Diffusion barrier property of TaN between Si and Cu

Oku, Takeo; Kawakami, Eiji; Uekubo, Masaki; Kondo, Takahiro; Yamaguchi, S.; Murakami, Masanori

doi:10.1016/0169-4332(96)00464-3

Cited by 239 publications

(127 citation statements)

References 17 publications

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“…This observation is consistent with previous measurements on Cu 45 . A Kissinger analysis by repeating the RTA measurement at 3 different ramp rates yields Ea ~ 1.6 eV which is close to the value reported earlier 46 . Similar kinetics studies on CVD Ru (3nm)/ALD MN (x nm)/Si (M=Ti, Ta; x = 0, 0.5) film stacks yields Ea ~ 2.1 -2.3 eV which is consistent with previous measurements 37 .…”

Section: Kinetics Of Silicide Formation With and Without A Barriersupporting

confidence: 67%

Atomic layer deposited ultrathin metal nitride barrier layers for ruthenium interconnect applications

Dey

Yu²,

Consiglio³

et al. 2017

Journal of Vacuum Science &Amp; Technology A: Vacuum, Surfaces, and Films

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RC-time delay in Cu interconnects is becoming a significant factor requiring further performance improvements in future nanoelectronic devices. Choice of alternate interconnect materials, as for example, refractory metals, and subsequent integration with underlying barrier and liner layers are extremely challenging for the sub-10 nm nodes. The development of conformal deposition processes for alternate interconnects, liner, and barrier materials are crucial in order for implementation of a possible replacement for Cu interconnects for narrow line widths. In this study we report on ultra-thin (~ 3nm) chemical 2 vapor deposition (CVD) grown ruthenium films on 0.5 and 1 nm thick metal nitride (TiN, TaN) barrier layers deposited via atomic layer deposition (ALD). Using scanning electron microscopy, we determined the effect of the underlying barrier layer on the coverage of the ruthenium overlayer. We utilized synchrotron x-ray diffraction with in-situ rapid thermal annealing to investigate the thermal stability of the barrier layers and determine the effective activation energies of barrier failure leading to ruthenium monosilicide formation.For Ru films deposited directly on Si and on 0.5 nm MN (M=Ti, Ta) covered Si substrates, silicide formation proceeds via a two-step crystallization process involving lateral nucleation above ~ 440 °C followed by thickening of the ruthenium monosilicide layer above ~520 °C. This silicidation temperature of ~ 440 °C could be potentially problematic in back-end-of-the-line (BEOL) processing since it is close to the typical thermal budget used. However ~1 nm thick ALD MN (M=Ti, Ta) was found to be adequate to block silicide formation up to ~ 580 °C and ~ 620 °C for TiN and TaN, respectively, and also aided in superior coverage of the CVD ruthenium overlayer (>90%). The results reported here might be useful to ascertain annealing temperature and time for BEOL process and integration optimization without reaching a state where ruthenium silicides start forming.

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Section: Kinetics Of Silicide Formation With and Without A Barriersupporting

confidence: 67%

Atomic layer deposited ultrathin metal nitride barrier layers for ruthenium interconnect applications

Dey

Yu²,

Consiglio³

et al. 2017

Journal of Vacuum Science &Amp; Technology A: Vacuum, Surfaces, and Films

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“…In state-of-the-art wafer technology, a barrier layer of Ta/TaN prevents the diffusion of copper into silicon. [6][7][8] Presently, the copper layer is fabricated via a two-step process. First, a copper seed layer is grown by Physical Vapor Deposition (PVD) and this layer protects the underlying tantalum against oxidation.…”

mentioning

confidence: 99%

Electrodeposition from a Liquid Cationic Cuprous Organic Complex for Seed Layer Deposition

Schaltin¹,

Brooks

Stappers³

et al. 2011

J. Electrochem. Soc.

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Continuous layers of 20 nm of copper have been deposited on a tantalum substrate from the liquid cationic cuprous organic complex [Cu(MeCN) 2 ][Tf 2 N]. This type of ionic liquid, with a high concentration of copper(I) ions permits to achieve high nucleation densities. Furthermore, extremely high overpotentials (up to 5.0 V) can be applied without decomposition of the ionic liquid. The deposition of copper has been investigated by cyclic voltammetry (CV), atomic force microscopy (AFM), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The resulting copper deposits can be useful as seed layers for aqueous copper filling.

