论文信息 - Investigation of monolayer MX2 as sub-nanometer copper diffusion barriers

Investigation of monolayer MX2 as sub-nanometer copper diffusion barriers

We investigate four monolayer transition metal dichalcogenides (TMDs) — MoS2, WS2, MoSe2, and WSe2 — transferred to silicon substrates as possible sub-nanometer copper diffusion barriers compatible with back-end-of-line temperatures. Based on top-down scanning electron microscope (SEM) and cross-section transmission electron microscope imaging, we demonstrate that the W-based TMDs act as diffusion barriers up to 360°C, while Mo-based TMDs fail at temperatures as low as 300°C. Analysis by SEM indicates that points of failure occur as pinholes, suggesting that mechanical damage may be the origin of failure. Further analysis by X-ray photoemission spectroscopy on as-grown TMDs reveals all four to be chemically unaffected by copper at temperatures as high as 600°C, indicating that directly-grown TMDs still have potential as sub-nanometer diffusion barriers.

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