Electron Transport Across Cu/Ta(O)/Ru(O)/Cu Interfaces in Advanced Vertical Interconnects

Lanzillo, Nicholas A.; Briggs, Benjamin D.; Robison, Robert R.; Standaert, T.; Lavoie, C.

doi:10.1016/j.commatsci.2018.11.040

Cited by 12 publications

(11 citation statements)

References 35 publications

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“…Although oxidation typically results in a more resistive material, our results show that even if a TiN liner is fully oxidized to TiO, we should only expect an increase of resistance of about 3%. For the case where TaN is fully oxidized, forming TaO, we find that the via resistance is lowered by almost 10%, which follows the results seen in Cu liner calculations [32,43]. These results indicate the via resistance of Ru interconnects are less prone to degradation compared to Cu.…”

Section: Adhesion and Electrical Properties Of Linerssupporting

confidence: 83%

“…T (EF ) Area ( Å2 ) γ (10 As noted, the presence of an adhesion liner plays a critical role in determining BEOL parasitic RC delay since the resistance of interconnects depends not only on the bulk resistivity calculated in the previous section but also on the "vertical resistance" of current flow through vias that connect a given metal level to the one above or below it. 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].…”

Section: Structurementioning

confidence: 96%

“…The combination of Cu/TaN/Ru/Cu, a typical state-of-the-art BEOL liner and wetting layers stack, results in a vertical resistance of 122.3×10 −12 Ω-cm 2 [43], a specific resistivity that is over eight times that which we calculate for the TaO adhesion liner for fcc Ru. Even in the optimistic scenario without nitridation or oxidation, the stack of Cu/Ta/Ru/Cu results in a vertical resistance of 34.24 × 10 −12 Ω-cm 2 [32], which is still twice as resistive as a TaO Ru liner. Much of the vertical resistance seen in Cu vias can be attributed to the fact that both a diffusion barrier and a wetting layer are required for BEOL integration.…”

Section: Adhesion and Electrical Properties Of Linersmentioning

confidence: 97%

“…The conductance of the structure is proportional to the cross-sectional area of the device, so we report the areanormalized specific resistivity γ = A/G as is standard practice in the literature [18,20,22,23,31,32].…”

Section: Device Simulationsmentioning

confidence: 99%

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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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Section: Adhesion and Electrical Properties Of Linerssupporting

confidence: 83%

Section: Structurementioning

confidence: 96%

Section: Adhesion and Electrical Properties Of Linersmentioning

confidence: 97%

Section: Device Simulationsmentioning

confidence: 99%

See 2 more Smart Citations

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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“…A compromise is generally made, where the TaN thickness is as thin as possible such that electrical resistance is minimized but thick enough that pinholes (which can lead to copper diffusion and impact device yield through shorting) are not present. With the development of sub-5 nm technology nodes, the interconnect half-pitch will reach 20 nm and below, making even a few nanometers of a TaN layer a large portion of the cross-sectional area, with a significant impact on the resistivity between metal levelsa major performance limitation. − …”

Section: Introductionmentioning

confidence: 99%

Area-Selective Deposition of Tantalum Nitride with Polymerizable Monolayers: From Liquid to Vapor Phase Inhibitors

et al. 2022

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Area-selective depositions (ASDs) exploit surface reactivity differences to deposit a material on a desired growth surface. This chemically driven process produces a reflection of the prepattern, commonly, through the use of either atomic layer deposition (ALD) or chemical vapor deposition (CVD). The ASD of TaN may offer significant benefits in device fabrication. For instance, in silicon technologies, this offers the ability to lower the resistivity between metal interconnect levels and therefore to reduce stage delay (RC delay). However, the deposition of TaN thin films in an area-selective manner is challenging due to the temperature requirements for a high-quality ALD film, which may exceed the thermal stability of typical organic surface modifications. We report on the synthesis of an organic inhibitor that incorporates a thermal/photoreactive diyne moiety to enable cross-linking of the inhibitor film and subsequent use in a selective TaN process, which was maintained over a large process window, during the 300 °C TaN ALD process. On patterned substrates, up to 3.8 nm of a TaN film could be deposited on SiN or mesoporous SiCOH without detectable Ta amounts on either a Cu or W surface. The same concept of cross-linking the inhibiting layer was also applied to a reactive vapor-phase inhibitor, propargylamine, found to inhibit TaN, though with a narrower process window (on blanket films). On via patterns, this selective TaN process was achieved but exhibits a distinct tapered profile. The methods described demonstrate the compatibility of several reactive inhibitors to enable the selective deposition of TaN at an ALD temperature compatible with many device fabrication schemes.

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Surface sulfurization of liner and ruthenium metallization to reduce interface scattering for Low-Resistance interconnect

Chen,

Hsiao,

et al. 2024

Applied Surface Science

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Electron Transport Across Cu/Ta(O)/Ru(O)/Cu Interfaces in Advanced Vertical Interconnects

Cited by 12 publications

References 35 publications

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

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

Area-Selective Deposition of Tantalum Nitride with Polymerizable Monolayers: From Liquid to Vapor Phase Inhibitors

Surface sulfurization of liner and ruthenium metallization to reduce interface scattering for Low-Resistance interconnect

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