectroscopy (XPS), X-ray induced Auger electron spectroscopy (XAES), and synchrotron radiation photoemission results of the effects induced by Ar+ ion etching on the chemical composition of the SiO2/Si interface and of SiO2. XPS and AES spectroscopies are used as indicators of the artifacts induced by 2 keV Ar+ ions during the depth profile of an SiO2/Si system. The only etching-induced spectral change we observe is a symmetrical broadening of signal widths, which we ascribe to amorphization and, possibly, to roughening phenomena, whereas the genuine chemical composition at the interface itself is not substantially altered by the impacting ions. Occurrence of SiO(x) damage species in silica is evaluated as a function of both the argon energy (0.5-4 keV) and the depth sensitivity of analysis (4-30 angstrom). We find that SiO(x) are evidenced only if the depth of damage matches the attenuation length of the electron analyzed.