Cathodoluminescence Studies of Si-Sio2 Interfaces Prepared by Plasma-Assisted Oxidation and Subjected to Post-Oxidation Rapid Thermal Annealing

Abstract

ABSTRACTWe have used low energy cathodolumrdinescence spectroscopy (CLS) to characterize defects at ultrathin (50 Å) silicon dioxide films, prepared on Si substrates by low-temperature plasma deposition. Variable-depth excitation with different electron injection energies provided a clear distinction between deep levels localized within the films versus at their interfaces. Defect bands are evident at 0.8 eV and 1.9 eV, characteristic of an amorphous, silicon-rich local bonding environment. Closer to the film surface, CLS reveals a defect at 2.7 eV indicative of oxygen vacancies in stoichiometric SiO2. The effect of hydrogenation at 400°C, rapid thermal annealing at 900°C, and especially the combination of both processing steps is shown to reduce the density of these defects dramatically.