Methods for forming tungsten film using fluorine-free tungsten precursors such as tungsten chlorides are provided. Methods involve depositing a tungsten nucleation layer by exposing a substrate to a reducing agent such as diborane (B2H6) and exposing the substrate to a tungsten chloride, followed by depositing bulk tungsten by exposing the substrate to a tungsten chloride and a reducing agent. Methods also involve diluting the reducing agent and exposing the substrate to a fluorine-free precursor in pulses to deposit a tungsten nucleation layer. Deposited films exhibit good step coverage and plugfill.