Application of In-Situ Nitrogen Plasma Treated Amorphous-like Tungsten Silicide Film as Barrier Material in the Application of Copper Gate Electrode

Abstract

An amorphous-like tungsten silicide film, deposited by chemical vapor deposition at a higher flow ratio of 2.5 of WF6/SiH4, was used as the barrier layer in the copper gate electrode. This film processes superior barrier characteristics to those of the typical tungsten film at a lower flow ratio of 0.4 of WF6/SiH4 because it lacks the fast diffusion paths of columnar grain boundaries. We proved that the film successfully suppressed copper atom diffusion toward the gate oxide during annealing at 600°C for 30 min. We also found that the amorphous-like tungsten silicide film exhibits better barrier characteristics after in-situ nitrogen plasma treatment at 300°C for 5 min.