Radiation induced charge trapping in ultrathin HfO 2-based MOSFETs

Sriram K. Dixit, Xing J. Zhou, Ronald D. Schrimpf, Daniel M. Fleetwood, Sokrates T. Pantelides, Rino Choi, Gennadi Bersuker, Leonard C. Feldman

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Abstract

Radiation induced charge trapping in ultrathin HfO 2-based n-channel MOSFETs is characterized as a function of dielectric thickness and irradiation bias following exposure to 10 keV X-rays and/or constant voltage stress. Positive and negative oxide-trap charges are observed, depending on irradiation and bias stress conditions. No significant interface-trap buildup is found in these devices under these irradiation and stress conditions. Enhanced oxide-charge trapping occurs in some cases for simultaneous application of constant voltage stress and irradiation, relative to either type of stress applied separately. Room temperature annealing at positive bias after irradiation of transistors with thicker gate dielectric films leads to positive oxide-trapped charge annihilation and/or neutralization in these devices, and net electron trapping. The oxide thickness dependence of the radiation response confirms the extreme radiation tolerance of thin HfO 2 dielectric layers of relevance to device applications, and suggests that hole traps in the thicker layers are located in the bulk of the dielectric. A revised methodology is developed to estimate the net effective charge trapping efficiency, f ot, for high-re dielectric films. As a result, estimates of f ot for Hf silicate capacitors and Al 2O 3 transistors in previous work are reduced by up to 18%.

Original languageEnglish
Pages (from-to)1883-1890
Number of pages8
JournalIEEE Transactions on Nuclear Science
Volume54
Issue number6
DOIs
Publication statusPublished - Dec 1 2007

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Keywords

  • Constant-voltage-stress (CVS)
  • Hafnium oxide (HfO )
  • High-κ
  • Metal-oxide-semiconductor-field-effect-transistors (MOSFETs)
  • Radiation damage
  • Recovery
  • Ultrathin
  • X-ray

ASJC Scopus subject areas

  • Nuclear and High Energy Physics
  • Nuclear Energy and Engineering
  • Electrical and Electronic Engineering

Cite this

Dixit, S. K., Zhou, X. J., Schrimpf, R. D., Fleetwood, D. M., Pantelides, S. T., Choi, R., Bersuker, G., & Feldman, L. C. (2007). Radiation induced charge trapping in ultrathin HfO 2-based MOSFETs. IEEE Transactions on Nuclear Science, 54(6), 1883-1890. https://doi.org/10.1109/TNS.2007.911423