Formation of vanadium silicides by the interactions of V with bare and oxidized Si wafers

Abstract

Formation of vanadium silicides by the interactions of vanadium with bare and oxidized Si wafers has been studied by both x-ray diffraction and He ion backscattering techniques. X-ray diffraction was used to identify phases and ion backscattering to profile compositional changes. In the case of V on Si, the silicide VSi2, which is a silicon-rich phase, was found to form at temperatures from 600 to 1000 °C. In the case of V on SiO2, reactions took place only at temperatures above 800 °C, and the reaction products were identified to be V3Si, V5SI3, and V2O5. Both V3Si and V5Si3 are vandium-rich phases, and the V3Si that we found was a continuous layer between the substrate and the other two phases, and became superconducting at about 15 °K.

Kinetics of silicide formation by thin films of V on Si and SiO2 substrates

“…In contrast to Tu et al, 3 we observe a linear reaction rate for the silicide formation on Si, but oxygen is shown to decelerate the reaction noticeably. The resulting silicide layer has the composition VSi 2 • On Si0 2 substrates, the growth rate of the silicide layer is proportional to (time)…”

“…We have measured the rate of growth of the intermediate V 3 Si layer (b) as a function of anneal time at various temperatures. The result is given in Fig.…”

“…It is now known that films of silicide-forming transition metals react with a Si substrate and form the thermodynamically stable Sirich compound at temperatures which are typically onehalf of the melting point of the compound temperature. The kinetics of these reactions has been studied so far for Pd and Cr, 1 Hf, 2 and V. 3 The formation of Pd 2 Si, HfSi, and VSi 2 is reported to follow a (time) 1 / 2 dependence, while CrSi 2 forms linearly with time.…”

Thermodynamic properties of vanadium silicides. I. Standard molar enthalpy of formationΔfHmoof vanadium disilicide (VSi2) at the temperature 298.15 K

“…According to the phase diagram, (1) there are four distinct solid compounds in (vanadium + silicon); namely, V 3 Si, V 5 Si 3 , V 6 Si 5 , and VSi 2 . Only V 3 Si has a significant range of composition, and V 6 Si 5 appears to be stable only at elevated temperatures.…”

1481. Analysis of thin-film structures with nuclear backscattering and x-ray diffraction

“…It has recently been found that silicide layers are formed during heat treatment of metal layers on Si02. 11 • 16 Usually, a different phase is formed and the reaction temperature is 100-200°C higher than for the metal-silicon systems.…”