A method of forming a structure on a substrate, includes forming a nucleation layer within an opening of the substrate within a processing chamber. The method further includes forming a passivation layer on at least a portion of the nucleation layer by introducing radical treatment into the processing chamber. The method further includes forming a tungsten fill layer within the opening over the passivation layer and the nucleation layer, wherein the tungsten fill layer is formed by a plurality of treatment cycles. Each treatment cycle includes pulsing a first gas at the substrate for a pulse time duration while concurrently flowing a second gas over the substrate, and purging the first gas and the second gas by flowing a purge gas over the substrate for a purge time duration.