Elsevier

Surface Science

Volume 554, Issue 1, 1 April 2004, Pages L75-L80
Surface Science

Surface Science Letters
Investigation of the chemical state of ultrathin Hf–Al–O films during high temperature annealing

https://doi.org/10.1016/j.susc.2004.01.058Get rights and content

Abstract

Al2O3 incorporated HfO2 films grown by atomic layer deposition (ALD) were investigated by high-resolution X-ray photoelectron spectroscopy (HRXPS). The core level energy state of a 15 Å thick film showed a shift to higher binding energy, as the result of a silicate formation and Al2O3 incorporation. The incorporation of Al2O3 into the HfO2 film had no effect on silicate formation at the interface between the film and Si, while the ionic bonding characteristics and hybridization effects were enhanced compared to a pure HfO2 film. The dissociation of the film in an ultrahigh vacuum (UHV) is effectively suppressed compared to a pure HfO2 film, indicating an enhanced thermal stability of Hf–Al–O. Any dissociated Al2O3 on the film surface was completely removed into the vacuum by vacuum annealing treatment over 850 °C, while HfO2 contributed to Hf silicide formation on the film surface.

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Acknowledgements

This work was supported by the National Program for Tera-level Nanodevices of the Ministry of Science and Technology as one of the 21 century Frontier Programs.

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Cited by (19)

  • Interfacial thermal stability and band alignment of Al<inf>2</inf>O <inf>3</inf>/HfO<inf>2</inf>/Al<inf>2</inf>O<inf>3</inf>/Si gate stacks grown by atomic layer deposition

    2014, Journal of Alloys and Compounds
    Citation Excerpt :

    To investigate the effect of the annealing temperature on the conduction band offset of Al2O3/HfO2/Al2O3/Si gate stack, conduction band offset values as a function of annealing temperature for samples have been obtained. It was reported that annealing temperature not only changes the valence band offset of the film but also changes the conduction band offset of the film, that is because the electronic states would change due to the generation of phase separation, thus, change the band alignments of the film [6,32,33]. The conduction band offset can be obtained by simply subtracting the valence band offset and the energy gap of the Si substrate from the band gap of Al2O3/HfO2/Al2O3 film.

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