Charge trapping in high-Κ gate dielectrics: A recent understanding

D. Misra, N. A. Chowdhury

Research output: Chapter in Book/Report/Conference proceedingConference contribution

6 Scopus citations

Abstract

Charge trapping in Hf-based high-κ dielectrics, used in MOS transistor gate stacks, causes threshold voltage shift (ΔV T) during constant voltage stress (CVS). It seemed to be very transient due to the presence of a large number of shallow traps and can be eliminated by applying a reverse direction electric field. Recent findings, however, suggest that deep traps significantly contribute to the reliability of various Hf-based high-κ gate stacks. The origin of the deep traps and their dependence on O vacancy formation during dielectric deposition is discussed. ΔV FB and leakage current dependence on these deep traps is also outlined. It is shown that trapping at deep levels inhibits fast ΔV T recovery. We have experimentally observed trap levels from low temperature measurements assuring the presence of O vacancies in Hf-silicate based films. Substrate hot electron (SHE) injection gives rise to significant electron trapping and slow post-stress recovery under 'negative bias' conditions, which confirms that O vacancy induced deep defects determine the transient behavior in Hf-silicate based high-κ gate dielectrics. It is further shown that negative-U transition to deep defects is responsible for trap assisted tunneling under substrate injection. A fraction of the injected electrons remains trapped at the deep defects and gives rise to significant ΔV FB. This has the potential to be the ultimate limiting factor for the long-term reliability of Hf-based high-κ gate dielectrics. Copyright The Electrochemical Society.

Original languageEnglish (US)
Title of host publicationDielectrics for Nanosystems II
Subtitle of host publicationMaterials Science, Processing, Reliability, and Manufacturing
Pages311-328
Number of pages18
Edition1
StatePublished - Jul 3 2006
Event2nd International Symposium on Dielectrics for Nanosystems: Materials Science, Processing, Reliability, and Manufacturing - 209th Meeting of the Electrochemical Society - Denver, CO, United States
Duration: May 7 2006May 12 2006

Publication series

NameECS Transactions
Number1
Volume2
ISSN (Print)1938-5862
ISSN (Electronic)1938-6737

Other

Other2nd International Symposium on Dielectrics for Nanosystems: Materials Science, Processing, Reliability, and Manufacturing - 209th Meeting of the Electrochemical Society
CountryUnited States
CityDenver, CO
Period5/7/065/12/06

All Science Journal Classification (ASJC) codes

  • Engineering(all)

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