Bottom up deposition of advanced iPVD Cu process integrated with iPVD Ti and CVD Ru

Ishizaka, Tadahiro; Sakuma, Takashi; Kawamata, Masaya; Yokoyama, Osamu; Kato, Takara; Gomi, Atsushi; Yasumuro, C.; Toshima, Hiroyuki; Fukushima, Toshihiko; Mizusawa, Yasushi; Hatano, Tatsuo; Hara, M.

doi:10.1016/j.mee.2011.04.048

Cited by 14 publications

(12 citation statements)

References 1 publication

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“…On one hand, nanoparticles of a specific size are desired for high catalytic activity . On the other hand, Ru interconnects require conformal deposition inside ultrasmall 3D features that often result in void or seam formation, leading to increased resistance and poor electromigration performance . Void formation may be prevented by a bottom‐up fill of the 3D feature, which requires area‐selective deposition of Ru on the bottom of the feature (typically a metal from the lower‐lying conductor) and not on the sidewalls (typically a dielectric).…”

Section: Introductionmentioning

confidence: 99%

Diffusion‐Mediated Growth and Size‐Dependent Nanoparticle Reactivity during Ruthenium Atomic Layer Deposition on Dielectric Substrates

Soethoudt

Grillo

Marques

et al. 2018

Adv Materials Inter

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consisting of two or more alternating self-limiting surface reactions. These selflimiting surface reactions enable thin-film deposition with thickness uniformity over large-area substrates, (sub-) monolayer thickness control, and conformal deposition in 3D structures. [1] During the first ALD cycles the precursors mainly react with the substrate rather than with the ALD-grown material. The surface termination of the substrate can therefore strongly affect the growth behavior during this initial period. [1][2][3] Depending on the nature of the ALD-grown material, the substrate, and the process conditions, ALD can lead to different growth regimes, resulting, for instance, in the deposition of ultrathin continuous films, deposition of highly dispersed nanoparticles, or area-selective deposition. [4] Continuous thin films have a wide variety of applications including nanoelectronics, coatings, and optical components, and their deposition requires either 2D growth or high particle density to achieve fast film closure. Nanoparticles dispersed on a surface are desired for heterogeneous catalysis, and their production requires island-type deposition with a well-defined particle size and particle density. Area-selective deposition can enable nanoscale bottom-up patterning, which allows accurate self-alignment between small features which is difficult to achieve in conventional top-down patterning. [5] To enable area-selective deposition, the growth behavior should be surface-dependent such that the deposition is at the same time favored on designated areas of the substrate and inhibited on others. For each of the aforementioned applications, an understanding of the surface dependence of the initial stages of growth can inform the tailoring of the ALD process to the desired application. [6] ALD of noble metals has received considerable attention because of its potential in applications such as catalysis [7] and nanoelectronic devices. [8] Ruthenium is considered an ideal candidate for novel nanoscale catalysts [9,10] as well as for replacing copper as a conductor in future low-level nano-interconnect structures for integrated circuits. [8] ALD of Ru however presents application-specific challenges. On one hand, nanoparticles of a specific size are desired for high catalytic activity. [10] On Understanding the growth mechanisms during the early stages of atomic layer deposition (ALD) is of interest for several applications including thin film deposition, catalysis, and area-selective deposition. The surface dependence and growth mechanism of (ethylbenzyl)(1-ethyl-1,4-cyclohexadienyl) ruthenium and O 2 ALD at 325 °C on HfO 2 , Al 2 O 3 , OH, and SiOSi terminated SiO 2 , and organosilicate glass (OSG) are investigated. The experimental results show that precursor adsorption is strongly affected by the surface termination of the dielectric, and proceeds most rapidly on OH terminated dielectrics, followed by SiOSi and finally SiCH 3 terminated dielectrics. The initial stages of growth are characterized by the formation a...

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Section: Introductionmentioning

confidence: 99%

Diffusion‐Mediated Growth and Size‐Dependent Nanoparticle Reactivity during Ruthenium Atomic Layer Deposition on Dielectric Substrates

Soethoudt

Grillo

Marques

et al. 2018

Adv Materials Inter

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“…Good wetting of the substrate liner material is necessary to facilitate the Cureflow process and to prevent Cu agglomeration during the surface diffusion process. Based on literature reported values [1], [4]- [8], the spreading parameter S used to gouge the Cu/Ru wettability has a value of greater than 0.75 J/m 2 , and a complete wetting of Cu on Ru is expected…”

Section: Resultsmentioning

confidence: 99%

Characterization of Cu Reflows on Ru

Yang

Flaitz

Edelstein

2011

IEEE Electron Device Lett.

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As compared to conventional Cu reflows on Ta, lower temperature reflow anneals of Cu on Ru are achieved. Cu films are reflowed into 40-nm-wide features at an optimum temperature of 250 • C with a measured activation energy of 0.8 eV. Although higher anneal temperatures can shorten the process time, they also tend to increase hollow metal defects (missing Cu within patterned features). Compared to the control electroplated samples, the reflow-annealed samples do not show bigger Cu grains in the final structure. The observed resistance reduction from the reflowed samples is attributed to higher purity within the Cu interconnects.

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“…The steady-state growth per cycle (GPC) of ALD TaN was ~ 0.7 Å/cycle at 350 °C as described previously 14,15 and the steady-state GPC of ALD TiN was ~0.35 Å/cycle at 430 °C. The deposition of the metal nitride layer was followed by CVD of ~ 3 nm ruthenium using a Ru3(CO)12 precursor 16 . A control stack of CVD Ru (3 nm)/Si was also studied for barrierless metallization.…”

Section: A Film Depositionmentioning

confidence: 99%

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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Bottom up deposition of advanced iPVD Cu process integrated with iPVD Ti and CVD Ru

Cited by 14 publications

References 1 publication

Diffusion‐Mediated Growth and Size‐Dependent Nanoparticle Reactivity during Ruthenium Atomic Layer Deposition on Dielectric Substrates

Diffusion‐Mediated Growth and Size‐Dependent Nanoparticle Reactivity during Ruthenium Atomic Layer Deposition on Dielectric Substrates

Characterization of Cu Reflows on Ru

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

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