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621.315.61(043);535.343;543.428.2 Dysprosium silicate films, Dy x Si y O z , have been investigated using infrared (IR) and Auger spectroscopy. The films have been formed by oxidizing dysprosium metal films on 5.2-nm-thick silicon dioxide films at a temperature of 600 o C. It is shown that the composition of the Dy x Si y O z dysprosium silicate films is close to that of dysprosium pyrosilicate, Dy 2 Si 2 O 7 , and irregular in thickness. On going from the film outer surface to the silicon substrate, the amount of dysprosium decreases and that of silicon bound to oxygen increases. Silicon dioxide, SiO 2 , predominates in the layer composition near the silicon substrate. The dielectric leakage current density in the accumulation mode is one order of magnitude lower in the Dy x Si y O z films than in the SiO 2 films of the same equivalent thickness due to the larger physical thickness of the former.Introduction. Silicon dioxide (SiO 2 ) films prepared by high-temperature oxidation of silicon and the SiO 2 -Si system are the basic components of transistors with the metal-oxide-semiconductor (MOS) structure in ultra-large-scale integrated (ULSI) circuits. However, the continuing miniaturization of ULSI MOS devices requires a constant decrease of the SiO 2 film thickness. One of the principal limitations to decreasing the thickness of SiO 2 films is the exponential increase of leakage current through the oxide because of an increase of the direct tunneling current. A promising new direction in the improvement of ULSI MOS devices is the use of dielectrics with a high dielectric permittivity (ε > 3.9) instead of SiO 2 as the dielectric gate [1]. Films of such dielectrics are thicker. However, their dielectric properties in the MOS structure are equivalent to SiO 2 films ≤5 nm thick. Among dielectrics with high dielectric permittivity, films of rare-earth metal (yttrium, lanthanum, dysprosium) oxides and silicates are under investigation [1-6]. The principal advantage of metal silicate films is their amorphous state up to significantly higher temperatures (~900

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