Damascene Benchmark of Ru, Co and Cu in Scaled Dimensions

Veen, Marleen H. van der; Heyler, N.; Pedreira, O. Varela; Ciofi, Ivan; Decoster, Stefan; Gonzalez, V. Vega; Jourdan, N.; Struyf, Herbert; Croes, Kristof; Wilson, Christopher J.; Tőkei, Zs.

doi:10.1109/iitc.2018.8430407

Cited by 46 publications

(25 citation statements)

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“…The Ru lines are 7 μm long and the dielectric is SiO 2 , and other details are listed in Table I. The cobalt lines studied in this article are fabricated using a damascene vehicle [20] with a low-k dielectric and are 22-nm-wide with an AR 2 and 100 μm long. Fig.…”

Section: A Sample Descriptionmentioning

confidence: 99%

Electromigration Activation Energies in Alternative Metal Interconnects

Beyne

Pedreira

Oprins

et al. 2019

IEEE Trans. Electron Devices

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The electromigration (EM) activation energy (E A ) of alternative metals, such as Ru and Co, was obtained using low-frequency noise (LFN) measurements. High activation energies were expected, but values of ≈1 eV are found, most likely related to diffusion along with the metaldielectric interface. Wafer-level accelerated EM tests were carried out to compare the LFN E A to the EM E A in the Ru wires. The calculation of the EM E A is found to be strongly dependent on the assumed temperature profile in the wire due to Joule heating (JH). The temperature profile was calculated analytically, assuming the contacts are at ambient temperature. For a void forming in direct proximity of the contact, the EM E A then matches the LFN E A . For a void at average wire temperature (ambient + JH), E A ≈ 2 eV. In addition to demonstrating the application of LFN to study EM in alternative metals, this article also cautions for the impact of JH on the calculation of E A in interconnects.

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Section: A Sample Descriptionmentioning

confidence: 99%

Electromigration Activation Energies in Alternative Metal Interconnects

Beyne

Pedreira

Oprins

et al. 2019

IEEE Trans. Electron Devices

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“…Co is a promising metal to replace W and/or Cu for narrow interconnect lines. [38][39][40][41] It has some processing advantages over W including benign CVD precursors, deposition without highresistivity nucleation layers, and grain growth through annealing. 19 The theoretically predicted ρo×λ products for Co in the basal plane and along the z-axis of its hexagonal structure are 7.31×10 -16 and 4.82×10 -16 Ωm 2 , yielding corresponding mean free paths λ = 11.8 and 7.77 nm for a room temperature ρo = 6.2 µΩcm.…”

Section: Introductionmentioning

confidence: 99%

Resistivity scaling and electron surface scattering in epitaxial Co(0001) layers

Milosevic

Kerdsongpanya

McGahay

et al. 2019

Journal of Applied Physics

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In situ and ex situ transport measurements on epitaxial Co(0001)/Al2O3(0001) layers with thickness d = 7-300 nm are used to quantify the resistivity ρ scaling due to electron-surface scattering. Sputter deposition at 300 °C followed by in situ annealing at 500 °C leads to singlecrystal layers with smooth surfaces (< 1 nm roughness) and an epitaxial relationship: Co[0001]║Al2O3[0001] and Co[ 0 1 10 ]║Al2O3[ 0 2 11 ]. The measured ρ vs d data is well described by the classical expression by Fuchs and Sondheimer at both 295 and 77 K, yielding a temperatureindependent product of the bulk resistivity times the mean free path ρo×λ and an effective roomtemperature λ = 19.5 ± 1.0 nm. The resistivity increases by 9-24 % upon air exposure for layers with d ≤ 21 nm, indicating a transition from partially specular (p = 0.55 ± 0.05) to completely diffuse (p = 0) surface scattering during native oxide formation. The overall results suggest that Co exhibits a resistivity scaling that is comparable to W and approximately 2× smaller than that of Cu, and that the resistance of narrow Co lines can be reduced considerably by engineering the Co-liner interface to facilitate specular electron scattering.

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“…For Cu interconnects, an excess of 100 Ω of vertical via resistance can be expected for future technology nodes due to the presence of diffusion barriers and wetting layers [32,43]. Although we find that the binding of pure fcc Ru to oxide is more favorable than the liners we studied, a liner may still be required to promote growth of Ru depending on the deposition method and chemistry of the precursors [10,16,47]. It is therefore valuable to quantify the via resistance penalty due to the presence of an adhesion liner.…”

Section: Adhesion and Electrical Properties Of Linersmentioning

confidence: 77%

“…With continued pitch reduction, however, the use of Cu may not be sustainable not only due to the size effect [2][3][4][5], whereby metal resistivity dramatically increases as cross-sectional area decreases, but also because of electromigration concerns and the reduction of via and line volume occupied by the diffusion and wetting liners necessary for integration of Cu in the BEOL [6]. To overcome these challenges posed by the continued use of Cu, research has focused on identifying and evaluating alternative conductors for use in advanced interconnect nodes [7][8][9][10][11]. Among the many identified options, Ru has emerged as a promising candidate due not only to reduced impact of the size effect compared to Cu [12,13] but also because of its resilience to electromigration [11,14].…”

Section: Introductionmentioning

confidence: 99%

First-Principles Evaluation of fcc Ruthenium for its use in Advanced Interconnects

Philip¹,

Lanzillo²,

Gunst

et al. 2020

Phys. Rev. Applied

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As the semiconductor industry turns to alternate conductors to replace Cu for future interconnect nodes, much attention has been focused on evaluating the electrical performance of Ru. The typical hexagonal close-packed (hcp) phase has been extensively studied, but relatively little attention has been paid to the face-centered cubic (fcc) phase, which has been shown to nucleate in confined structures and may be present in tight-pitch interconnects. Using ab initio techniques, we benchmark the performance of fcc Ru. We find that the phonon-limited bulk resistivity of the fcc Ru is less than half of that of hcp Ru, a feature we trace back to the stronger electron-phonon coupling elements in hcp Ru that are geometrically inherited from the modified Fermi surface shape of the fcc crystal. Despite this benefit of the fcc phase, high grain boundary scattering results in increased resistivity compared to Cu-based interconnects with similar average grain size. We find, however, that the line resistance of fcc Ru is lower than that of Cu below 21 nm line width due to the conductor volume lost to adhesion and wetting liners. In addition to studying bulk transport properties, we evaluate the performance of adhesion liners for fcc Ru. We find that it is energetically more favorable for fcc Ru to bind directly to silicon dioxide than through conventional adhesion liners such as TaN and TiN. In the case that a thin liner is necessary for the Ru deposition technique, we find that the vertical resistance penalty of a liner for fcc Ru can be up to eight times lower than that calculated for conventional liners used for Cu interconnects. Our calculations, therefore, suggest that the formation of the fcc phase of Ru may be a beneficial for advanced, low-resistance interconnects. arXiv:2001.02216v3 [cond-mat.mtrl-sci] a) fcc b) hcp

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Damascene Benchmark of Ru, Co and Cu in Scaled Dimensions

Cited by 46 publications

References 1 publication

Electromigration Activation Energies in Alternative Metal Interconnects

Electromigration Activation Energies in Alternative Metal Interconnects

Resistivity scaling and electron surface scattering in epitaxial Co(0001) layers

First-Principles Evaluation of fcc Ruthenium for its use in Advanced Interconnects

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