Formation of ultrathin Ni germanides: solid-phase reaction, morphology and texture

Stiphout, K. van; Geenen, Filip; Schutter, Bob De; Santos, Nuno M.; Miranda, S. M. C.; Joly, Vincent; Detavernier, Christophe; Pereira, L. M. C.; Temst, Kristiaan; Vantomme, André

doi:10.1088/1361-6463/aa8cad

Cited by 6 publications

(3 citation statements)

References 38 publications

(125 reference statements)

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“…Metal germanides are the most logical option, being equivalent to TiSi 2 , CoSi 2 , and NiSi employed in Si devices. , Owing to its low resistivity, nickel germanide is one of the most prominent candidates for contacting Ge. Ni x Ge y films are typically prepared by annealing physical vapor-deposited (PVD) Ni metal films on Ge substrates. − Atomic layer deposition (ALD) provides superior accuracy and conformality to the PVD techniques and thus enables scaling down with three-dimensional (3D) designs and sub-10 nm thin films. − There are no reports of processes involving direct ALD of metal germanides. The ALD route to NiGe has previously been realized only by heating ALD Ni or NiO films on Ge to temperatures above 400 °C. , …”

Section: Introductionmentioning

confidence: 99%

Nickel Germanide Thin Films by Atomic Layer Deposition

et al. 2019

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This work presents preparation of nickel germanide (Ni 2 Ge) thin films by atomic layer deposition (ALD). The films were grown using NiCl 2 (tmpda) (tmpda = N,N,N′,N′,-tetramethyl-1,3-propanediamine) and tributylgermanium hydride serving as a new, efficient reducing agent. This is the first time ALD Ni x Ge y films are prepared directly upon the combination of two precursors and without any annealing treatment. Ni x Ge y is an important contact material for enabling Ge-based transistors and thus circumventing the scaling issues related to current microelectronics. The Ni 2 Ge process was examined at low temperatures of 160−200 °C. Self-limiting, saturative growth with a high growth rate of 0.91 Å/cycle was observed at 180 °C. The films were thoroughly analyzed in terms of morphology, crystallinity, composition, and resistivity. The Ni 2 Ge films were pure, with the sum of contaminants being less than 1 at. %. Owing to their high purity, the films exhibited low resistivity, suggesting suitability for contact applications.

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Section: Introductionmentioning

confidence: 99%

Nickel Germanide Thin Films by Atomic Layer Deposition

et al. 2019

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“…Especially, such ultrathin NiGe films resulted from thin Ni films below 10 nm is more prone to agglomerating as predicted by thermodynamics. [26][27][28] How the introduction of carbon working for such ultrathin NiGe films is, therefore, of great interest in advanced Ge-based devices. In this work, the impact of carbon pre-germanidation implantation (PGI) on the thermal stability of NiGe films is systematically investigated while the initial deposited Ni films vary from 10 to 2 nm.…”

mentioning

confidence: 99%

Role of Carbon Pre-Germanidation Implantation on Enhancing the Thermal Stability of NiGe Films Below 10 nm Thickness

Liu¹,

Xu²,

Jin-biao³

et al. 2020

ECS J. Solid State Sci. Technol.

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The effects of carbon on improving the thermal stability of relatively thick NiGe films were manifested in previous work. How this thermal stability can be maintained for ultrathin NiGe films i.e. below 10 nm thickness, is, however, still unknown and deserves to be explored. In this work, the effects of carbon Pre-Germanidation Implantation (PGI) on the thermal stability of ultrathin NiGe films below 10 nm thickness were systematically studied. For different thicknesses of Ni layers, as-prepared NiGe films with carbon PGI were characterized by beans of sheet resistance measurement, X-ray diffraction (XRD), scanning electron microscopy (SEM) and secondary ion mass spectroscopy (SIMS). The presence of carbon is proved to be still effective in enhancing the thermal stability of ultrathin NiGe films by ∼200 °C compared to the counterparts without C. The homogeneously distributed C at NiGe grain boundaries and C peak at the NiGe/Ge interface is responsible for such a distinguished improved thermal stability.

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“…20 In the present study, the influence of adding Ta or W to the system of Ni and Ge prior to annealing is investigated. Tantalum and W have been selected because they do not form germanides below 700 and 900 °C, respectively.…”

mentioning

confidence: 99%

Improving the morphological stability of nickel germanide by tantalum and tungsten additions

Jablonka

Kubart

Gustavsson

et al. 2018

Applied Physics Letters

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To enhance the morphological stability of NiGe, a material of interest as a source drain-contact in Ge-based field effect transistors, Ta or W, is added as either an interlayer or a capping layer. The efficacy of this Ta or W addition is evaluated with pure NiGe as a reference. While interlayers increase the NiGe formation temperature, capping layers do not retard the NiGe formation. Regardless of the initial position of Ta or W, the morphological stability of NiGe against agglomeration can be improved by up to 100 °C. The improved thermal stability can be ascribed to an inhibited surface diffusion, owing to Ta or W being located on top of NiGe after annealing, as confirmed by means of transmission electron microscopy, Rutherford backscattering spectrometry, and atom probe tomography. The latter also shows a 0.3 at. % solubility of Ta in NiGe at 450 °C, while no such incorporation of W is detectable.

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Formation of ultrathin Ni germanides: solid-phase reaction, morphology and texture

Cited by 6 publications

References 38 publications

Nickel Germanide Thin Films by Atomic Layer Deposition

Nickel Germanide Thin Films by Atomic Layer Deposition

Role of Carbon Pre-Germanidation Implantation on Enhancing the Thermal Stability of NiGe Films Below 10 nm Thickness

Improving the morphological stability of nickel germanide by tantalum and tungsten additions

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