Graphene as an atomically thin barrier to Cu diffusion into Si

Juree Hong, Sanggeun Lee, Seulah Lee, Heetak Han, Chandreswar Mahata, Han Wool Yeon, Bonwoong Koo, Seong Il Kim, Taewook Nam, Kisik Byun, Byung Wook Min, Young Woon Kim, Hyungjun Kim, Young Chang Joo, Taeyoon Lee

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Abstract

The evolution of copper-based interconnects requires the realization of an ultrathin diffusion barrier layer between the Cu interconnect and insulating layers. The present work reports the use of atomically thin layer graphene as a diffusion barrier to Cu metallization. The diffusion barrier performance is investigated by varying the grain size and thickness of the graphene layer; single-layer graphene of average grain size 2 ± 1 μm (denoted small-grain SLG), single-layer graphene of average grain size 10 ± 2 μm (denoted large-grain SLG), and multi-layer graphene (MLG) of thickness 5-10 nm. The thermal stability of these barriers is investigated after annealing Cu/small-grain SLG/Si, Cu/large-grain SLG/Si, and Cu/MLG/Si stacks at different temperatures ranging from 500 to 900 °C. X-ray diffraction, transmission electron microscopy, and time-of-flight secondary ion mass spectroscopy analyses confirm that the small-grain SLG barrier is stable after annealing up to 700 °C and that the large-grain SLG and MLG barriers are stable after annealing at 900 °C for 30 min under a mixed Ar and H2 gas atmosphere. The time-dependent dielectric breakdown (TDDB) test is used to evaluate graphene as a Cu diffusion barrier under real device operating conditions, revealing that both large-grain SLG and MLG have excellent barrier performance, while small-grain SLG fails quickly. Notably, the large-grain SLG acts as a better diffusion barrier than the thicker MLG in the TDDB test, indicating that the grain boundary density of a graphene diffusion barrier is more important than its thickness. The near-zero-thickness SLG serves as a promising Cu diffusion barrier for advanced metallization.

Original languageEnglish
Pages (from-to)7503-7511
Number of pages9
JournalNanoscale
Volume6
Issue number13
DOIs
Publication statusPublished - 2014 Jul 7

All Science Journal Classification (ASJC) codes

  • Materials Science(all)

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  • Cite this

    Hong, J., Lee, S., Lee, S., Han, H., Mahata, C., Yeon, H. W., Koo, B., Kim, S. I., Nam, T., Byun, K., Min, B. W., Kim, Y. W., Kim, H., Joo, Y. C., & Lee, T. (2014). Graphene as an atomically thin barrier to Cu diffusion into Si. Nanoscale, 6(13), 7503-7511. https://doi.org/10.1039/c3nr06771h