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.

Structural analysis of TaWN ternary alloy film applicable to Cu orientation control

“…In our previous study, we have examined the Cu(111) orientation control on thin barrier and have demonstrated it using TaWN barriers. [8][9][10] This realized Cu(111) orientation without adopting the double-layer structure of a thick underlying material for obtaining Cu(111) orientation and a diffusion barrier material for suppressing Cu diffusion, which have been reported so far. As far as we know, there was no report that the preferential orientation of Cu(111) was obtained on a thin nitride film without using an epitaxial relationship.…”

“…First, we briefly summarize our reports so far. [8][9][10] The composition of the TaWN film was determined Ta 30 W 36 N 34 by AES analysis. 8) The structure of the TaWN film with 100 nm thickness was a state of fcc-TaN phase.…”

Fundamental evaluation of orientation and grain size of Cu film in Cu/TaWN/SiO2/Si system

“…On the other hand, we proposed TaWN alloy films with the above two functions in our previous study, 14) and we demonstrated that the 5 nm thick TaWN alloy film is an excellent barrier in the Cu/ TaWN/Si system, which effectively suppresses Cu diffusion. [14][15][16] Furthermore, we demonstrated that a Cu film with a high orientation of Cu(111) on the TaWN/Si system can be obtained using only a 5 nm thick TaWN alloy film without the need for an underlying material for Cu orientation. 16) In ADMETA2022, we reported formation of the Cu film with Cu(111) orientation on the TaWN/SiO 2 /Si system using X-ray diffraction (XRD) and ω-rocking curve measurements.…”

Diffusion Barrier Characteristics of WSiN Films

“…Takeyama and Noya [33] reported that a W 65 N 35 film in the W 2 N phase exhibited barrier properties up to 800 • C for 1 h annealing. A 5-nm-thick TaWN film with a (111) orientation exhibited barrier properties against Cu diffusion at 500 • C in a vacuum for 1 h [34]. Crystalline CrWN films were applied as a diffusion barrier up to 650 • C in a vacuum for 1 h, as reported in a previous study [35].…”