Large-Area, Single-Layer Molybdenum Disulfide Synthesized at BEOL Compatible Temperature as Cu Diffusion Barrier

Lo, Chi-Chun; Zhang, Kehao; Smith, Ryan; Shah, Ketan; Robinson, Joshua A.; Chen, Zhihong

doi:10.1109/led.2018.2827061

Cited by 28 publications

(34 citation statements)

References 19 publications

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“…The criteria for evaluating a new barrier/liner are listed in Figure d. Not until very recently, has a large‐area, transfer‐free, and BEOL‐compatible MoS 2 barrier been realized …”

Section: Test Results Of Liner and Diffusion Barrier Properties The mentioning

confidence: 99%

Enhancing Interconnect Reliability and Performance by Converting Tantalum to 2D Layered Tantalum Sulfide at Low Temperature

Catalano

Khosravi

et al. 2019

Advanced Materials

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The interconnect half‐pitch size will reach ≈20 nm in the coming sub‐5 nm technology node. Meanwhile, the TaN/Ta (barrier/liner) bilayer stack has to be >4 nm to ensure acceptable liner and diffusion barrier properties. Since TaN/Ta occupy a significant portion of the interconnect cross‐section and they are much more resistive than Cu, the effective conductance of an ultrascaled interconnect will be compromised by the thick bilayer. Therefore, 2D layered materials have been explored as diffusion barrier alternatives. However, many of the proposed 2D barriers are prepared at too high temperatures to be compatible with the back‐end‐of‐line (BEOL) technology. In addition, as important as the diffusion barrier properties, the liner properties of 2D materials must be evaluated, which has not yet been pursued. Here, a 2D layered tantalum sulfide (TaSx ) with ≈1.5 nm thickness is developed to replace the conventional TaN/Ta bilayer. The TaSx ultrathin film is industry‐friendly, BEOL‐compatible, and can be directly prepared on dielectrics. The results show superior barrier/liner properties of TaSx compared to the TaN/Ta bilayer. This single‐stack material, serving as both a liner and a barrier, will enable continued scaling of interconnects beyond 5 nm node.

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“…The criteria for evaluating a new barrier/liner are listed in Figure d. Not until very recently, has a large‐area, transfer‐free, and BEOL‐compatible MoS 2 barrier been realized …”

Section: Test Results Of Liner and Diffusion Barrier Properties The mentioning

confidence: 99%

Enhancing Interconnect Reliability and Performance by Converting Tantalum to 2D Layered Tantalum Sulfide at Low Temperature

Catalano

Khosravi

et al. 2019

Advanced Materials

Self Cite

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“…These include catalysis [2,3], photonics [4,5], batteries [6], sensors [7,8] and semiconductors and electronics [9][10][11]. More recently, 2D materials have been explored as copper diffusion barriers in CMOS interconnect structures [12][13][14][15]. Furthermore, to enable the use of 2D materials in technology applications, processes have been developed to grow 2D materials via chemical vapour deposition (CVD) [16,17] and atomic layer deposition (ALD) [18,19].…”

Section: Introductionmentioning

confidence: 99%

“…In this study we aim to fill the gap in the literature between the adsorption of single Cu atoms and the adsorption of larger structures from the publications discussed above. We choose the Cu-MoS 2 ML system due to its potential significance for the electronics industry as a copper diffusion barrier [12][13][14][15]. Studying small Cu n (n = 1-4) structures allows us to investigate the first stages in the nucleation of a Cu film on MoS 2 monolayers, as well as the fundamental copper-TMD interactions, and thus gain significant insights into the range of stable configurations for Cu adsorption on MoS 2 .…”

Section: Introductionmentioning

confidence: 99%

DFT calculations of the structure and stability of copper clusters on MoS₂

Nies

Nolan

2020

Beilstein J. Nanotechnol.

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Layered materials, such as MoS2, are being intensely studied due to their interesting properties and wide variety of potential applications. These materials are also interesting as supports for low-dimensional metals for catalysis, while recent work has shown increased interest in using 2D materials in the electronics industry as a Cu diffusion barrier in semiconductor device interconnects. The interaction between different metal structures and MoS2 monolayers is therefore of significant importance and first-principles simulations can probe aspects of this interaction not easily accessible to experiment. Previous theoretical studies have focused particularly on the adsorption of a range of metallic elements, including first-row transition metals, as well as Ag and Au. However, most studies have examined single-atom adsorption or adsorbed nanoparticles of noble metals. This means there is a knowledge gap in terms of thin film nucleation on 2D materials. To begin addressing this issue, we present in this paper a first-principles density functional theory (DFT) study of the adsorption of small Cu n (n = 1–4) structures on 2D MoS2 as a model system. We find on a perfect MoS2 monolayer that a single Cu atom prefers an adsorption site above the Mo atom. With increasing nanocluster size the nanocluster binds more strongly when Cu atoms adsorb atop the S atoms. Stability is driven by the number of Cu–Cu interactions and the distance between adsorption sites, with no obvious preference towards 2D or 3D structures. The introduction of a single S vacancy in the monolayer enhances the copper binding energy, although some Cu n nanoclusters are actually unstable. The effect of the vacancy is localised around the vacancy site. Finally, on both the pristine and the defective MoS2 monolayer, the density-of-states analysis shows that the adsorption of Cu introduces new electronic states as a result of partial Cu oxidation, but the metallic character of Cu nanoclusters is preserved.

