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

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Journal Title
Journal ISSN
Volume Title
School of Science | A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
Date
2005
Major/Subject
Mcode
Degree programme
Language
en
Pages
053704/1-13
Series
Journal of Applied Physics, Volume 97, Issue 5
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.
Description
Keywords
high k, modelling, nitrogen, postdeposition anneal, hafnia, electric properties
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Citation
Gavartin, J. L. & Shluger, A. L. & Foster, Adam S. & Bersuker, G. I. 2005. The role of nitrogen-related defects in high-k dielectric oxides: Density-functional studies. Journal of Applied Physics. Volume 97, Issue 5. 053704/1-13. ISSN 0021-8979 (printed). DOI: 10.1063/1.1854210