Silicide formation with Pd-V alloys and bilayers

Abstract

Solid phase reactions in the temperature range between 250 and 600 °C between Si and V‐Pd bilayers as well as alloy layers have been studied by MeV ⁴He⁺ backscattering and x‐ray diffraction techniques. When a Pd layer is interposed between Si and V, the bilayer system starts to react at 2Si. Annealing at higher temperatures (∼600 °C) leads to a uniform layer of VSi₂ formed on top of the Pd₂Si. Reversing the bilayer sequence (Si/V/Pd) raises the reaction temperature of the system to ∼500 °C with V mixing into the Pd layer. Annealing at higher temperature leads to the formation and accumulation of Pd₂Si at the interface and a mixed (nonuniform) structure of Pd₂Si and VSi₂ in the outer surface region. For a Pd‐rich alloy (Pd₈₀V₂₀), a reaction started at about 300 °C and produced Pd₂Si by depleting Pd from the alloy. This resulted in a mixed structure of Pd₂Si and VSi₂ in the outer region, similar to the final stage of the Si/V/Pd system. For a V‐rich alloy (Pd₉₀V₁₀), the formation temperature of Pd₂Si is raised to ∼500 °C and again leads to a mixed structure. The amount of accumulation of Pd₂Si at the substrate‐silicide interface increases with the Pd content in the alloy.