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Title page for ETD etd-11212006-101726


Type of Document Dissertation
Author Zhou, Xing
URN etd-11212006-101726
Title Charge Trapping Properties of Alternative High-k Dielectrics in MOS Devices
Degree PhD
Department Materials Science and Engineering
Advisory Committee
Advisor Name Title
Daniel M. Fleetwood Committee Chair
Bridget R. Rogers Committee Member
Robert A. Weller Committee Member
Ronald D. Schrimpf Committee Member
Sokrates T. Pantelides Committee Member
Keywords
  • hydrogen
  • trap charge density
  • alternative dielectrics
  • long-term reliability
  • microelectronic devices
Date of Defense 2006-10-12
Availability unrestricted
Abstract
High-k dielectrics are promising candidates to replace SiO2 in advanced integrated circuits in future space systems. Studies of the effects of ionizing radiation and bias-temperature stress (BTS) on high-k dielectrics were performed. Trapped charge densities are evaluated as functions of temperature and stress time. Prior radiation exposure enhances BTS-induced degradation in these devices. Worst-case responses in combined effects are positive (or zero) bias irradiation followed by NBTS for HfO2-based devices. Degradation due to oxide or interface trap-charge changes in magnitude with the bias polarity during switched-bias annealing either after irradiation or constant voltage stress (CVS). This demonstrates that metastable electron trapping (dominant during post-rad annealing) and hydrogen transport and reactions (dominant during post-CVS annealing) in the near-interfacial dielectric layers play significant roles in the defect formation process. Additional defect growth with time was observed as a result of additional charge injection through the gate stacks during the annealing process. These results provide insights into fundamental trapping properties of high-k dielectrics and can be used to help predict long-term reliability of these devices.
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