The role of nitrogen-related defects in high-k dielectric oxides: Density-functional studies

Research output: Contribution to journalArticleScientificpeer-review

Researchers

Research units

  • University College London
  • SEMATECH

Abstract

Using ab initio density-functional total energy and molecular-dynamics simulations, we study the effects of various forms of nitrogen postdeposition anneal (PDA) on the electric properties of hafnia in the context of its application as a gate dielectric in field-effect transistors. We consider the atomic structure and energetics of nitrogen-containing defects which can be formed during PDA in various N-based ambients: N2, N2+, N, NH3, NO, and N2O. We analyze the role of such defects in fixed charge accumulation, electron trapping, and in the growth of the interface SiO2 layer. We find that nitrogen anneal of the oxides leads to an effective immobilization of native defects such as oxygen vacancies and interstitial oxygen ions, which may inhibit the growth of a silica layer. However, nitrogen in any form is unlikely to significantly reduce the fixed charge in the dielectric.

Details

Original languageEnglish
Article number053704
Pages (from-to)1-13
JournalJournal of Applied Physics
Volume97
Issue number5
Publication statusPublished - 2005
MoE publication typeA1 Journal article-refereed

    Research areas

  • High k, Modelling

ID: 3603881