Patent ID: 7955972

Claim:
A method of forming a tungsten layer in a small width feature, comprising: providing a substrate having a feature with an opening width of no more than about 400 Angstroms forming a conformal tungsten nucleation layer in at least the feature by alternating pulses of a boron-containing reducing agent and a tungsten containing precursor at a substrate temperature of between about 250-350° C., wherein no hydrogen is flowed during or between the pulses; after forming the conformal tungsten nucleation layer, heating the substrate to thereby raise the substrate temperature to at least about 375° C.; and after raising the substrate temperature to at least about 375° C., substantially filling the feature with a tungsten bulk layer by simultaneously exposing the substrate to a tungsten-containing precursor and hydrogen at a substrate temperature of at least about 375° C. to thereby deposit tungsten by a chemical vapor deposition process in at least the feature.