Low Temperature Synthesis of Vertically Aligned Carbon Nanotubes with Electrical Contact to Metallic Substrates Enabled by Thermal Decomposition of the Carbon Feedstock

Nessim, Gilbert Daniel; Seita, Matteo; O’Brien, Kevin; Hart, A. John; Bonaparte, Ryan K.; Mitchell, Robert; Thompson, Carl V.

doi:10.1021/nl900675d

Cited by 146 publications

(147 citation statements)

References 41 publications

(60 reference statements)

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“…This translates to a resistance per tube (including internal tube resistance and contact resistances to support and probe tip) on the order of a few tens to a few hundreds of kX. Such values compare well to recent studies on CNT forest growth on conductive supports 11,27 and confirm our probe station result that the CNTs are highly conductive.…”

Section: Electrical Datasupporting

confidence: 90%

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In-situ study of growth of carbon nanotube forests on conductive CoSi2 support

Bayer

Zhang

Blume

et al. 2011

Journal of Applied Physics

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The growth of high density vertically aligned carbon nanotube forests on conductive CoSi2 substrate layers is characterized by in situ x-ray photoemission spectroscopy and x-ray diffraction. We use in situ silicidation to transform as loaded, low conductivity CoSi supports to highly conductive CoSi2 during nanotube growth. These cobalt silicide films are found to be stable against oxidation and carbide formation during growth and act as an excellent metallic support for growth of aligned nanotubes, resembling the growth on the insulating Fe/Al2O3 benchmark system. The good catalytic activity is attributed to interfacial reactions of the Fe catalyst particles with the underlying CoSi2 support. We obtain ohmic conduction from the support layer to the carbon nanotube forest.

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Section: Electrical Datasupporting

confidence: 90%

“…This application requires the CNTs to be grown by chemical vapor deposition (CVD) in very high density vertically-aligned forests. [4][5][6][7][8][9][10][11] There has been great progress in growing such forests on insulating substrates such as Al 2 O 3 or SiO 2 (Refs. [12][13][14][15][16][17][18][19][20][21].…”

mentioning

confidence: 99%

In-situ study of growth of carbon nanotube forests on conductive CoSi2 support

Bayer

Zhang

Blume

et al. 2011

Journal of Applied Physics

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“…11 Traditional thermal CVD methods are still good candidates for the lowtemperature growth of CNTs by using a gas preheating or a catalyst pretreatment etc. 12,13 However, the present growth rate of CNTs by thermal CVD is quite low and insufficient for the practical application of CNTs. Therefore, it is necessary to develop 2 highly efficient methods to grow high-quality CNTs at low temperature for the integration of CNTs into CMOS devices.…”

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confidence: 99%

High-rate low-temperature growth of vertically aligned carbon nanotubes

et al. 2010

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We report the high-rate and low-temperature growth of vertically aligned carbon nanotubes (CNTs) by a photo-thermal chemical vapour deposition (PTCVD) method using a Ti/Fe bi-layer film as the catalyst. The growth temperature is as low as 370 °C and the growth rate is up to 1.3 μm/min, at least 8 times faster than the reported values by traditional thermal CVD methods. Transmission electron microscopy observations reveal that as-grown CNTs are uniformly made of crystalline 5 − 6 graphene shells with an approximately 10 nm outer diameter and a 5 − 6 nm inner diameter. The low-temperature rapid growth of CNTs is strongly related with the unique top-down heating mode of PTCVD and the formation of Ti/Fe bimetallic solid solution. The present study will advance the deployment of CNTs as interconnects in nanoelectronics, through a CMOS-compatible low-temperature deposition method.

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“…19,20 Besides this work, the group of Awano, 10,13,18 incorporates a Cu line in conjunction with a BEOL compatible diffusion barriers.…”

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confidence: 99%

“…Using conductive atomic force microscopy (cAFM) and I-V characterization the electrical properties of the CNT vias were investigated as well as the impact of post-CNT growth procedures. Even though the cAFM technique was performed on vertically aligned CNTs before, 19,20 this is among the first reports comparing electrical characterization of fully integrated vias and cAFM measurements. 21 This comparison, in conjunction with Raman spectroscopy, provides a valuable method to examine the homogeneity and reliability of the CNT integration.…”

mentioning

confidence: 99%

Distinguishing between Individual Contributions to the Via Resistance in Carbon Nanotubes Based Interconnects

Fiedler

Toader

Hermann

et al. 2012

ECS J. Solid State Sci. Technol.

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We report on the design and fabrication of carbon nanotube (CNT) vias based on a hybrid metal/CNT technology. The CNTs were integrated on a 4 inch Si wafer platform using conventional semiconductor processes. Multiwalled carbon nanotubes were grown vertically aligned on a copper based metal line. Via holes were prepared using a single damascene process. By employing a substratebased selective deactivation of the catalyst, CNT growth was restricted to the vias. Following this process scheme, the impact of post-CNT growth procedures, like chemical mechanical planarization and sample annealing, were investigated and electrically evaluated using conductive atomic force microscopy and current-voltage (I-V) characterization. Probing 440 individual structures, the resistance of two series-connected 5 μm vias were determined to be (800 ± 60) after chemical mechanical planarization. By obtaining the I-V characteristics of single CNTs within an individual via, we found that the measured resistance is determined by the contact resistance of the CNT-metal interface. Two mechanisms were found to be relevant here. First partial oxidation of the metal interface during processing, and secondly, stress-induced voiding caused by the high temperatures during the CNT growth process. Changes in the integration scheme to reduce the overall CNT via resistance are proposed. Continuous down-scaling of the interconnect structures in ultralarge-scale-integrated electronic devices causes deterioration of the resistivity and reliability of copper lines. The International Technology Roadmap for Semiconductors (ITRS) proposed several emerging technologies to replace copper in future interconnect schemes.1 Among them, carbon nanotubes (CNT) are very promising due to their extraordinary electrical properties.2,3 Also the thermal properties of CNTs are highly beneficial for interconnect applications. Due to their one dimensional nature the thermal conduction is anisotropic with a longitudinal thermal conductivity, which can be as large as 6000 W/mK. [4][5][6] Furthermore, due to the strong sp 2 hybridized carbon bonds the CNTs exhibit an extraordinary mechanical strength leading to a large current carrying capacity, which can reach values three orders of magnitude higher than copper. [1][2][3] Currently research of CNT interconnects focuses on vias.7-18 Main challenges hereby are the compatibility with the Back-end-of-the-line (BEOL) technology requirement, 7 while simultaneously a high CNT quality and a large CNT density is required. 17 Various substrate materials for CNT growth are used by different groups. In recent reports the diffusion barrier TiN is used as conductive material. 11,12,15 Focussing on the application of CNTs for local interconnects, CNT based vias were prepared using Poly-Si as conductive substrate. 8Also CNT growth behavior on unstructured samples was investigated using Ta as substrate material, which is a typical liner material in BEOL. 19,20 Besides this work, the group of Awano, 10,13,18 incorporates a Cu line in conjunc...

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Low Temperature Synthesis of Vertically Aligned Carbon Nanotubes with Electrical Contact to Metallic Substrates Enabled by Thermal Decomposition of the Carbon Feedstock

Cited by 146 publications

References 41 publications

In-situ study of growth of carbon nanotube forests on conductive CoSi2 support

In-situ study of growth of carbon nanotube forests on conductive CoSi2 support

High-rate low-temperature growth of vertically aligned carbon nanotubes

Distinguishing between Individual Contributions to the Via Resistance in Carbon Nanotubes Based Interconnects

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