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

Kousseifi, M. El; Hoummada, K.; Épicier, Thierry; Mangelinck, Dominique

doi:10.1016/j.actamat.2015.07.062

Cited by 14 publications

(39 citation statements)

References 23 publications

(58 reference statements)

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“…Discussions based on interface energy are not straightforward, due to a lack on experimental data on the interface energy. More recently, Kousseifi et al[35] could quantitatively determine the interface energy for Pt-alloyed NiSi and θ-Ni 2 Si. However, different alloys, or different alloying concentration, can alter the preferential orientation of silicides or change the interface energy through accumulation at the grain-boundaries.…”

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confidence: 99%

Controlling the formation and stability of ultra-thin nickel silicides - An alloying strategy for preventing agglomeration

Geenen

Stiphout

Nanakoudis

et al. 2018

Journal of Applied Physics

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The electrical contact of the source and drain regions in state-of-the-art CMOS transistors is nowadays facilitated through NiSi, which is often alloyed with Pt in order to avoid morphological agglomeration of the silicide film. However, the solid-state reaction between as-deposited Ni and the Si substrate exhibits a peculiar change for as-deposited Ni films thinner than a critical thickness of t c =5 nm. Whereas thicker films form polycrystalline NiSi upon annealing above 450 • C, thinner films form epitaxial NiSi 2 films which exhibit a high resistance towards agglomeration. For industrial applications, it is therefore of utmost importance to assess the critical thickness with high certainty and find novel methodologies to either increase or decrease its value, depending on the aimed silicide formation. This paper investigates Ni films between 0 and 15 nm initial thickness by using of 'thickness gradients', which provide semi-continuous information on silicide formation and stability as a function of as-deposited layer thickness. The alloying of these Ni layers with 10 % Al, Co, Ge, Pd or Pt renders a significant change in the phase sequence as a function of thickness and dependent on the alloying element. The addition of these ternary impurities therefore change the critical thickness t c. The results are discussed in the framework of

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mentioning

confidence: 99%

Controlling the formation and stability of ultra-thin nickel silicides - An alloying strategy for preventing agglomeration

Geenen

Stiphout

Nanakoudis

et al. 2018

Journal of Applied Physics

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“…However, nucleation at the interface and/or at the triple junction, as well as the lateral growth along interface play an important role in the formation of silicide. This is particularly true for very thin films [47] and may lead to much more complex microstructures. Anyway, for thickness larger than about 10 nm, the nucleation and lateral growth end to a continuous layer which grows then essentially in a one-dimensional manner.…”

Section: Discussionmentioning

confidence: 99%

Reactive diffusion in the presence of a diffusion barrier: Experiment and model

Mangelinck

Luo

Girardeaux

2018

Journal of Applied Physics

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Reactions in thin film and diffusion barriers are important for applications such as protective coatings, electrical contact and interconnections. In this work the effect of a barrier on the kinetics of the formation for a single phase by reactive diffusion is investigated from both experimental and modeling point of view. Two types of diffusion barriers are studied: (i) a thin layer of W deposited between a Ni film and the Si substrate and (ii) Ni alloy films, Ni(1%W) and Ni(5%Pt), that form a diffusion barrier during the reaction with the Si substrate. The effect of the barriers on the kinetics of -Ni2Si formation is determined by in situ X ray diffraction and compared to models that explain the kinetics slowdown induced by both types of barrier. A linear parabolic growth is found for the deposited barrier with an increasing linear contribution for increasing barrier thickness. On the contrary, the growth is mainly parabolic for the barrier formed by reaction between an alloy film and the substrate. The permeability of the two types of barrier are determined and discussed. The developed models fit well with the dedicated model experiments, leading to a better understanding of the barrier effect on the reactive diffusion and allowing to predict the barrier behaviour in various applications.

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“…The TEM images (Fig. 7) allow a direct comparison with these models and the analytical solutions [61,63,67,68] have been used to fit the TEM images instead of the numerical simulation developed by Lucenko et al [11] and Vovk et al [9]. Moreover Fig.…”

Section: Lateral Growth: Comparison Between Models and Morphologies Dmentioning

confidence: 99%

“…The main assumptions of these models are: (1) the asymmetrical position of the NiSi particle with respect to the θ-Ni2Si /Si interface is due to the matter conservation and to the volume change during the reaction between θ-Ni2Si and Si, (2) the mechanical equilibrium of the interfacial energies is responsible for the particle shape (3) the Ni and Si interdiffusion along interfaces is assumed to drive the kinetics of the fast lateral growth; the elements Ni and Si are thus considered to diffuse in opposite directions along the Si/NiSi and θ-Ni2Si/NiSi interfaces, and (4) the driving force for the flux of the diffusing element along the interface is the gradient of the chemical potential difference due to the gradient of curvature. In these models [61,63,67,68], the steady state shape of the moving interface and its velocity are calculated from the flux and the mass conservation condition across the moving interface and the boundaries. In addition to reproduce the global shape of the precipitaes, the model developed by Pasichnyy and Gusak [63] allows the initial interface (θ-Ni2Si/Si) to be deformed and to become curved.…”

Section: Lateral Growth: Comparison Between Models and Morphologies Dmentioning

confidence: 99%

“…In addition to reproduce the global shape of the precipitaes, the model developed by Pasichnyy and Gusak [63] allows the initial interface (θ-Ni2Si/Si) to be deformed and to become curved. The assumptions of this model [63] are relatively similar to the one of El Kousseifi et al [67]: (1) asymmetrical position of the growing particle due to the matter conservation and to the volume change during the reaction, (2) mechanical equilibrium of the interfacial energies and (3) Ni and Si interdiffusion along interfaces with a Darken diffusion coefficient (D). However the diffusion is not driven by the gradient of curvature but by a gradient of concentration along the interface.…”

Section: Lateral Growth: Comparison Between Models and Morphologies Dmentioning

confidence: 99%

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Mechanisms of Silicide Formation by Reactive Diffusion in Thin Films

Mangelinck

2019

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Silicide formation by reactive diffusion is of interest in numerous applications especially for contact formation and interconnections in microelectronics. Several reviews have been published on this topic and the aim of this chapter is to provide an update of these reviews by focusing on new experiment results. This chapter presents thus some progress in the understanding of the main mechanisms (diffusion/reaction, nucleation, lateral growth…) for thin and very thin films (i.e. comprised between 4 and 50 nm). Recent experimental results on the mechanisms of formation of silicide are presented and compared to models and/or simulation in order to extract physical parameters that are relevant to reactive diffusion. These mechanisms include nucleation, lateral growth, diffusion/interface controlled growth, and the role of a diffusion barrier. The combination of several techniques including in situ techniques (XRD, XRR, XPS, DSC) and high resolution techniques (APT and TEM) is shown to be essential in order to gain understanding in the solid state reaction in thin films and to better control these reaction for making contacts in microelectronics devices or for other application.

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

Cited by 14 publications

References 23 publications

Controlling the formation and stability of ultra-thin nickel silicides - An alloying strategy for preventing agglomeration

Controlling the formation and stability of ultra-thin nickel silicides - An alloying strategy for preventing agglomeration

Reactive diffusion in the presence of a diffusion barrier: Experiment and model

Mechanisms of Silicide Formation by Reactive Diffusion in Thin Films

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