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

We examine a thin TaWN fim as a material candidate that satisfies the characteristics of both an underlying material for Cu(111) preferred orientation and thermally-stable barrier against Cu diffusion. It became clear that the 5 nm-thick TaWN film has good barrier properties of sufficiently suppressing the Cu diffusion even after annealing at 700 °C for 1 h. Simultaneously, the Cu film on this TaWN film shows the (111) highly orientation. It was difficult to understand this mechanism, but it was clarified by introducing new measurement system. The structure of this barrier is based on the fcc-TaN with the slightly expand lattice and shows the (111) orientation, resulting in the lattice match with Cu(111). It was found that the TaWN is useful as a material that has two properties of the barrier material and underlying material for Cu(111) orientation. These results will be useful for future metallization technology.