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We examine a structure/texture of a thin TaWN film applicable to the Cu(111) orientation by using automated crystal orientation mapping in transmission electron microscopy. The 5 nm thick TaWN film with an fcc-TaN structure shows (111) orientation in spite of being extremely thin. This orientation of the TaWN film results in highly-oriented growth of Cu (111), and also contributes to the increase in Cu grain size. Such structural features have useful that effectively prevent an increase in the resistance of the Cu interconnect.

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We examined a thin Ta–W–N film as an underlying material candidate for the Cu(111) orientation. It became clear that a 5-nm-thick Ta–W–N film leads to the high orientation of Cu(111). It was difficult to understand this mechanism, but it was clarified by introducing a measurement system with high resolution. The structure of the Ta–W–N film was based on fcc-TaN with a slightly expanded lattice and showed a (111) orientation, resulting in a lattice match with Cu(111). It is newly confirmed that this result is due to the thin Ta–W–N film having a (111) orientation and favorable lattice matching with Cu(111). Moreover, the Ta–W–N film showed good properties as a diffusion barrier for protecting against Cu diffusion. These results will be useful for future metallization technology.

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