The Critical Role of pH Gradient Formation in Driving Superconformal Cobalt Deposition

Rigsby, Matthew A.; Brogan, Lee; Doubina, Natalia; Liu, Yihua; Opocensky, Edward C.; Spurlin, Tighe A.; Jian, Zhou; Reid, Jonathan D.

doi:10.1149/2.0211901jes

Cited by 32 publications

(34 citation statements)

References 37 publications

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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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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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“…Figure 1c schematically summarizes the electrochemical components of the overall surface process occurring during superconformal Co electroplating of patterned Si wafers. Speci cally, unlike CuED, CoED processes carried out from aqueous plating baths are unavoidably accompanied by the hydrogen evolution reaction (HER), thereby developing pH gradients adjacent to the surface of the patterned wafers as they proceed [37][38][39] . The reaction rate of these two components (CoED and HER) is expressed in Fig.…”

Section: Resultsmentioning

confidence: 99%

Operando laser scattering: probing the evolution of local pH gradients on complex electrode architectures

Grozovski¹,

Moreno‐García²,

Karst³

et al. 2021

Preprint

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Self-assembly, complexation, agglomeration and precipitation phenomena relevant to biological, electrocatalytic and technological processes are strongly influenced by changes of the local pH at the solid-liquid interfaces where they occur. Understanding proton dynamics in the diffusion layers generated by these processes is of prime importance to improve their diagnosis and enable modelling and better control over them. Here we introduce a non-invasive pH-sensing approach that is based on the Tyndall effect enhancement modulated by pH-controlled agglomeration events. Using metal electrodeposition for advanced semiconductor wiring technology as a test vehicle, we demonstrate that our proposed strategy simultaneously provides real-time visualization of the pH dynamics and pH-guided reactivity with high spatial resolution without physically or chemically influencing the investigated surfaces. We suggest that its applicability can be universally extended to other relevant nanoaggregation/decomplexation processes occurring at light-addressable interfaces provided the probed colloids are smaller than the wavelength of visible light.

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“…The relatively elevated pH at the base thermodynamically promotes the reduction of CoOH + , an intermediate in the Co-plating reaction, to enable super-filling (Figure 13d). [263] A few aspects must be improved in Co interconnects to prepare for future technology node interconnect scaling. Although the high cohesive energy of Co allows the reduction of barrier thickness, the TiN barrier for the Co line still exhibited a high resistivity.…”

Section: Cobaltmentioning

confidence: 99%

“…Reproduced with permission. [ 263 ] Copyright 2018, The Electrochemical Society. e) Schematic illustration of the reaction behavior of Co/CoTi x /SiO 2 according to the annealing temperature: as‐deposited (top), annealed at 500 °C (middle), and at 700 °C (bottom).…”

Section: Next‐generation Interconnect Materialsmentioning

confidence: 99%

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Materials Quest for Advanced Interconnect Metallization in Integrated Circuits

et al. 2023

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Integrated circuits (ICs) are challenged to deliver historically anticipated performance improvements while increasing the cost and complexity of the technology with each generation. Front‐end‐of‐line (FEOL) processes have provided various solutions to this predicament, whereas the back‐end‐of‐line (BEOL) processes have taken a step back. With continuous IC scaling, the speed of the entire chip has reached a point where its performance is determined by the performance of the interconnect that bridges billions of transistors and other devices. Consequently, the demand for advanced interconnect metallization rises again, and various aspects must be considered. This review explores the quest for new materials for successfully routing nanoscale interconnects. The challenges in the interconnect structures as physical dimensions shrink are first explored. Then, various problem‐solving options are considered based on the properties of materials. New materials are also introduced for barriers, such as 2D materials, self‐assembled molecular layers, high‐entropy alloys, and conductors, such as Co and Ru, intermetallic compounds, and MAX phases. The comprehensive discussion of each material includes state‐of‐the‐art studies ranging from the characteristics of materials by theoretical calculation to process applications to the current interconnect structures. This review intends to provide a materials‐based implementation strategy to bridge the gap between academia and industry.

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The Critical Role of pH Gradient Formation in Driving Superconformal Cobalt Deposition

Cited by 32 publications

References 37 publications

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

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

Operando laser scattering: probing the evolution of local pH gradients on complex electrode architectures

Materials Quest for Advanced Interconnect Metallization in Integrated Circuits

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