First stage of CoSi2 formation during a solid-state reaction

Abstract

The kinetics of CoSi2 formation via a solid-state reaction between CoSi and single crystal Si has been the object of many studies in the past. Because of the importance of nucleation, complex kinetics has been reported. In this work, we investigate CoSi2 formation kinetics with in-situ diffraction during isothermal annealing of CoSi films on Si (100). In-situ measurements allow capturing the initial stage of CoSi2 formation. An initial t3/2 time-dependent evolution is observed and attributed to 3D growth of individual nuclei. This first regime is followed after the coalescence of the nuclei by a classical parabolic t1/2 one-dimensional film growth. We evidence a marked influence of the initial Co thickness (50 nm vs 10 nm) on the growth kinetics. A significant slowdown of the CoSi2 formation kinetics is observed for the thinnest film, whereas the activation energy remains the same. These results shine a new light on the complex formation kinetics of CoSi2 during solid-state reaction between CoSi and single crystal silicon and bring new knowledge about what occurs in the ultra-thin film regime, which is important for nanotechnologies.

Direct observation of NiSi lateral growth at the epitaxial θ-Ni2Si/Si(1 0 0) interface

“…These models are based on different approximations and different phenomena. However, all of the models consider the diffusion along the interfaces and they conclude that the product phase should reach a stationary thickness that depends on the kinetics parameters, in accordance with the experimental results [14][15][16][17]19]. The models also led to a relatively similar particle shape.…”

“…Several experimental studies [14][15][16][17][18][19] reported the presence of a discontinuous phase as the first results of the reaction between the two other phases. However, the entire particle shape has not been reported; thus, it is not possible to compare these experimental results with existing models [13,20,22,23].…”

“…Apart from DSC measurements, Lucadamo et al [18] presented evidence for a two-stage reaction mechanism in Nb/Al multilayer thin-films by TEM and in situ X-ray diffraction (XRD) experiments using high-intensity synchrotron radiation. Delattre et al also found CoSi 2 islands with irregular shapes at the CoSi/Si interface [19]. The Al 9 Co 2 phase was also identified [20] as the first reaction product using atom probe tomography (APT): instead of a continuous layer, globular nuclei were observed at the beginning of the Al/Co reaction, and they quickly grew to a thickness of approximately et al [21] found a Ni 2 Si particle with a shape in accordance with nucleation followed by lateral growth formation after the deposition of a Ni film on a Si substrate.…”

“…The Al 9 Co 2 phase was also identified [20] as the first reaction product using atom probe tomography (APT): instead of a continuous layer, globular nuclei were observed at the beginning of the Al/Co reaction, and they quickly grew to a thickness of approximately et al [21] found a Ni 2 Si particle with a shape in accordance with nucleation followed by lateral growth formation after the deposition of a Ni film on a Si substrate. However, in both cases [19,20], the limitation of the APT field view does not allow the total particle to be analyzed.…”

Mechanisms of Silicide Formation by Reactive Diffusion in Thin Films

“…Using transmission electron microscopy (TEM) and in situ X-ray diffraction (XRD) experiments with high-intensity synchrotron radiation, Lucadamo et al [56] evidenced a two-stage reaction mechanism in Nb/Al multilayer thinfilms. Delattre et al found CoSi2 precipitates at the CoSi/Si interface by TEM [58] . Precipitates of Al9Co2 that quickly grow to form a dense layer were observed by atom probe tomography (APT) as the first product of the Al/Co reaction [59].…”