Method for depositing uniform tungsten layers by CVD

摘要

Within wafer and wafer-to-wafer uniformity of W layers deposited by CVD, employing N2 for increased reflectivity, is significantly improved by omitting N2 during at least a portion of deposition. Embodiments include depositing a W nucleation layer on a TiN layer employing gaseous WF6 during a nucleation phase, omitting WF6 during an interposition phase during which substantially no W deposition occurs, depositing a W layer employing gaseous WF6 during a main deposition phase, flowing N2 gas at least during the terminal portion of the main deposition phase and omitting N2 gas during at least a portion of the nucleation phase and/or interposition phase, e.g., omitting N2 gas during the entire interdeposition phase.