Structural imperfections in silicon dioxide films identified with vacuum ultraviolet optical absorption measurements

The optical absorption of silicon dioxide films fabricated by dry oxidation at 1000 or 1100 °C was studied by measurements in the vacuum ultraviolet region. Two clear absorption bands at 7.6 and 6.7 eV were found for the films. Intensities of the bands decreased following heat treatment in a H2 ambient. The absorption band at 7.6 eV is considered to be caused by the defect having the structure of 3O≡SiSi≡O3. The concentration of the 3O≡SiSi≡O3 structure was estimated to be 6×1019 cm−3 and 5×1018 cm−3 for the films fabricated at 1000 and 1100 °C, respectively.