The role of vacuum ultraviolet in H2 plasma treatment on SiO2 aerogel film

SiO2 aerogel film has been drawn an attention as excellent dielectric material due to its ultra low dielectric constant. SiO2 aerogel film could exhibit the improved electrical property after plasma treatment due to the removal of organic group. However, the role of vacuum ultraviolet (VUV) was not investigated in spite of high energy of VUV radiated during plasma processing. In this work, the radiation effect of VUV on SiO2 aerogel film was investigated during H2 plasma treatment. H2 gas was selected from its lightest atomic mass and strong photon emission in the VUV region. LiF single crystal was used as a VUV filter to permit the transmittance of the VUV radiated from H2 plasma but not with chemical species and reactive ions. It was found that VUV radiation during H2 plasma treatment plays a role of removal of organic group and rearrangement of siloxane bond.