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“…[1] These include catalysis [2,3], photonics [4,5], batteries [6], sensors [7,8], semiconductors and electronics [9,10,11]. More recently 2D materials have been explored as copper diffusion barriers in CMOS interconnect structures [12,13,14,15].…”

Section: Introductionmentioning

confidence: 99%

“…We choose the Cu-MoS 2 ML system due to its potential significance for the electronics industry as a copper diffusion barrier. [12,13,14,15] Studying small Cu n structures, where n = 1-4, allows us to investigate the first stages in the nucleation of a Cu film on MoS 2 monolayers, as well as the fundamental copper-TMD interactions, and thus gain significant insights into the range of stable configurations for Cu adsorption on MoS 2 .…”

Section: Introductionmentioning

confidence: 99%

Structure and Stability of Cu_n Clusters (n = 1-4) Adsorbed on Stoichiometric and Defective 2D MoS₂

Nies¹,

Nolan²

2020

Meet. Abstr.

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Layered materials, such as MoS2, are being intensely studied due to their interesting properties and wide variety of potential applications. These materials are also interesting as supports for low dimensional metals for catalysis, while recent work has shown increased interest in using 2D materials in the electronics industry as a Cu diffusion barrier in semiconductor device interconnects. The interaction between different metal structures and MoS2 monolayers is therefore of significant importance and first principle simulations can probe aspects of this interaction not easily accessible to experiment. Previous theoretical studies have focused particularly on the adsorption of a range of metallic elements, including first row transition metals, as well as Ag and Au. However, most studies have examined single atom adsorption or adsorb nanoparticles of noble metals. This means there is a knowledge gap in terms of thin film nucleation on 2D materials. To begin addressing this issue, we present in this paper a first principles density functional theory (DFT) study of the adsorption of small Cu_n structures, where n = 1-4, on 2D MoS2 as a model system. We find on a perfect MoS2 monolayer that a single Cu atom prefers an adsorption site above the Mo atom. With increasing nanocluster size the nanocluster binds more strongly when Cu atoms adsorb atop the S atom. Stability is driven by the number of Cu-Cu interactions and the distance between adsorption sites, with no obvious preference towards 2D or 3D structures. The introduction of a single S vacancy in the monolayer enhances copper binding energy, although some Cu_n nanoclusters are actually unstable. The effect of the vacancy is localised around the vacancy site. Finally on both the pristine and defective MoS2 monolayer, the density of states analysis shows that the adsorption of Cu introduces new electronic states as a result of partial Cu oxidation, but the metallic character of Cu nanoclusters is preserved. File list (2) download file view on ChemRxiv Cu MoS2 Nies Preprint.pdf (4.06 MiB) download file view on ChemRxiv Cu MoS2 Nies SI.pdf (2.77 MiB) Structure and stability of Cu n clusters (n = 1-4) adsorbed on stoichiometric and defective 2D MoS 2

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Large-Area, Single-Layer Molybdenum Disulfide Synthesized at BEOL Compatible Temperature as Cu Diffusion Barrier

Cited by 28 publications

References 19 publications

Enhancing Interconnect Reliability and Performance by Converting Tantalum to 2D Layered Tantalum Sulfide at Low Temperature

Enhancing Interconnect Reliability and Performance by Converting Tantalum to 2D Layered Tantalum Sulfide at Low Temperature

DFT calculations of the structure and stability of copper clusters on MoS₂

Structure and Stability of Cu_n Clusters (n = 1-4) Adsorbed on Stoichiometric and Defective 2D MoS₂

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Large-Area, Single-Layer Molybdenum Disulfide Synthesized at BEOL Compatible Temperature as Cu Diffusion Barrier

Cited by 28 publications

References 19 publications

Enhancing Interconnect Reliability and Performance by Converting Tantalum to 2D Layered Tantalum Sulfide at Low Temperature

Enhancing Interconnect Reliability and Performance by Converting Tantalum to 2D Layered Tantalum Sulfide at Low Temperature

DFT calculations of the structure and stability of copper clusters on MoS2

Structure and Stability of Cun Clusters (n = 1-4) Adsorbed on Stoichiometric and Defective 2D MoS2

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DFT calculations of the structure and stability of copper clusters on MoS₂

Structure and Stability of Cu_n Clusters (n = 1-4) Adsorbed on Stoichiometric and Defective 2D MoS₂