Nanocluster Memories by Ion Beam Synthesis of Si in SiO2


Nanocluster Memories by Ion Beam Synthesis of Si in SiO2

Schmidt, B.

Self-assembling of Si-nanocrystals (NCs) in gate oxides, with special emphasis on size and position tailoring and their application as discrete charge storage centers in nanocrystal memories area great challange to materials research with ion beams. The Si NCs for these multi-dot floating-gate memories have been produced by ion irradiation through SiO2/Si-interfaces. Si excess within SiO2 is formed by ion beam mixing of Si from the Si substrate and from the poly-Si capping layer into the gate oxide. Ion irradiation with 3x1015 -10x1015 Si+ cm-2 at 50-100 keV through 50 nm poly-Si and 15 nm SiO2 on (001)Si results in a considerable Si excess. At the upper and lower interfaces of the gate oxide, this ion irradiation forms a metastable SiOx composition. Si NCs are formed by phase separation into Si and SiO2 during post-irradiation thermal treatment. Adjacent to the recovering interfaces, narrow SiO2 zones becomes denuded of excess Si. More distant excess Si precipitates as Si NCs in the gate oxide. This approach was applied to nMOSFET-NC-memory fabrication in the standard CMOS line at ZMD. MOSFET characteristics in terms of write/erase voltage, duration of the programming time, endurance and retention have been evaluated.

Keywords: Ion beam irradiation; Si nanocrystals; MOSFET-nanocrystal memory

  • Lecture (Conference)
    2nd Workshop "Hybrid Nanostructured Materials - Synthesis, Properties, Applications", 08.-09.11.2006, Dresden, Germany
  • Open Access Logo Materials Science - Poland 25(2007)4, 1213-1222

Permalink: https://www.hzdr.de/publications/Publ-8989
Publ.-Id: 8989