Characterization of SiO2/Si(100) interface structure of ultrathin SiO2 films using spatially resolved electron energy loss spectroscopy

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Abstract
High‐resolution transmission electron microscopy (HRTEM) with 0.3‐nm resolution, scanning transmission electron microscopy using transmission electron diffraction and electron energy loss spectroscopy (EELS) with 0.7‐nm resolution have been employed to characterize the SiO2/Si(100) interface structure of ultrathin (5–12 nm) SiO2 films grown by rapid thermal oxidation (RTO) at 1100 °C. In the HRTEM image, the SiO2/Si(100) interface of ultrathin SiO2 film grown by RTO in dry oxygen ambient seems to be uniform. The TED patterns also showed that the atomic structure abruptly changes from the crystalline silicon to amorphous oxide network across the SiO2/Si interface. The EELS plasmon‐loss spectra showed that for 5‐nm‐thick SiO2 an intermediate oxide composition indicating a plasmon energy between Si (17.0 eV) and SiO2 (22.5 eV) is present, whereas it disappears for 12‐nm‐thick SiO2 film.