International Conference on Thin Film Deposition of Oxide Multilayers Hybrid Structures

J. Phys. IV France 11 (2001) Pr11-301-Pr11-305
DOI: 10.1051/jp4:20011149

XPS investigation of UV-annealed ultrathin Ta₂O₂ films on silicon

Q. Fang¹, J.Y. Zhang^{2, 3}, Z.M. Wang³, J.X. Wu³, B.J. O'Sullivan⁴, P.K. Hurley⁴, T.L. Leedham⁵, M.A. Audier⁶, J.P. Sénateur⁶ and I.W. Boyd<sup>2

1</sup>  Department of Electronic and Electrical Engineering, University College London, Torrington Place, London WCIE 7JE, U.K.
²  Department of Electronic and Electrical Engineering, University College London, Torrington Place, London WC1E 7JE, U. K.
³  Structure Research Laboratory, University of Science and Technology of China, Hefei 230026, China
⁴  National Microelectronics Research Centre, Lee Maltings, Prospect Row, Cork, Ireland
⁵  INORG-TECH, 25 James Carter Road, Mildenhall, Suffolk, Suffolk IP28 7DE, U.K
⁶  Institut National Polytechnique de Grenoble, École Nationale Supérieure de Physique de Grenoble, LMGP, BP. 46, 38402 Saint-Martin-d'Hères, France

Abstract
We report the use of UV lamp sources, providing high photon fluxes over large-areas, to initiate the photo-deposition of ultrathin tantalum pentoxide (Ta₂O₅) films with physical thickness between 4-10 nm at low temperatures (below 350°C). The photo-deposited film properties, deterrnined using various standard methods and electrical measurements, have shown that good quality films can be produced. We have found that although a thin sub-stoichiometric silicon oxide layer (SiO_x) was present at the Ta₂O₅/Si interface. The electrical properties of these tantalum oxide films are significantly improved following an UV annealing step in 1000 mbar of pure oxygen. XPS profiles revealed that the SiO_x layer could be transformed to SiO₂ after the UV annealing process. These XPS results are critically important for the understanding of the interface properties of the tantalum oxide films on Si in the quest to further improve the photo-CVD process.

© EDP Sciences 2001