UV activated surface preparation of silicon for high-k dielectric deposition

Casey C. Finstad, Anthony J. Muscat

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

1 Scopus citations

Abstract

High-k gate materials, such as HfO2, are unstable on silicon and form low permittivity interfacial oxides when heated. A single layer of silicon nitride grown prior to gate dielectric deposition could serve as a diffusion barrier to prevent oxide formation. A monolayer film of surface amine groups will be chemically similar to surface hydroxyl groups, and could also serve as a seed layer to promote the nucleation of a high-k film. The deposition of amines (≡Si-NH2 or ≡Si-NH-Si≡) on chlorine and hydrogen terminated Si(100) at low temperature (<100°C) was investigated using x-ray photoelectron spectroscopy (XPS). UV-Cl2 exposures (0.1-10 Torr Cl2 at 25-150°C, 10-600 s, 1000 W Xe lamp) were used to terminate Si(100) with Cl atoms. Exposure to NH3 (0.1-1000 Torr, 75°C, 5-60 min) replaced Cl atoms with up to 0.3 ML of amine groups, as measured by XPS. Cl atoms served as reactive leaving groups, lowering the overall activation energy barrier for nitridation. Alternatively, UV photons with energy greater than 5.7 eV were used to photodissociate NH3 molecules, yielding NH2 photofragments that reacted with the H-terminated Si(100) surface. At a UV photon flux of 19 mW/cm2, the N coverage increased with time and saturated at ∼1 ML. Significant oxygen was observed on the surface due to H2O contamination in the source gas.

Original languageEnglish (US)
Title of host publicationUltra Clean Processing of Silicon Surfaces VII, UCPSS 2004 - Proceedings of the 7th International Symposium on Ultra Clean Processing of Silicon Surfaces (UCPSS)
PublisherTrans Tech Publications Ltd
Pages7-10
Number of pages4
ISBN (Print)390845106X, 9783908451068
StatePublished - Jan 1 2005
Event7th International Symposium on Ultra Clean Processing of Silicon Surfaces, UCPSS 2004 - Brussels, Belgium
Duration: Sep 20 2004Sep 22 2004

Publication series

NameSolid State Phenomena
Volume103-104
ISSN (Print)1012-0394

Other

Other7th International Symposium on Ultra Clean Processing of Silicon Surfaces, UCPSS 2004
CountryBelgium
CityBrussels
Period9/20/049/22/04

Keywords

  • Ammonia
  • Atomic layer deposition (ALD)
  • Chlorine
  • Diffusion barrier
  • Seed layer
  • Silicon nitride
  • Ultraviolet
  • XPS

ASJC Scopus subject areas

  • Atomic and Molecular Physics, and Optics
  • Materials Science(all)
  • Condensed Matter Physics

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  • Cite this

    Finstad, C. C., & Muscat, A. J. (2005). UV activated surface preparation of silicon for high-k dielectric deposition. In Ultra Clean Processing of Silicon Surfaces VII, UCPSS 2004 - Proceedings of the 7th International Symposium on Ultra Clean Processing of Silicon Surfaces (UCPSS) (pp. 7-10). (Solid State Phenomena; Vol. 103-104). Trans Tech Publications Ltd.