Nucleation and growth characteristics of electroplated Cu on plasma enhanced atomic layer deposition-grown RuTaN direct plate barriers

A study has been carried out to understand the mechanism that enables plasma enhanced atomic layer deposition (PEALD)-grown RuTaN barriers to support direct (seedless) copper electroplating. In particular, the effects of changing the liner surface chemistry on the subsequent plated copper nucleation behavior have been evaluated. Amperometric measurements and short pulse plating experiments were carried out directly on PEALD-grown RuTaN barriers. To enhance copper nucleation, a liner surface cleaning protocol was developed and evaluated. In order to understand the effect of intrinsic liner composition and conductivity on the film microstructure and subsequent plated copper nucleation, a study of copper nucleation density as it relates to the Ru:Ta ratio in the liner was carried out. The thickness extendibility of these direct plate liners was also explored. These liners were also tested for potential use in sub-45-nm copper metallization applications.