Nucleation and lateral growth during reactive diffusion in thin film of Ni silicide alloyed with Pt

In solid state reactions, the formation of a single product phase has been shown to occur in several steps. The first steps are the nucleation and the lateral growth. The following step is the thickening of the product by growth perpendicular to the interface plane. Several models were developed to model the lateral growth but experimental observations are scarce. Similarly, silicides can be obtained by solid state reaction between metal thin film and the Si substrate. Moreover, the Ni monosilicide alloyed with Pt is widely used as contacts in microelectronics and the fundamental mechanisms related to their formation, especially the nucleation and lateral growth, are of great interest for the applications.

In this work, the first steps of silicides formation between 10 nm Ni(10%Pt) alloy film and Si(100) have been studied by in situ-XRD annealing coupled with atom probe tomography (APT) and transmission electron microscopy (TEM). The composition of the interface was found to change the formation of the first phase and to lead either to d-Ni₂Si or q-Ni₂Si. The lateral growth of NiSi at the epitaxial θ-Ni₂Si/Si interface was evidenced by APT and TEM. The experimental shape of isolated NiSi precipitates resulting from the lateral growth of NiSi at the θ-Ni₂Si/Si interface are confronted to several models.

Financial support from the French CNRS (FR3507) and CEA METSA network (www.metsa.fr) is acknowledged.