Ru passivated and Ru doped ε-TaN surfaces as a combined barrier and liner material for copper interconnects: a first principles study

Natarajan, Suresh Kondati; Nies, Cara-Lena; Nolan, Michael

doi:10.1039/c8tc06118a

Cited by 15 publications

(33 citation statements)

References 51 publications

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“…[52] The descriptions of bulk epsilon-TaN, the low energy (1 1 0) surface, and Ru doped and passivated TaN have been published previously and the VASP files are available on https://github.com/MMDgroup/VASP. [9,39] We find that all of the TaN surfaces studied are metallic. To prepare our combined liner/barrier system, we doped with Ru onto Ta sites in the top layer of the surface and not throughout the slab; such a composition can be achieved using atomic layer deposition of TaN and then using a Ru precursor instead of the Ta precursor for the top layer.…”

Section: Methodsmentioning

confidence: 75%

“…This matches our previous understanding of Ru dopants acting as nucleation sites in the surface. [39] The transition from the surface to the S+2 layer (e2 in Figure 2(c)) shows a strong increase in the activation energy compared to the bare surface. This is caused by the incorporation of the migrating atom into one of the surface gaps at the start of the migration, which is shown in Figure 8 and is an important mechanism for the stabilisation of 2D copper on Ru-modified TaN.…”

Section: Study Of Growth Mechanism Of Cu Thin Filmmentioning

confidence: 97%

“…Next, we consider how our copper model interfaces with 1 ML Ru passivation of TaN. From our previous studies on adsorbates with 1 -4 copper atoms [9,39] , we know that Ru-passivation increases the strength of binding of Cu compared to Cu binding on TaN and that Cu atoms prefer to remain separated rather than associating. This is confirmed during the relaxation of a 2D Cu29, in which there is no migration of copper from the surface layer to the S+1 layer and copper remains flat while rearranging to conform to the corrugated Ru-passivated surface.…”

Section: Structure Of Copper On Bare Tan and 1 Monolayer Ru Passivated Tanmentioning

confidence: 99%

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Control of Cu morphology on Ru-passivated and Ru-doped TaN Surfaces – promoting growth of 2D conducting copper for CMOS interconnects

Nies

Natarajan²,

Nolan

2021

Preprint

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Prolonging the lifetime of Cu as level 1 and level 2 interconnect metal in future nanoelectronic devices is a significant challenge as device dimensions continue to shrink and device structures become more complex. At nanoscale dimensions Cu has high resistivity which prevents it functioning as a conducting wire and prefers to form non-conducting 3D islands. Given that changing from Cu to an alternative metal is challenging, we are investigating new materials that combine properties of diffusion barriers and seed liners to reduce the thickness of this layer and to promote successful electroplating of Cu to facilitate the coating of high-aspect ratio interconnect vias and to allow for optimal electrical conductance.In this study we propose a new combined barrier/liner materials based on modifying the surface layer of TaN barrier through Ru incorporation. Simulating a model Cu29 structure at 0 K and through finite temperature ab initio molecular dynamics on these surfaces allows us to demonstrate how the Ru content can control copper wetting, adhesion and thermal stability properties. Activation energies for single atom migrations onto a nucleating island of Cu allow insight into the growth mechanism of a Cu thin-film. Using this understanding allows us to tailor the Ru content on TaN to control the final morphology of the Cu film.

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Section: Methodsmentioning

confidence: 75%

Section: Study Of Growth Mechanism Of Cu Thin Filmmentioning

confidence: 97%

Section: Structure Of Copper On Bare Tan and 1 Monolayer Ru Passivated Tanmentioning

confidence: 99%

See 1 more Smart Citation

Control of Cu morphology on Ru-passivated and Ru-doped TaN Surfaces – promoting growth of 2D conducting copper for CMOS interconnects

