Synthesis of buried silicon oxide layers by water plasma immersion implantation

Buried silicon oxide layers were produced by water plasma immersion oxygen ion implantation and investigated by transmission electron microscopy, optical emission spectrometry, elastic recoil-detection analysis and Rutherford backscattering. Especially H2O+-ions, but also HO+-, O2+- and O+-ions, were implanted into silicon by pulse biasing the silicon wafer to a voltage between -40 and -50 kV. The pulse duration was 15 μs, the repetition rate was 200 Hz and the pulse number was varied between 0.92x105 and 29.5x105 pulses. The temperature during implantation was between 420 deg. C and 800 deg. C. The subsequent annealing process at 1250 deg. C for 5 h leads to buried silicon oxide layers with smooth interfaces. The shape of the oxygen concentration profiles is caused by superposition of the low-energy O+-ion and the high-energy H2O+- and HO+-ion profiles. The thickness of the damaged regions and the hydrogen contents decrease with increasing temperature. The application of water plasma has the advantage that the ion range is about twice the given ion energy because ionized oxygen atoms are implanted