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

• Published in: Surface science 2004-04, Vol.554 (1), p.L75-L80
• Main Authors: Cho, M.-H., Chang, H.S., Cho, Y.J., Moon, D.W., Min, K.-H., Sinclair, R., Kang, S.K., Ko, D.-H., Lee, J.H., Gu, J.H., Lee, N.I.
• Format: Article
• Language: English
• Subjects: Condensed matter: electronic structure, electrical, magnetic, and optical properties; Electron and ion emission by liquids and solids; impact phenomena; Exact sciences and technology; Interfaces, heterostructures, nanostructures; Photoelectron spectroscopy; Photoemission and photoelectron spectra; Physics; Semiconductor–insulator interfaces
• ISSN: 0039-6028; 1879-2758
• DOI: 10.1016/j.susc.2004.01.058

Al 2O 3 incorporated HfO 2 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 Al 2O 3 incorporation. The incorporation of Al 2O 3 into the HfO 2 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 HfO 2 film. The dissociation of the film in an ultrahigh vacuum (UHV) is effectively suppressed compared to a pure HfO 2 film, indicating an enhanced thermal stability of Hf–Al–O. Any dissociated Al 2O 3 on the film surface was completely removed into the vacuum by vacuum annealing treatment over 850 °C, while HfO 2 contributed to Hf silicide formation on the film surface.