A method of forming a tungsten nucleation layer using a sequential deposition process. The tungsten nucleation layer is formed by reacting pulses of a tungsten-containing precursor and a reducing gas in a process chamber to deposit tungsten on the substrate. Thereafter, reaction by-products generated from the tungsten deposition are removed from the process chamber. After the reaction by-products are removed from the process chamber, a flow of the reducing gas is provided to the process chamber to react with residual tungsten-containing precursor remaining therein. Such a deposition process forms tungsten nucleation layers having good step coverage. The sequential deposition process of reacting pulses of the tungsten-containing precursor and the reducing gas, removing reaction by-products, and than providing a flow of the reducing gas to the process chamber may be repeated until a desired thickness for the tungsten nucleation layer is formed.