Radiation Damage in SiO₂/Si Induced by VUV Photons

Quantitative measurements of radiation damage in SiO 2 /Si systems induced by VUV photons generated in various microwave plasmas are performed. The SiO 2 /Si system is irradiated by monochromatic VUV photons, and its flat-band voltage shift ( Δ V FB ) is measured by the C-V method. The number of effective positive charges generated in the SiO 2 layer by a single VUV photon ( R f ) is evaluated from the Δ V FB and the total VUV dose. A VUV photon is found to generate effective positive charges in SiO 2 when its energy ( E p ) is larger than the SiO 2 band gap energy ( E g =8.8 eV). The value of R f is on the order of 10 -3 ∼10 -2 and increases in proportional to the energy difference between E p and E g . A model is proposed to explain these phenomena. The model states that a VUV photon with energy E p (> E g ) generates an electron-hole pair in the SiO 2 and the holes that are not recombined are trapped in the energy state near the SiO 2 /Si interface.