IUVSTA 15th International Vacuum Congress (IVC-15), AVS 48th International Symposium (AVS-48), 11th International Conference on Solid Surfaces (ICSS-11)
    Dielectrics Tuesday Sessions
       Session DI-TuM

Paper DI-TuM5
Solid State Reactions in Hafnium Silicate Thin Films

Tuesday, October 30, 2001, 9:40 am, Room 130

Session: High K Dielectrics II
Presenter: P.F. Lyman, University of Wisconsin-Milwaukee
Authors: H.T. Johnson-Steigelman, University of Wisconsin-Milwaukee
A.V. Brinck, University of Wisconsin-Milwaukee
P.F. Lyman, University of Wisconsin-Milwaukee
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Oxides and silicates of hafnium are promising high-dielectric candidates for microelectronics applications because it seems likely that these materials will be stable at their interface with silicon@footnote 1@ due to the large heat of formation of Hf oxides. If hafnium oxides and silicates are indeed stable against reduction by Si at the dielectric/silicon interface, then, as a corollary, Hf metal should be able to reduce SiO@sub 2@. This supposition was tested by forming nm-thick films of hafnium silicates by solid state reaction of Hf metal films deposited on SiO@sub 2@ in ultrahigh vacuum. Charge transfer during the reaction was monitored by examining the binding energies of the Hf 4f and Si 2p core levels using x-ray photoelectron spectroscopy (XPS). As predicted, the Hf levels shifted to deeper binding energies upon annealing, while the Si core level corresponding to SiO@sub 2@ shifted to shallower binding energy. These shifts are consistent with charge being transferred from the Hf to the Si atoms, as would be expected for reduction of SiO@sub 2@ by Hf. Other aspects of the reaction between Hf, O, and Si were explored using thicker (µm) films. It is clear from these investigations that Hf metal can consume SiO@sub 2@ layers, with sometimes surprising results. @FootnoteText@ @footnote 1@ G.D. Wilk and R.M. Wallace, Appl. Phys. Lett. V.76, p.112 (2000)