Paramagnetic defects at the interface of ultrathin oxides grown under vacuum ultraviolet photon excitation on (111) and (100) Si

Abstract

Electron-spin-resonance monitoring of Si dangling-bond-type interface defects is used to study ultrathin (∼20 Å) Si-oxide films grown by vacuum ultraviolet (VUV)-enhanced oxidation of Si at 300 K. Large densities (up to ∼9×1012 cm−2) of Pb and Pb0 centers (interfacial Si3≡Si⋅) are observed in VUV-grown (111) and (100) Si/SiO2, respectively. As compared to standard thermal Si/SiO2, two major differences emerge: the VUV Si/SiO2 interface is under substantially enhanced stress, while no Pb1 defects are discerned in VUV (100) Si/SiO2. It is inferred that Pb1 generation requires a minimum amount of oxide relaxation. Microscopic understanding is provided for the known inferior electrical interface quality threatening low-thermal-budget oxide fabrication.