Atomic Layer Deposited Co(W) Film as a Single-Layered Barrier/Liner for Next-Generation Cu-Interconnects

Shimizu, H.; Sakoda, Kaoru; Momose, Takeshi; Shimogaki, Yukihiro

doi:10.1143/jjap.51.05eb02

Cited by 43 publications

(32 citation statements)

References 45 publications

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“…This alternative‐to‐plasma and technically easier approach employs a filament that is heated up to a temperature in the range 1300–2000 °C to dissociate precursor molecules, for example, hydrogen or ammonia. Recently, this method has been successfully utilized for ALD of metals such as tungsten (W), nickel (Ni), and cobalt (Co) …”

Section: Introductionmentioning

confidence: 99%

Hot‐Wire Assisted ALD: A Study Powered by In Situ Spectroscopic Ellipsometry

Kovalgin

Yang

Banerjee

et al. 2017

Adv Materials Inter

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Hot‐wire assisted atomic layer deposition (HWALD) is a novel energy‐enhancement technique. HWALD enables formation of reactive species (radicals) at low substrate temperatures, without the generation of energetic ions and UV photons as by plasma. This approach employs a hot wire (tungsten filament) that is heated up to a temperature in the range of 1300–2000 °C to dissociate precursor molecules. HWALD has the potential to overcome certain limitations of plasma‐assisted processes. This work investigates the ability of a heated tungsten filament to catalytically crack molecular hydrogen or ammonia into atomic hydrogen and nitrogen‐containing radicals. The generation of these radicals and their successful delivery to the wafer (substrate) surface are experimentally confirmed by dedicated tellurium‐etching and silicon‐nitridation experiments. It further reports on deposition of low‐resistivity oxygen‐free tungsten films by using HWALD, as well as on the effect of hot‐wire‐generated nitrogen radicals and atomic hydrogen in deposition of aluminum nitride and boron nitride films. In parallel, this work provides important illustrative examples of using in situ real‐time monitoring of deposition and etching processes, together with extracting a variety of film properties, by spectroscopic ellipsometry technique.

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Section: Introductionmentioning

confidence: 99%

Hot‐Wire Assisted ALD: A Study Powered by In Situ Spectroscopic Ellipsometry

Kovalgin

Yang

Banerjee

et al. 2017

Adv Materials Inter

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“…As a matter of fact, publications related to HWALD are very rare in the literature. The few available works are on HWALD of Co(W) films , where ammonia gas is dissociated upon hot‐wire. Kostis et al introduced oxygen gas to oxidize hot tungsten filament and form volatile tungsten oxides.…”

Section: Introductionmentioning

confidence: 99%

Hot-wire assisted ALD of tungsten films:In-situstudy of the interplay between CVD, etching, and ALD modes

Yang

Aarnink

Kovalgin

et al. 2015

Phys. Status Solidi A

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In this work, we investigated an approach of hot‐wire assisted ALD (HWALD), utilizing a hot (up to 2000 °C) tungsten (W) wire. Tungsten films were deposited by this method using alternating pulses of WF6 gas and atomic hydrogen (at‐H). The latter was generated by catalytic dissociation of molecular hydrogen (H2) upon the hot‐wire. The W films were grown on a 100‐nm thick thermal SiO2. The growth process was monitored in real time by an in‐situ spectroscopic ellipsometer (SE). The real‐time SE monitoring revealed the coexistence of three processes: CVD, etching, and ALD of the W film. WF6 could back‐stream diffuse to the hot‐wire, resulting in WF6 decomposition and generation of a flux of fluorine (F). The latter caused etching of the grown W film and the filament, and provided extra tungsten supply, which might cause CVD. Higher pressure and higher carrier gas flow rate were found to largely suppress the back‐stream diffusion of WF6, which efficiently limited CVD. By controlling the dose of WF6 and process pressure, the etching had also been minimized. X‐ray photoelectron spectroscopy of optimized HWALD grown W revealed 99 at% of W; concentrations of oxygen and fluorine were lower than 1%, below the detection limit.

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“…1,3,5 Nevertheless, contamination of the adjacent dielectric materials from the plating bath is a concern, and much interest exists to develop alternative deposition methods. 10 Chemical vapor deposition (CVD) and atomic layer deposition (ALD) processes are of particular interest due to their ability to deposit ultrathin and conformal films and their potential application for surface selective deposition of barriers. 11,12 Previous work from Lim et al demonstrated the deposition of Cu, Ni, and Co transition metals on a variety of substrates from a series of chelating amidinate precursors under ALD and CVD conditions.…”

mentioning

confidence: 99%

“…The apparent transition from 2D to 3D growth may reflect preferential deposition at grains of a specific crystallographic orientation or reconciliation of heteroepitaxial strain between the Co, for which bulk films prepared below 420−450°C are generally hexagonal close packed (hcp), and Cu for which an fcc structure is more stable. 6,10,21,22 The crystalline structure of the Co is likely a mixture of fcc and hcp Co. X-ray diffraction studies revealed strong fcc (111) signals for blank Cu wafers and 4.5 nm Co/Cu film samples (Supporting Information). However, distinct hcp signals were indiscernible from the signal noise if present, and the Co contribution to the fcc signal is inseparable from the Cu contribution due to the magnitude of the signal.…”

mentioning

confidence: 99%

Atomic Interdiffusion and Diffusive Stabilization of Cobalt by Copper During Atomic Layer Deposition from Bis(N-tert-butyl-N′-ethylpropionamidinato) Cobalt(II)

Elko-Hansen

Ekerdt

2014

J. Phys. Chem. Lett.

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Electromigration of copper in integrated circuits leads to device failure. Potential solutions involve capping the copper with ultrathin cobalt films. We report the properties of cobalt films after deposition on polycrystalline Cu at 265 °C by atomic layer deposition from H2 and bis(N-tert-butyl-N'-ethylpropionamidinato) cobalt(II) (CoAMD). We find intermixing of Co and Cu producing a transition layer on the Cu nearly as thick as the Co-rich overlayer. X-ray photoelectron spectroscopy and time-of-flight secondary ion mass spectrometry depth profiling reveal that a finite amount of Cu continuously segregates to the progressing Co surface, minimizing the free surface energy, throughout deposition up to at least 16 nm. The Cu-stabilized Co film initially follows 2D growth and strain-relieving 3D crystal formation is apparent beyond 2 nm of film growth. Depth profiling indicates that Cu likely diffuses within the Co film and along the polycrystalline Co grain boundaries.

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Atomic Layer Deposited Co(W) Film as a Single-Layered Barrier/Liner for Next-Generation Cu-Interconnects

Cited by 43 publications

References 45 publications

Hot‐Wire Assisted ALD: A Study Powered by In Situ Spectroscopic Ellipsometry

Hot‐Wire Assisted ALD: A Study Powered by In Situ Spectroscopic Ellipsometry

Hot-wire assisted ALD of tungsten films:In-situstudy of the interplay between CVD, etching, and ALD modes

Atomic Interdiffusion and Diffusive Stabilization of Cobalt by Copper During Atomic Layer Deposition from Bis(N-tert-butyl-N′-ethylpropionamidinato) Cobalt(II)

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