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“…The effective activation energy of Cu 3 Si formation for stacks with ALD TaN (E a ∼ 1.5 ± 0.1 eV) and TaAlN (E a ∼ 1.3 ± 0.1 eV) are close to the reported value for grain boundary diffusion of Cu (1.3 eV) (21), whereas the Cu 3 Si effective activation energy for the stack with PVD TaN (E a ∼ 2.3 ± 0.1 eV) is closer to the reported value for lattice diffusion (2.7 ± 0.1 eV). 21 Although the temperature of Cu 3 Si crystallization and corresponding barrier failure . Grazing incidence in-plane X-ray diffraction data for ALD TaAlN (Ta:Al cycle ratio = 8), ALD TaN and PVD TaN, all deposited on a Si(100) single crystal substrate.…”

Section: Resultsmentioning

confidence: 99%

In Situ Ramp Anneal X-ray Diffraction Study of Atomic Layer Deposited Ultrathin TaN and Ta_1-xAl_xN_yFilms for Cu Diffusion Barrier Applications

Consiglio

Dey

et al. 2016

ECS J. Solid State Sci. Technol.

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films with x = 0.21 to 0.88 were deposited by atomic layer deposition (ALD) and evaluated for Cu diffusion barrier effectiveness compared to physical vapor deposition (PVD) grown TaN. Cu diffusion barrier effectiveness was investigated using in-situ ramp anneal synchrotron X-ray diffraction (XRD) on Cu/1.8 nm barrier/Si stacks. A Kissinger-like analysis was used to assess the kinetics of Cu 3 Si formation and determine the effective activation energy (E a ) for Cu silicidation. Compared to the stack with a PVD TaN barrier, the stacks with the ALD films exhibited a higher crystallization temperature (T c ) for Cu silicidation. The E a values of Cu 3 Si formation for stacks with the ALD films were close to the reported value for grain boundary diffusion of Cu whereas the E a of Cu 3 Si formation for the stack with PVD TaN is closer to the reported value for lattice diffusion. For 3 nm films, grazing incidence in-plane XRD showed evidence of nanocrystallites in an amorphous matrix with broad peaks corresponding to high density cubic phase for the ALD grown films and lower density hexagonal phase for the PVD grown film further elucidating the difference in initial failure mechanisms due to differences in barrier crystallinity and associated phase. The continuous scaling of Cu interconnects for sub-10 nm technology nodes calls for development of ultrathin and conformal Cu diffusion barriers. Due to its ability to conformally deposit films with nanoscale thickness control, atomic layer deposition (ALD) is an attractive method for depositing refractory metal nitride diffusion barrier layers, as opposed to a line-of-sight technique such as physical vapor deposition (PVD).1 In this regard, we have previously demonstrated extendability of Cu fill (with Ru seed layer) below 25 nm linewidth (200 nm height) when PVD TaN is replaced with ALD TaN.2 In 40 nm Cu dual damascene structures with 3 nm barrier layers, ALD TaN has also been shown to reduce via resistance by ∼28% compared to PVD TaN in spite of 20x lower blanket resistivity for PVD TaN.3 In order to further improve ALD grown TaN and minimize Cu diffusion through these ultrathin barrier films, it is desirable to avoid forming polycrystalline films with inherent grain boundary diffusion pathways. Accordingly, alloying refractory transition metal nitrides with a third element (as for example Al) may offer a promising method for maintaining metastable amorphous films by interrupting the typical polycrystalline phase formation. 4,5 In this regard, ALD of the ternary compound Ta 1-x Al x N y is of potential interest for Cu barrier applications. Presently there is scarce literature on ALD of this ternary compound which warrants further investigation of film growth and barrier properties. In a recent review of ALD processes for metallization by Li,6 only one publication of ALD of TaAlN-based compounds was reported. In this study by Alén et al.7 Ta-halide precursors were used with trimethylaluminum (TMA) as a reducing agent to deposit Ta(Al)N(C) films and the barrier properties...

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Diffusion barrier property of TaN between Si and Cu

Cited by 239 publications

References 17 publications

Atomic layer deposited ultrathin metal nitride barrier layers for ruthenium interconnect applications

Atomic layer deposited ultrathin metal nitride barrier layers for ruthenium interconnect applications

Electrodeposition from a Liquid Cationic Cuprous Organic Complex for Seed Layer Deposition

In Situ Ramp Anneal X-ray Diffraction Study of Atomic Layer Deposited Ultrathin TaN and Ta_1-xAl_xN_yFilms for Cu Diffusion Barrier Applications

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Diffusion barrier property of TaN between Si and Cu

Cited by 239 publications

References 17 publications

Atomic layer deposited ultrathin metal nitride barrier layers for ruthenium interconnect applications

Atomic layer deposited ultrathin metal nitride barrier layers for ruthenium interconnect applications

Electrodeposition from a Liquid Cationic Cuprous Organic Complex for Seed Layer Deposition

In Situ Ramp Anneal X-ray Diffraction Study of Atomic Layer Deposited Ultrathin TaN and Ta1-xAlxNyFilms for Cu Diffusion Barrier Applications

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In Situ Ramp Anneal X-ray Diffraction Study of Atomic Layer Deposited Ultrathin TaN and Ta_1-xAl_xN_yFilms for Cu Diffusion Barrier Applications