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Title page for ETD etd-10082007-222617

Type of Document Master's Thesis
Author Chen, Dakai
Author's Email Address dakai.chen@vanderbilt.edu
URN etd-10082007-222617
Title Total dose irradiation effects on silicon and germanium MOS capacitors with alternative gate dielectrics
Degree Master of Science
Department Electrical Engineering
Advisory Committee
Advisor Name Title
Ron Schrimpf Committee Chair
Dan Fleetwood Committee Co-Chair
  • Metal oxide semiconductors -- Effect of radiation on
  • dysprosium
  • high-k
  • radiation
  • total dose
  • MOS
  • Hafnium
  • Dielectric devices -- Testing
  • Germanium
Date of Defense 2007-10-16
Availability unrestricted
Alternative dielectrics are rapidly becoming necessary for the future of Metal-Oxide-Semiconductor (MOS) devices, as SiO2-based technology reaches scaling limits. In this thesis, the total ionizing dose irradiation effects on Si and Ge MOS capacitors with Hf-based gate dielectrics are investigated. The radiation response of the HfO2/Dy2O3 on Ge MOS devices exhibited no change in the capacitance-voltage characteristics. HfO2 has the tendency to trap large amounts of electrons relative to SiO2. However the high gate leakage current likely efficiently neutralized any radiation-induced charge build-up for these devices. We have also examined the radiation response and bias-temperature effects of Si MOS devices with HfSiON gate dielectrics. The results showed much improved radiation hardness relative to earlier Hf silicate devices (net oxide-trapped charge density ~ 16× less). The low-Si3N4 content film also displayed enhanced charge trapping relative to the high-Si3N4 content film. In addition, the HfSiON devices showed much reduced degradation from bias-temperature stress relative to SiO2 and HfO2 devices. However the improved bias-temperature stability likely results from difference in processing techniques, and comes at the cost of high density of process-induced interface traps. The material properties and processing techniques can significantly influence the reliability and radiation response of high-k MOS devices. The work in this thesis provides insights to the reliability and radiation degradation that are essential to the development of Hf-based MOS devices.

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