Pt redistribution in N-MOS transistors during Ni salicide process

Atom probe tomography was used to study the redistribution of platinum during Ni(10 at.%Pt) silicidation of n-doped polycrystalline Si. These measurements were performed after the two annealing steps of standard salicide process both on a field-effect transistor and on unpatterned region submitted to the same process. Very similar results are obtained in unpatterned region and in transistor gate contact. The first phase to form is not the expected δ-Ni2Si but the non stoichiometric θ-Ni2Si. Pt redistribution is strongly influenced by this phase and the final distribution is different from what is reported in literature.

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► We analyzed by APT the Pt distribution in Ni(Pt)Si silicide contact of a 30 nm transistor and of a 330 μm test zone.
► We found the same Pt distribution in transistor gate and test zone: it excludes confinement effect in the transistor gate.
► The first phase to form during silicidation is not the expected δ-Ni2Si but the metastable θ-Ni2Si.
► The change in phase sequence leads to a different Pt distribution and promotes high Pt incorporation in Ni(Pt)Si.