Properties of La-silicate high-K dielectric films formed by oxidation of La on silicon

Abstract

In this article, we present data on the properties of La-based high-k dielectric films prepared by oxidation of La deposited by physical vapor deposition on silicon. Films are characterized by x-ray photoelectron spectroscopy, infrared absorption, and capacitance versus voltage analysis. We find that when we oxidize La metal sputter deposited on Si substrates, it reacts with the silicon substrate to form La silicate. La films as thick as 300 Å will react completely with Si under moderate oxidation conditions (900 °C for 10 min) suggesting a very rapid silicidation reaction between La and Si. Under some processing conditions the as-deposited films contain a small La2O3 component that reduces to La silicate upon anneal at high temperatures. La-silicate films do not phase separate into La2O3 and SiO2 upon annealing at 1050 °C, and their resistance to H2O incorporation depends critically on the oxidation temperature. Electrical measurements show a high concentration of positive fixed charge.

Photoemission study of the SiO2 conversion mechanism to magnesium silicate

“…1 The formation of thermally and chemically stable metal-silicates at the silicon surface may prevent the growth of SiO 2 . Previous studies have shown that silicate layers can be formed by deposition of various metals including yttrium, 2 lanthanum, 3 and erbium, 4 and have been shown to produce promising electrical and physical characteristics. In this study the formation of a magnesium silicate interfacial layer is investigated as an alternative to SiO 2 due to its high reported thermal stability.…”

SrO capping effect for La2O3/Ce-silicate gate dielectrics

“…The similar behavior can be observed as a negative shift in La 3d 5/2 spectra. It has been reported that the binding energy of La 3d 5/2 spectrum shifts in positive direction due to silicate reaction [15]. Therefore, the negative shift in binding energy might be caused by the generation of La-O-Sr within the La-silicate layer.…”

The effect of Si surface nitridation on the interfacial structure and electrical properties of (La2O3)0.5(SiO2)0.5 high-k gate dielectric films

“…Among rare earth oxides, La 2 O 3 is attractive due to its highest dielectric constant, but it is chemically unstable, as lanthanum hydroxide and carbonate are formed with exposure to ambient atmosphere [13], resulting in the unwanted flatband voltage shifts. Therefore several recent studies report preferential formation of lanthanum silicate films to improve the electrical and structural stabilities of La 2 O 3 [13,14]. Although detrimental to the permittivity, they are more stable and less apt to contain oxygen deficiencies.…”