Self-Assembled Nano-Stuffing Structure in CVD and ALD Co(W) Films as a Single-Layered Barrier/Liner for Future Cu-Interconnects

Hideharu Shimizu, Akihito Kumamoto, Kohei Shima, Yoshihiko Kobayashi, Takeshi Momose, Takeshi Nogami, Yukihiro Shimogaki

Research output: Contribution to journalArticlepeer-review

9 Citations (Scopus)

Abstract

Cobalt film with tungsten [Co(W)] has the potential to be an effective single-layered barrier/liner in interconnects, due to its good adhesion with Cu, low resistivity compared with TaN, and comparable barrier properties to TaN. To reduce the resistivity of Co(W), oxygen-free Co(W) was fabricated from oxygen-free precursors, bis(N-tert-butyl-N-ethylpropionamidinato) cobalt and bis(tert-butylimino)bis(dimethylamino) tungsten, by chemical vapor deposition (CVD) and atomic layer deposition (ALD). Our results showed that W addition improved the barrier properties of both CVD-Co(W) and ALD-Co(W) against Cu diffusion. The diffusion coefficient of Cu in Co(W) was reduced by W addition. The activation energy of Cu in CVD-Co(W) and ALD-Co(W) was 1.5 eV and 1.7-1.8 eV, respectively; whereas that in CVD-Co was 1.0 eV. Improvement in the barrier properties of Co(W) was attributed to the amorphous-like structure created by W. High-resolution transmission electron microscopy and multivariate spectral analysis of the nanoscale properties of Co(W) revealed that the improvement in the barrier properties was due to the self-assembled segregation of W atoms at the grain boundary. The segregated W atoms in both CVD-Co(W) and ALD-Co(W) films may act as a stuffing material. These results suggest Co(W), especially ALD-Co(W), as a promising material for Cu-interconnects in future ultra-large-scale integrated circuits.

Original languageEnglish
Pages (from-to)P471-P477
JournalECS Journal of Solid State Science and Technology
Volume2
Issue number11
DOIs
Publication statusPublished - 2013 Nov 18
Externally publishedYes

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials

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