Observation of an intermediate chemical state of silicon in the Si/SiO2 interface by Auger sputter profiling

Abstract

We have observed, for the first time, a chemical state of silicon different from that of the pure bulk silicon or silicon in SiO₂, using Auger electron spectroscopy. In the E N (E) spectra this state gives a major transition at 83.3 eV compared to 90.3 eV for bulk Si and 74.2 eV for SiO₂. We have observed this state both at the Si/SiO₂ interface of MOS oxide structures during sputter profiling and for thin native oxides without sputtering. The state is difficult to see in the dE N (E)/dE spectra due to the presence of the sharp edge of the free silicon peak at 92 eV which tends to mask it.