Impact of moisture from ambient on ion beam synthesis of nanocrystals in thin SiO2 layers


Impact of moisture from ambient on ion beam synthesis of nanocrystals in thin SiO2 layers

Schmidt, B.; Heinig, K.-H.; Grambole, D.; Herrmann, F.; Perego, M.

The scaling-down of the gate oxide thickness in modern MOS memory devices below 20 nm requires low energy ion implantation for ion beam synthesis (IBS) of nanocrystals (NC) in SiO2. Lowering the ion energy, the implanted and damaged SiO2-layer will be located closer to the SiO2 surface and the interaction of this layer with the ambient becomes more and more dangerous. In the damaged near surface layer the high number of broken bonds due to displaced Si and O atoms forms in the glassy network pathes, which are open for diffusion and in which moisture from the ambient can be absorbed. Therefore chemical reactions of the implanted impurities with hydrogen and oxygen must be expected during subsequent annealing. Water 16, H2O18) absorption in Si-, Ge-, and Sn-implanted SiO2 layers has been studied by H-depth profiling using Nuclear Reaction Analysis (NRA) and by O18-depth profiling using Time-of-Flight Secondary Ion Mass Spectrometry (ToF-SIMS), respectively. H- and O-depth profiles were measured after storage under clean room conditions and after additional wet cleaning, as well as after annealing. The amounts of H and O incorporated into as-implanted SiO2 already during storage are comparable with the concentration of the implanted impurities and are sufficient to interfere significantly with the precipitation and Ostwald-ripening of NCs during IBS.

  • Lecture (Conference)
    International Workshop on Nanostructures for Electronics and Optics - NEOP - Dresden, Germany October 6 - 9, 2002
  • Contribution to proceedings
    International Workshop on Nanostructures for Electronics and Optics - NEOP - Dresden, Germany October 6 - 9, 2002

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Publ.-Id: 5129