Nies

Natarajan²,

Nolan

2021

Preprint

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“…The presence of droplets and dewetting phenomena are not only observed in aqueous and organic systems, but also in inorganic systems, such as liquid metals [ 5 ] and ultrathin layers [ 6 ]. The formation of metallic nanodroplets can be beneficial when intentionally used (e.g., to create strongly localized heat sources [ 7 – 8 ]), but it can also be disruptive (e.g., when ultrathin copper layers collapse on titanium nitride, damaging electronic devices [ 9 – 10 ]). However, in thin film applications these phenomena are rarely attributed to the dewetting process, since the name of the resulting structures are nanoparticles or clusters but rarely droplets.…”

Section: Introductionmentioning

confidence: 99%

Analysis of catalyst surface wetting: the early stage of epitaxial germanium nanowire growth

Ernst

Lange

Uebel

et al. 2020

Beilstein J. Nanotechnol.

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The dewetting process is crucial for several applications in nanotechnology. Even though not all dewetting phenomena are fully understood yet, especially regarding metallic fluids, it is clear that the formation of nanometre-sized particles, droplets, and clusters as well as their movement are strongly linked to their wetting behaviour. For this reason, the thermodynamic stability of thin metal layers (0.1–100 nm) with respect to their free energy is examined here. The decisive factor for the theoretical considerations is the interfacial energy. In order to achieve a better understanding of the interfacial interactions, three different models for estimating the interfacial energy are presented here: (i) fully theoretical, (ii) empirical, and (iii) semi-empirical models. The formation of nanometre-sized gold particles on silicon and silicon oxide substrates is investigated in detail. In addition, the strengths and weaknesses of the three models are elucidated, the different substrates used are compared, and the possibility to further process the obtained particles as nanocatalysts is verified. The importance of a persistent thin communication wetting layer between the particles and its effects on particle size and number is also clarified here. In particular, the intrinsic reduction of the Laplace pressure of the system due to material re-evaporation and Ostwald ripening describes the theoretically predicted and experimentally obtained results. Thus, dewetting phenomena of thin metal layers can be used to manufacture nanostructured devices. From this point of view, the application of gold droplets as catalysts to grow germanium nanowires on different substrates is described.

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“…To explore how this surface can form, we have performed MD calculations at 600K for the interaction of NH radicals with the Co(001) surface, where Co atoms were deposited at a coverage of 3.03 Co/nm2 and the original surface NH species were eliminated as ammonia. Two coverages of NH radicals are explored, i.e.…”

mentioning

confidence: 99%

Self-limiting Nitrogen/Hydrogen Plasma Radical Chemistry in Plasma-Enhanced Atomic Layer Deposition of Cobalt

Liu

Zhang

et al. 2021

Preprint

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formation and desorption due to overall endothermic reactions. Instead, H radicals react with trench N species, contributed to H transfer at metal precursor pulse, to form NH. These trench N species cannot be eliminated completely on Co(100) surface, which will be the source of N impurities for the deposited Co thin films. At the post-plasma stage, the metal surface will be covered with NHx-terminations with plasma generated NH radicals, which is then ready for the next deposition cycle. Our results explain why ammonia or H2/N2 plasma, which produce NHx species are required to deposit Co thin films using Co metallocene precursors.

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Ru passivated and Ru doped ε-TaN surfaces as a combined barrier and liner material for copper interconnects: a first principles study

Abstract: A study of Cu adatoms on Ru passivated and Ru doped ε-TaN to highlight their potential barrier and liner properties for copper interconnects.

Cited by 15 publications

References 51 publications

Control of Cu morphology on Ru-passivated and Ru-doped TaN Surfaces – promoting growth of 2D conducting copper for CMOS interconnects

Control of Cu morphology on Ru-passivated and Ru-doped TaN Surfaces – promoting growth of 2D conducting copper for CMOS interconnects

Analysis of catalyst surface wetting: the early stage of epitaxial germanium nanowire growth

Self-limiting Nitrogen/Hydrogen Plasma Radical Chemistry in Plasma-Enhanced Atomic Layer Deposition of Cobalt

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