Abstract
Quantitative measurements of radiation damage in SiO2/Si systems induced by VUV photons generated in various microwave plasmas are performed. The SiO2/Si system is irradiated by monochromatic VUV photons, and its flat-band voltage shift (ΔVFB) is measured by the C-V method. The number of effective positive charges generated in the SiO2 layer by a single VUV photon (Rf) is evaluated from the ΔVFB and the total VUV dose. A VUV photon is found to generate effective positive charges in SiO2 when its energy (Ep) is larger than the SiO2 band gap energy (Eg=8.8 eV). The value of Rf is on the order of 10-3∼10-2 and increases in proportional to the energy difference between Ep and Eg . A model is proposed to explain these phenomena. The model states that a VUV photon with energy Ep(>Eg) generates an electron-hole pair in the SiO2 and the holes that are not recombined are trapped in the energy state near the SiO2/Si interface.