Relationship between 〈111〉-oriented Cu film and thin Ta–W–N barrier

Abstract

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.