Influence of high energy electron irradiation on the characteristics of polysilicon thin film transistors

  • P. V. Aleksandrova
  • V. K. Gueorguiev
  • Tz. E. Ivanov
  • S. Kaschieva
Solid and Condensed State Physics

Abstract.

The influence of high energy electron (23 MeV) irradiation on the electrical characteristics of p-channel polysilicon thin film transistors (PSTFTs) was studied. The channel 220 nm thick LPCVD (low pressure chemical vapor deposition) deposited polysilicon layer was phosphorus doped by ion implantation. A 45 nm thick, thermally grown, SiO2 layer served as gate dielectric. A self-alignment technology for boron doping of the source and drain regions was used. 200 nm thick polysilicon film was deposited as a gate electrode. The obtained p-channel PSTFTs were irradiated with different high energy electron doses. Leakage currents through the gate oxide and transfer characteristics of the transistors were measured. A software model describing the field enhancement and the non-uniform current distribution at textured polysilicon/oxide interface was developed. In order to assess the irradiation-stimulated changes of gate oxide parameters the gate oxide tunneling conduction and transistor characteristics were studied. At MeV dose of 6×1013 el/cm2, a negligible degradation of the transistor properties was found. A significant deterioration of the electrical properties of PSTFTs at MeV irradiation dose of 3×1014 el/cm2 was observed.

PACS.

61.80.Fe Electron and positron radiation effects 72.20.-i Conductivity phenomena in semiconductors and insulators 73.20.At Surface states, band structure, electron density of states 

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Copyright information

© EDP Sciences/Società Italiana di Fisica/Springer-Verlag 2006

Authors and Affiliations

  • P. V. Aleksandrova
    • 1
  • V. K. Gueorguiev
    • 1
  • Tz. E. Ivanov
    • 1
  • S. Kaschieva
    • 1
  1. 1.Institute of Solid State Physics, Bulgarian Academy of SciencesSofiaBulgaria

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